4 quarts will do the trick, with just a little bit left over.
Pennzoil Synchomesh
Pro
Joined: Dec 2009
Posts: 606
Likes: 1
From: Waco Texas
Honestly I am underwater in this cess pool! I have done my own personal tests for about a year between GM Syncromesh, Penzzoil SM and the latest one previously posted that GM recommends now. I am about 4 months into the new " manual gearbox and transfer case fluid" and I cannot say I am impressed. I think I may go back to the Pennzoil SM myself as I have generated the same notchiness after oil gets hot as my original reason for oil replacement. It never felt right since the change, but I also changed the clutch out as well and was putting the notchiness on the clutch/pressure plate disengagement. Mine is a 99' as well so some trannys may like one oil, while the older Borg Warners may want the Pennzoil Synchromesh? Regardless I am going back and see how the Pennzoil does this time. If it is instantly better again, then this is what our tranny prefers. As far as overall protection, who knows?
Thread Starter
Instructor
Joined: Aug 2010
Posts: 154
Likes: 2
From: Genesee Co Michigan
I have the Penzoil S/M in mine and it does shift a little harder when cold but is fine once it's warmed up. I store mine in the winter so it's not an issue for me. I talked to the Tremec factory rep an he said that's what he recommends. Works very well for "friskier" driving.
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Honestly I am underwater in this cess pool! I have done my own personal tests for about a year between GM Syncromesh, Penzzoil SM and the latest one previously posted that GM recommends now. I am about 4 months into the new " manual gearbox and transfer case fluid" and I cannot say I am impressed. I think I may go back to the Pennzoil SM myself as I have generated the same notchiness after oil gets hot as my original reason for oil replacement. It never felt right since the change, but I also changed the clutch out as well and was putting the notchiness on the clutch/pressure plate disengagement. Mine is a 99' as well so some trannys may like one oil, while the older Borg Warners may want the Pennzoil Synchromesh? Regardless I am going back and see how the Pennzoil does this time. If it is instantly better again, then this is what our tranny prefers. As far as overall protection, who knows?
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
Since I bought my car new I've tried a few different fluids. I've got an '03 Z06 which has a Hurst shifter and I've also done the Anti-venom mod. I've used Mobil 1 synthetic, Red-line ATF and presently have Royal Purple Synchromax fluid in my car. Shifting is not what I'd call terrible but I've always felt it could be better. The RP has given me the best results so far but the first couple of shifts in the morning, especially 1-2 are a little stiff/notchy until it warms up. I've always wondered if there wasn't some magical fluid that could smooth it out. Keeping up with this post I was ready to try the Pennzoil, but now I'm not so sure. I'm reading that some love it and others find it too thick and not an improvement. According to what some have gotten from Tremec, is the Pennzoil the correct fluid for an '03 MN12 trans? Just want to know before I lie on the garage floor and make a mess.
Instructor
Joined: Jun 2010
Posts: 220
Likes: 0
o well im gonna ask anyway! does our tranny our rear diff use syn oil? the dexron 3 is NOT SYNthetic correct? im just trying to find what you guys have the best luck with and not have issues down the road..the issue i have with mixing syn and non syn is that GM says the tranny never needs changed or serviced and that always bothers me since it usually means they have some special syn lifetime fluid they use like (Audi) but then when people(myself included) changed to say redline we noticed a major smooth and amazing new shifting feel that made you go wow that really worked. so i dont mind how the car shifts now i love the beefier trannys and shifts as they feel more built proof and strong unlike a lot of slush boxes out there (sry c6 and new camaro owners
)
so bottom line is whats in the zo6 c5 tranny and rear Diff as far as syn or non syn oil
seems you guys are fans of either amsoil or that syncromesh by pensoil
)so bottom line is whats in the zo6 c5 tranny and rear Diff as far as syn or non syn oil
seems you guys are fans of either amsoil or that syncromesh by pensoil
Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
Here's the update from my earlier post on the GM DEX III replacement.
About 3 years ago, I tried the GM Syncromesh #12345349 in my 2000.
Way too stiff; hard to shift when cold, and still pretty syrupy when hot.
Just felt too thick everywhere.
Drained that and found old-style Pennzoil DEX III. Big difference, felt just like it did with the factory lube.
After a couple years, though, I began to notice it seemed a little stiff when it got hot. Great feel when cold, but just a tad sticky when hot.
I also have noticed a very slight whine in 5th geat at low speeds. Had it awhile, probably before the switch to Pennzoil, just not sure when it started. Very slight, could have been there for years.
When I saw the post above about the GM DEX III replacement #88861800, I decided to try it. It looked, smelled, poured just like DEX III. After a few weeks in the tranny, it shifts just like DEX III also.
