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Rear differential, transfer case, CVT filter/fluid changes, P0868, P1778, CVTz50, step motor, CVT metal shavings

24K views 119 replies 10 participants last post by  Cryogenix1 
#1 · (Edited)
In combing through the threads here, it seems strange that MO owners are overwhelmingly using the drain/fill plugs to change the tranny fluid, despite Nissan's manual providing what I believe to be a simplier option, where you don't have to jack up the car or crawl way underneath it. It appears to be a very straightforward way of doing it that seems less messy and much quicker. In one post, one member wanted to do it, but didn't know which side was the return line. Always amazes me how Nissan chooses to leave out basic yet crucial info like that in most of their service manuals.
 
#69 · (Edited)
Over the past two days, I've been getting a lot of over-taching when accelerating from a stop (even after driving for hours), and MO ended up throwing P1778 twice while simply moving forward on a level surface. It's the first P1778 I've gotten in a think about two weeks. Monitoring the CVTz50 data, I noticed that the SEC pressure readings started to align better, while the PRI pressure readings were far apart and reducing below 1.00 a lot. I also noticed that the STM Step reading that usually has the numbers mirroring each other (e.g. 196/196) were sometimes mismatched (e.g. 185/186).. Since MO was no longer making progress and I'd gone about 4,000 miles since infusing the MMO, it was a perfect time for something new, so I replaced the fluid and filter. It's was snowing after completing the work, so I haven't gone on a test drive yet...

To help purge the fluid, I started the engine once, then used the CVTz50 app to disable all six cylinders so the engine would turn over but not start. I cranked the engine over about six different times after each time seeing the fluid stop coming out.
 

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#70 · (Edited)
Mixed performance. Still had over-taching the first day, but after warmed up things were fine and some aspects had improved, such as a cold start up a hill without letting the car warm up. Day 2, I thought the CVT was done, since things had changed in a bad way. Later on, the P0868 that's been persistent in triggering immediately after beling cleared, and that has been popping up on the TCM since using the CVTz50 app, finally cleared and stayed off, even after driving very aggressively on the highway.

I drained some fluid from the pan to see how things looked (refer to end of video). While I didn't see any shavings, I did notice a lot of murkiness. It might be that aspect of the fluid that's causing such inconsistent performance. In a couple of weeks I plan to drop the pan again and check the magnets and filter to see how things look, provided MO is still running. I realize with the amount of large shavings found in the pan, the CVT's days appear numbered. So, though I might indicate I'm going to replace a step motor if such and such is resolved, I've since decided it's not worth it.

I also believe I misread some of the CVTz50 info. If you look at the attachment "step4 pressure," there's a result from an automatic pressure test performed on the system whenever in D and stopped. It's that data that I believe refers to what I was saying about pressure of .7 being target, .5 a warning and .3 a failure. So, if I'm understanding things correctly, my pressure test at that time averaged .53, which is basically at mimimun and at the warning level. Yesterday, the highest result from that pressure test was .58.
 

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#71 · (Edited)
Today, things started okay, went to better, then ended worse... Pressure test early on was averaging .58. Later, it went as high as .63. (.70 is target, .50 warning, .30 failure). After sitting for two hours and restarting, the STM Step reading "196/196" kept flashing yellow, despite a cold start drive immediately up a steep hill where MO drove perfectly. It wasn't until I came to a stop for about 20 seconds that the pressure test was performed and showed a warning level of .48 as min. and .51 as avg. It remained at .48 for the next 1.5 hours of driving back from the mountains. Had some minor over-taching when accelerating from a stop, but MO drove fine and felt fine.

Checked the CVT fluid level several times during the day, and it was fine. So now I have a few thoughts for tomorrow... Overfill the CVT by a quart and see what happens. Add a quart of MMO to see if the thickness will increase pressure to normalize things. Get some NS-2 to see if it has the ability to cure the low pressure issue. I'm back to getting the P0868 persistently. Acceleration and speed are fine...just the minor over-taching and flashing 196/196 while taking off.
 