The slight hot "stickiness" I felt with the Pennzoil DEX III is gone, this stuff feels the same whether cold or hot. No issues at all; not silky smooth, but then it's never been; it's a Vette. The very slight 5th gear whine is still there, but I didn't really expect to change that when basically going from DEX III to DEX III equivalent.
Conclusion: the 88861800 is the GM recommended lube for the C5.
It replaces thier previous DEX III, and very very likely is the exact same DEX III with another number - to avoid the trademark issues.
Whether it's better than some of the aftermarket products, can't say.
But I can say it works much better in my tranny than GM Syncromesh, and a little better hot than 2-year-old Pennzoil DEX III.
DG
About 3 years ago, I tried the GM Syncromesh #12345349 in my 2000.
Way too stiff; hard to shift when cold, and still pretty syrupy when hot.
Just felt too thick everywhere.
Drained that and found old-style Pennzoil DEX III. Big difference, felt just like it did with the factory lube.
After a couple years, though, I began to notice it seemed a little stiff when it got hot. Great feel when cold, but just a tad sticky when hot.
I also have noticed a very slight whine in 5th geat at low speeds. Had it awhile, probably before the switch to Pennzoil, just not sure when it started. Very slight, could have been there for years.
When I saw the post above about the GM DEX III replacement #88861800, I decided to try it. It looked, smelled, poured just like DEX III. After a few weeks in the tranny, it shifts just like DEX III also.
The slight hot "stickiness" I felt with the Pennzoil DEX III is gone, this stuff feels the same whether cold or hot. No issues at all; not silky smooth, but then it's never been; it's a Vette. The very slight 5th gear whine is still there, but I didn't really expect to change that when basically going from DEX III to DEX III equivalent.
Conclusion: the 88861800 is the GM recommended lube for the C5.
It replaces thier previous DEX III, and very very likely is the exact same DEX III with another number - to avoid the trademark issues.
Whether it's better than some of the aftermarket products, can't say.
But I can say it works much better in my tranny than GM Syncromesh, and a little better hot than 2-year-old Pennzoil DEX III.
DG
I appreciate the update Wrench. I just ordered 4 quarts of the GM 1800 fluid. Im:o to say it hasnt been changed in 3 years. So im pretty sure ill feel a difference.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Instructor
Joined: Feb 2010
Posts: 159
Likes: 9
From: Greenville NC
I just changed the fluid in my 2000 with synchromesh (tranny) and mobile one (differential), Both are working great and made a huge improvement.
the differential was making a little bit of a whine at 75 or so under constant throttle, and to my disappointment I found some small metal filings in the fluid, and it was dark colored and seemed fairly thin - I'm assuming I'm looking at a rebuild or replace at some point in the near future. RPM transmission did the differential strut and clutch, not sure who put the 4.10 gear set in it or what else was / wasn't done. I'm just driving it for now with only a slight whine at 75 or so.
The transmission is shifting GREAT.
It doesn't hurt that I followed some adivce on here and have been swapping the clutch fluid out daily until it's almost clean all the time. You guys ROCK!!! Thanks
oh, and yes, this is the car that got smashed a few months ago - it looks better than it ever has and everything seems to be in order... Life is good.
the differential was making a little bit of a whine at 75 or so under constant throttle, and to my disappointment I found some small metal filings in the fluid, and it was dark colored and seemed fairly thin - I'm assuming I'm looking at a rebuild or replace at some point in the near future. RPM transmission did the differential strut and clutch, not sure who put the 4.10 gear set in it or what else was / wasn't done. I'm just driving it for now with only a slight whine at 75 or so.
The transmission is shifting GREAT.
It doesn't hurt that I followed some adivce on here and have been swapping the clutch fluid out daily until it's almost clean all the time. You guys ROCK!!! Thanks
oh, and yes, this is the car that got smashed a few months ago - it looks better than it ever has and everything seems to be in order... Life is good.
Race Director
Joined: Aug 1999
Posts: 15,299
Likes: 33
From: Houston Texas
Since I bought my car new I've tried a few different fluids. I've got an '03 Z06 which has a Hurst shifter and I've also done the Anti-venom mod. I've used Mobil 1 synthetic, Red-line ATF and presently have Royal Purple Synchromax fluid in my car. Shifting is not what I'd call terrible but I've always felt it could be better. The RP has given me the best results so far but the first couple of shifts in the morning, especially 1-2 are a little stiff/notchy until it warms up. I've always wondered if there wasn't some magical fluid that could smooth it out. Keeping up with this post I was ready to try the Pennzoil, but now I'm not so sure. I'm reading that some love it and others find it too thick and not an improvement. According to what some have gotten from Tremec, is the Pennzoil the correct fluid for an '03 MN12 trans? Just want to know before I lie on the garage floor and make a mess.