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#72 ·
Added a quart of CVT fluid last night. Morning pressure was .063/.063 then tapered off to hold around .56/.58. After getting gas, I noticed the PRI reading dropped to .20 for a split second at idle, then floated around .35 until I got on the gas. Later in the morning, there was a large gap between minimum and average readings, and I knew something was wrong at .50/.58. Later, pressure readings were .48/.57. Ended the day with .50/.53 and with P1778 always popping up instantly while driving back from the auto parts store with CVT cooler filter and CVT pan filter/gasket in hand. I've also been noticing the past few days that the battery charging sometimes drops to 12.94 briefly while cruising, and usually hovers around 13.30 and maxxes out at 13.67. Since the battery is more than three years old and I'm always using electronics equipment and draining it, I might grab a new one tomorrow to make sure my CVT issues aren't due to a failing battery.
 

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#73 ·
I would think you'd be seeing a higher charging voltage if the battery was marginal... The alternator regulator would need to put out a higher voltage to charge the battery...
 
#75 · (Edited)
Auto-electrical has never been my strong suit, so maybe I'm not understanding what the CVTz50 app is telling me. I have two readings...the first seems in realtime and is always fluctuating (e.g. 13.18, 12.94, 13.41). The second reading typically never changes and usually reads 14.40v. I thought the second reading was telling me what the alternating was putting out, and the first what "realtime temporary storage" my battery was able to achieve while being fed from the alternator. I thought that "RTS" was supposed to always remain above 13.60 in order to effectively supply power. Since it wasn't holding that minimum voltage, I thought the battery cells may be losing their ability to retain that short-term storage, thus my considering a new battery. In driving around today with the new serp belt, my cruising voltage has typically remained above 13.41, and more or less floated between 13.41 and 13.85. In prior days, it was floating primarly in the range of 12.90 to 13.33 and sometimes hitting 13.41.

Coincidentally, for the first time in a few days, my pressure readings have improved instead of degraded. The only time those pressure numbers dropped today was immediatlely following an undercarriage rinse, and I noticed the RTS reading had dropped to 12.86. About an hour later, the pressure numbers actually improved from where they started off in the morning, and I noticed the RTS reading was floating above 13.41 Could still be a ground wire issue or crud on the alternator wiring or whatever. Not sure if it's just coincidence that pressure improved a tad after messing around with the charging system. I'll probably pull the alternator wires and clean up all the contact areas and recheck that new ground wire to the chasis.

EDIT: So I really should have read the app details more thoroughly, instead of just skimming them and skipping over some. Looks like the "battery" info is this: "Battery – TCM power supply voltage and voltage on OBD2 socket, V" I guess it's not displaying what I thought it was.
 

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#74 · (Edited)
Since the charging readings in the app have been very erratic lately with wild swings (particularly below 12.90), I took a few minutes to grab the serp belt out of the spare tire area and I installed it tonight. The old belt was nearly six years old, but had no cracks, tension was good, it wasn't glassed over or making any noise, but it had a ton of miles on it and I thought it might somehow be slipping and causing the inconsistent charging. I'll find out tomorrow morning if the new belt did anything to solve that issue. It could also be because I pressure-washed the alternator about a week ago to get off all the dark grime and residue from a coolant leak.
 
#76 ·
Anytime you're reading battery voltage from a control module it's always going to be what that control module is getting, not the voltage at the battery terminals. If you want to approximate the battery terminal voltage then you can hook up your multimeter to the battery terminals and observe the average difference between the battery voltage at the terminals and the scan tool voltage (e.g. scan tool reading is on average 0.3 volts less than the actual voltage at the battery terminals). Once you have that adjustment factor then you can drive around and have a reasonable idea of what actual alternator output is from your scan tool while you're driving.
 
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#77 · (Edited)
Thanks, coffee. I kind of lost sight of that fact that I'm using an app created primarily for transmission functions. I'd definitely get a more accurate voltage reading taking it directly from the source.

All in all, the pressure numbers varied little today and MO drove fine. Min. reading never dipped below .55, and max avg. was .63. I'll wait another day to get some readings before doing anything else. Trying to do one thing at a time and then put some miles on to see if there's any change.