This is exactly the situation I'm in. I have the RP Synchromax that I put in several years ago. First couple of shifts are stiffer than when the tranny starts to get a little hot but not impossible. Was all set to try the Pennzoil, and now have read this thread and am not sure what I will put in.
Doesn't seem to be a one and all consensus.
Rick
Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
FINALLY i made it back from the desert and got to change my tranny fluid. I will say that my fluid was not red anymore, but more of a brown:o. I used the GM 88861800 and so far the car is shifting GREAT. Before everyonce in a while get hung. Even with the B&M i have. Tranny feels smooth as butter
. I havent had the chance to do any highspeed runs but its cold where i am and it shifts the same cold or warm. Im sure when the weather changes over to more than mild, ill be able to really see how well this fluid does from completely cold to hot. Stick to the GM fluid.
. I havent had the chance to do any highspeed runs but its cold where i am and it shifts the same cold or warm. Im sure when the weather changes over to more than mild, ill be able to really see how well this fluid does from completely cold to hot. Stick to the GM fluid.
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Since I bought my car new I've tried a few different fluids. I've got an '03 Z06 which has a Hurst shifter and I've also done the Anti-venom mod. I've used Mobil 1 synthetic, Red-line ATF and presently have Royal Purple Synchromax fluid in my car. Shifting is not what I'd call terrible but I've always felt it could be better. The RP has given me the best results so far but the first couple of shifts in the morning, especially 1-2 are a little stiff/notchy until it warms up. I've always wondered if there wasn't some magical fluid that could smooth it out. Keeping up with this post I was ready to try the Pennzoil, but now I'm not so sure. I'm reading that some love it and others find it too thick and not an improvement. According to what some have gotten from Tremec, is the Pennzoil the correct fluid for an '03 MN12 trans? Just want to know before I lie on the garage floor and make a mess.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
As I previously mentione, I've done the anti-venom mod. I've got many thousands of miles since doing it and while it does provide some benefit in shifting, there has been no negatives from doing it. So if you've got any interest in trying it, you don't have to worry about any adverse situations.
I also have magnetic drain plugs in both my trans and the diff. I'm not positive where I got them because it was quite awhile ago, but try Eckler's. I'm pretty sure that where they are from.
I also have magnetic drain plugs in both my trans and the diff. I'm not positive where I got them because it was quite awhile ago, but try Eckler's. I'm pretty sure that where they are from.
Team Owner
Joined: May 2001
Posts: 87,357
Likes: 1,592
From: Western NY
Intermediate
Joined: May 2010
Posts: 45
Likes: 0
From: Cincinnati Oh
I have not tried Pennzoil Synchromesh in my 2003 Z06 yet, as I just picked it up this past weekend, but have been running it in my daily driver. I have a 93 Cherokee 5-speed that was getting extremely notchy on shifting, expecially when stopped after a period of driving and shifting back into first. I would have to give it a good push sometimes to get it into gear.
I decided to change the trans fluid to see if that would be a cheap fix. After changing to the Pennzoil Syncromesh it is literally a night and day difference. It seemed to take a few weeks to totally smooth out, but now it shifts extremely smooth and zero notchy shifts now!
I decided to change the trans fluid to see if that would be a cheap fix. After changing to the Pennzoil Syncromesh it is literally a night and day difference. It seemed to take a few weeks to totally smooth out, but now it shifts extremely smooth and zero notchy shifts now!
Drifting
Joined: Sep 2007
Posts: 1,649
Likes: 50
From: Goldsboro NC
Have had the New GM transfer and tranny fluid in my car for 2+ months. Im wondering if i maybe put a little too much in the tranny. I dont have a whine nor does it feel funny.....unless its a high rpm shift. Seems 4k rpm+ wants to get a little notchy but no whine of any kind. I dont know if its bc of the change or maybe the simple fact that there may be too much fluid. Driving around town it shifts great. Any thoughts?
Tech Contributor
Joined: Jan 2007
Posts: 19,450
Likes: 1,155
From: Dyer, IN
Have had the New GM transfer and tranny fluid in my car for 2+ months. Im wondering if i maybe put a little too much in the tranny. I dont have a whine nor does it feel funny.....unless its a high rpm shift. Seems 4k rpm+ wants to get a little notchy but no whine of any kind. I dont know if its bc of the change or maybe the simple fact that there may be too much fluid. Driving around town it shifts great. Any thoughts?