I've been monitoring some dark, oily fluid in the coolant reservoir the past few days, and I'm trying to determine if it's a blown head gasket or a problem with the radiator and tranny cooling lines that are creating the problem. Engine oil looks perfect and tranny fluid looks perfect, and all fluid levels look normal. At the moment, I'm leaning towards it being tranny fluid leaking within the radiator and rising to the top and getting pushed into the reservoir . Maybe that Autozone-bought radiator is junk.

EDIT: I think a quick way to elminate the transmission fluid as the source would be to disconnect the tranny cooling lines and unite them with a barbed union to bypass the radiator for a few days. But then it hit me that the CVT cooler has coolant running to it, and there could be contamination happening there. Might also have to disconnect those coolant lines and join them with a union to bypass the cooler. UPDATE: It smells like motor oil, so it's more than likely a blown head gasket.

QUESTION: Could that old internal CVT leak that I stopped by plugging up the weephole be the source of my current line pressure problem? Say fluid used to make it past the seal (or maybe even an internal housing crack), and over the years that standing fluid in the weephole chamber sealed the leak. Is it possible that pressure can be lost through that area despite no fluid coming out, which could affect line pressure? Or is that just not mechanically viable? Does line pressure not create or impact any internal housing ("gearbox") pressure?
 

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#79 ·
QUESTION: Could that old internal CVT leak that I stopped by plugging up the weephole be the source of my current line pressure problem? Say fluid used to make it past the seal (or maybe even an internal housing crack), and over the years that standing fluid in the weephole chamber sealed the leak. Is it possible that pressure can be lost through that area despite no fluid coming out, which could affect line pressure? Or is that just not mechanically viable? Does line pressure not create or impact any internal housing ("gearbox") pressure?
What weep hole are you referring to? Those are only used to allow for the visible presence of oil (or some other fluid) in case an external seal is leaking. On the CVT, the only weep hole that comes to mind is the one near where the CVT and transfer case mate to let you know if the transfer case and/or CVT output shaft seal are leaking.
 
#78 ·
#80 ·
I'm not sure if you've played with them, I noticed CVTz50 has built in charting function, and also data logging that can be exported to an excel spreadsheet.
I did do some logging, but my version of Excel is from Office 2000 and won't properly open the app's data file, even with the upgrade converters. I could probably open it in Google Docs, if Google still offers that feature.
 
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#82 · (Edited)
Since draining two quarts of tranny fluid and adding a quart of MMO about five days ago, MO hasn't thrown P1778, line pressure has improved slightly and has remained above a min. of .56 (and usually stays at .59 most of the day), and P0868 stays off for about the first two hours of driving, then comes on when I'm stopped and then accelerate slowly - it used to remain on most of the time, and would typically not stay gone even after immediately clearing the code.

In a few days, I plan to drop the pan, check the magnets, remove the step motor and blow it down to make sure metal shavings aren't present and then lube the piston and ensure it moves in and out easily. I'm also planning to use a vibrating device on the underside of the valve body while blowing air and cleaning fluid into those slots, to try to flush out any jammed pieces of metal that may be affecting that pressure solenoid. It may do more harm than good, so I'll have to think more about the benefits vs consequences before doing anything. It would be easier and more thorough to simply remove the valve body and fool around with it on a bench, but I'm not that motivated to play with it. I'll then refill with CVT fluid again and see how things go.

MO really seems to be driving better and has tremendous acceleration and pep that was lacking earlier last year. Since I've recently replaced the plugs and coils, cleaned up the wiring, cleaned the throttle body, and started adding a gallon of lacquer thinner every fourth fillup, those could be the reasons for the performance increase. That possible CVT whine is gone, the loud growl is gone, and the chirp is nearly gone. FYI, the noises vanished prior to replacing the serp belt.

I haven't bothered to get into what oily subtance is making its way into the coolant reservoir. It smells like burnt motor oil. MO still has power and no leaks, and fluid levels appear normal for everything and there's no detectable contamination of the motor oil or CVT fluid, so I'm probably not going to spend any time trying to troubleshoot it. I haven't gotten around to replacing the thermostat. I might not do it.
 

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#83 ·
Since draining two quarts of tranny fluid and adding a quart of MMO about five days ago, MO hasn't thrown P1778, line pressure has improved slightly and has remained above a min. of .56, and P0868 stays off for about the first two hours of driving, then comes up, usually when I'm stopped and then accelerate slowly - it used to remain on all the time, even immediately after clearing the code.

In a few days, I plan to drop the pan, check the magnets, remove the step motor and blow it down to make sure metal shaving aren't present and then lube the piston and ensure it moves in and out easily. I'm also planning to use a virbrating device on the underside of the valve body while blowing air and cleaning fluid into those slots, to try to flush out any jammed pieces of metal that may be affecting that pressure solenoid. It may do more harm than good, so I'll have to think more about the benefits vs consequences before doing anything. I'll then refill with CVT fluid again and see how things go.

MO really seems to be driving better and has tremendous acceleration and pep that was lacking earlier last year. Since I've recently replaced the plugs and coils, cleaned up the wiring, cleaned the throttle body, and started adding a gallon of lacquer thinner every fourth fillup, those could be the reasons for the performance increase. That possible CVT whine is gone, the loud growl is gone, and the chirp is nearly gone. FYI, the noises vanished prior to replacing the serp belt.

I still haven't bothered to really get into what oily subtance is making its way into the coolant reservoir. It smells like burnt motor oil. MO still has power and no leaks, and fluid levels appear normal for everything and there's no detectable contamination of the motor oil or CVT fluid, so I'm probably not going to spend any time trying to troubleshoot it. I haven't gotten around to replacing the thermostat yet. I might not do it.
You would probably enjoy watching Video's by a guy called project farm on youtube. He did a head to head test of motor oils but has done a few with MMO.
 
#84 · (Edited)
Of course, after posting that things were great, MO went ahead and had the lowest line pressure ever this morning at .48/.49, and the P0868 code wouldn't clear from the first drive attempt. Pressure dropped late-morning, then recovered after MO sat idle for a couple. hours, maintaining .54/.56 the rest of the day. Here's a brief video explaining how I'm using the CVTz50 app to get past the cold start drive.
 
#85 · (Edited)
Planned to do probe into the CVT this afternoon, and decided to first change the oil in the transfer case and then do the CVT. Thiings didn't go entirely as planned. From what I can tell, changing the TC gear oil should take about 30 minutes, and you only need a wrench or ratchet wrench for the fill plug, and a hex-socket with 8" long 1/2" drive extension and breaker bar for the drain plug. My only problem was, I didn't have the correct hex-socket. The drain plug is on there very tight, and getting leverage on a too-short allen wrench was impossible, and not something I wanted to slip with and gash open my hand on all the sharp metal in that area.

Also, since it was time for an oil change I decided to throw in a quart of Lucas' "Engine Oil Stop Leaks" just for the hell of it, to see if it can solve the oil in the coolant reservoir.

UPDATE: It's been about six days and the oil is still in the overflow tank. If the radiator is the source of the leak, I wouldn't expect that Lucas product to do anything. Likewise if it were a head gasket issue. I might just head to Autozone with my original receipt and tell them the radiator failed. They'll have me buy a new one, then return the old one for a refund. I've returned defective parts to them before. They're pretty easy to deal with.
 

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#86 · (Edited)
And the Dumb and Dumber act of the day goes to...

After draining two quarts of CVT fluid a few days ago and replacing it with two quarts of Marvel Mystery Oil, my pressure readings have been getting better, and today I saw the best pressure ever at .65/.66. I hit 298,000 miles and MO's running great. So, I decided to revisit the transfer case, something that really wasn't necessary given the conditon of the rear differential oil. But, I was curious...

The drain plug spun out very easily with a 10mm hex-socket and 1/2" drive ratchet with 10" extension. During the reinstallation process, I was talking for the video about certain aspects of MO, and wasn't paying attention to what I was doing while tightening the drain plug. When I finally looked at the plug, I had spun it in too far and cracked the casing. Besides my lack of focus and prevailing stupidity, the other major factor was that I didn't switch to my 3/8" drive ratchet and extension for reinstallation, both of which were lying right beside me for that exact purpose. Instead, I had grabbed and used the 1/2" drive which was way too much leverage for installing a plug in cast metal, especially if not paying attention.

For the first time in my mechanical life, I actually did major damage to something I was trying to fix. As I mentioned in another post, the one thing I hate about recording work is that it can make me lose focus by feeling compelled to entertain the viewer. I'm kind of laughing in disbelief that I've come this far with MO only to sabotage the ending by doing something highly stupid and preventable.

I removed the drain plug, cleaned up the cracks, and loaded up the plug with RTV sealant and smeared it into and around the cracked housing and will let it cure the night before refilling the TC. If this doesn't work, I'll drain it again, clean it up and press some liquid weld into it and let that cure. I might even gunk up the plug with liquid weld to try to seal everything, making draining it that way impossible. But, I only need to make it another 1950 miles...
 

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#88 ·
Good luck. That crack say's "replacement transfer case".

That crack goes way past the where the plug stops.

Aren't you supposed to use some kind of sealer before reusing the plug?

Have a good day.
 
#89 ·
I would think J-B Weld should handle that with ease. It's not under stress, and there's little to no pressure. Even the RTV should work I would think, so long as the surface was totally free of oils before application. I used the aluminum version of J-B Weld to seal some holes in the aluminum deck of my John Deere mower, it was very strong, I was impressed. I also used silicone to seal the magnesium crankcase of my Elsinore 250 with success when I was a teen...
 
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#90 · (Edited)
1) I'm not perfect and of course I've had things happen, such as exhaust bolts snapping off, electrical clip retainers sometimes breaking off, etc. Mostly small stuff, and most happening when I was younger. This is what I consider "real" damage that was 100% avoidable.

2) I used RTV sealant when installing the drain plug.

3) I had JB Weld on hand, but I thought RTV would work fine, provided I used enough cleaner to get everything out. After cleaning everything, I reinserted the clean plug to open up both sides of the crack, then a pressed RTV sealant into boths sides, then removed the plug and let the cracks close up and squeeze the sealant inward and outward. Then I loaded up the plug with sealant and spun it in a few turns, making sure not to go too far that the cracks would open up too much. I'm hoping for a "mushrooming" effect to bond the interior cracks' sealant to the plug sealant, which will, in turn, hold the exterior sealant in place.
 
#92 ·
I recall working on the V6 in my (then) 1999 Blazer and having the poly intake manifold for the throttle body off. It was rather light material and sealed with an O-ring and some fairly small bolts.

When re-installing it, I set the poly manifold in place, looked at the bolts and was just ready to start torquing the bolts down. At the last minute I felt the need to double-check, and I realized that the torque spec was INCH-pounds, not FOOT-pounds. I almost tried to tighten the bolts 12x too tight, which would have broken them off, and probably also broken the manifold.

It's really easy to make such a mistake.
 
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#93 ·
I was a mechanic for around 10 years long long time ago..Van came in for a oil change and front end alignment..I drained the oil and realized the whool front end was shot and spent the next 4 or 5 hours rebuilding and aligning it. Boss went to drive it and realized I never put oil back in it!! I said my screw up I will pay for a new engine..Boss said no just change the oil again and it will be fine..I felt horrible..
After that I started putting the oil filter in the drivers seat so I woudln't make that mistake twice!!

I still remember that 30 years later!! And the reason I rarely let anybody touch my cars :) I wold have paid to have it replaced or did it myself
 
#94 ·
Worst case, if patching compounds and sealants don't work, I'd consider pulling off that broken piece of housing, inserting a tube from the bottom drain plug area (but higher up) to come out the fill plug hole, then carefully use fire-rated expanding foam to seal up the entire cavity. I'm thinking of a few ideas. Not glad this happened, but I enjoy thinking about different fixes. Maybe shove a small, rubber bladder in the hole and inflate it Maybe pack the hole with Silly Putty that's been dunked in Super Glue. I could just drill a small hole beside the shifter, and have a small tube running down to the transfer case's fill hole that I can use to slowly drip-feed gear oil to the transfer case while driving. :)
 
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#96 · (Edited)
So far, so good. Put on about 175 miles and was periodically checking the plug whenever I'd stop somewhere, and everything's fine. The nice thing is, if you drop to one knee and look past the front spoiler you can easily see the drain plug with a flashlight. As an extra precaution, I got some Permetex Steel Weld that I'm going to spread a few light layers of over the entire plug area to ensure the RTV sealant can't be affected by road salt or whatnot, and to really encase and trap the compromised metal to prevent a leak from forming. So, the plug will still be usable.

The only JB Weld I had on hand last night was the waterweld stuff, which probably would've worked. However, I felt given the situation, the RTV was better at adhering to itself and not pulling apart and creating micro-tears in itself as I inserted the drain plug and possibly made the cracks open a hair. I felt with heat and vibrations, RTV was a better option.

The good news that I realized while refilling the TC is, the drain plug (input shaft seal) housing is replaceable by removing a handful of bolts and pulling out out the pass-side CV axle. While not the easiest of jobs, it's better than having to replace the entire TC. I imagine there are lots of bad transfer cases just lying around junkyards that a person could cannibalize if they weren't comfortable with patching a cracked drain plug housing. Looks like the Nissan engineers put a little thought into this. Better thought would have been to create a different design that's less delicate. Maybe just have a tiny ball valve in place of the plug that you simply open to drain the fluid. Attached is a shot of the old fluid coming out and it in the catch container. There were no metal shavings and the oil didn't even appear as though it was mixed with CVT fluid. I'm perplexed. I actually bought some small containers that I was going to use to test how certain fluids I'm using interact with one another. I wonder if the CVT fluid just floats on the gear oil. Also, in looking at the "diagram" attachment, why is it showing three plugs? What is that third plug (5091A) at the bottom for?
 

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#98 · (Edited)
The vibrations I was mostly thinking about were those coming from that CV axle that's going through the drain plug housing ring. I'm not really all that concerned about the vibration, but naturally when making a repair it's always a good practice to consider all factors beforehand. I chose pliable over rigid as the main filler and sub-layer, then over-coated it with a rigid compound for good measure.

In case some of you are wondering about the Marvel Mystery Oil in the CVT, my reasons for using it aren't a mystery.

- My hope was that since MMO is a little thicker/denser, it may help seal/fill any nano-cracks in any component that may be affected by age or by abrasion due to the over-abundance of metal shavings passing through the system.

- Since there's sludge everywhere, the additives in the MMO might help break it down and flush it away, effectively cleaning some of the affected surfaces and perhaps making them operate more smoothly.

- MMO might be able to lubricate certain troubled parts in a different/better way than the CVT fluid can, which might help those troubled components work a little better.

- Since it's possible there are metal shavings stuck within a solenoid, or a seal ring, or on a piston or arm or whatever, maybe the denser MMO has a better chance of grabbing onto those metal shavings and drawing them out (or pushing them away) moreso than the thinner CVT fluid.

- As MMO appears slightly denser than CVT fluid, perhaps it can somehow retard the flow of fluid through the valves (or certain components) just a smidgeon to perhaps create a temporary blockage to aid in increasing line pressure which might create a sudden fluid surge (that wouldn't usually happen) that might create turbulence upon certain parts to aid in forcing a response or again, purging metal shavings or sludge from troubled components.

In the end, perhaps none of what I'm thinking is what's happening, or can happen. The facts are that after using MMO, code P1778 never returns until I do a drain and only add CVT fluid. I know line pressure seemed to increase a few days after draining CVT fluid and adding a heavier dose of MMO. Coincidence? Perhaps. I recently did some Googling and found a Nissan owner (I think with an Altima) who cured his troubled CVT by only using MMO.

AND TO BE CLEAR... I'm not suggesting that anyone use MMO in their CVT if it's working fine. I'm on the last leg of my journey with my MO, and I don't mind trying out a few things on a CVT that has a couple of hiccups.

FYI, I ended up canceling my Liqui Moly order a long time ago, since I felt that cleaning things too thoroughly might create more problems.
 
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