Transmission fluid - manual
Thread Starter
Burning Brakes
Joined: Jul 2012
Posts: 944
Likes: 31
From: WV
Transmission fluid - manual
Approx 5 years ago, I had a well known Mid Atlantic driveline specialist rebuid and upgrade the 6speed manual transmission in my 1999 Corvette. It is an HPDE track car, with about 390 rwhp.
Since then, and following their recommendation, I have used only AC Delco 88861800 fluid in it.
my understanding is that the synchros are sensitive to other fluids, and the above is necessary for that reason.
In a recent order for the above, a National racing parts retailer substituted and sent AC Delco 19540137
Is the substituted fluid an acceptable alternative, or should I remain with 88861800?
Since then, and following their recommendation, I have used only AC Delco 88861800 fluid in it.
my understanding is that the synchros are sensitive to other fluids, and the above is necessary for that reason.
In a recent order for the above, a National racing parts retailer substituted and sent AC Delco 19540137
Is the substituted fluid an acceptable alternative, or should I remain with 88861800?
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,120
From: Dyer, IN
Approx 5 years ago, I had a well known Mid Atlantic driveline specialist rebuid and upgrade the 6speed manual transmission in my 1999 Corvette. It is an HPDE track car, with about 390 rwhp.
Since then, and following their recommendation, I have used only AC Delco 88861800 fluid in it.
my understanding is that the synchros are sensitive to other fluids, and the above is necessary for that reason.
In a recent order for the above, a National racing parts retailer substituted and sent AC Delco 19540137
Is the substituted fluid an acceptable alternative, or should I remain with 88861800?
Since then, and following their recommendation, I have used only AC Delco 88861800 fluid in it.
my understanding is that the synchros are sensitive to other fluids, and the above is necessary for that reason.
In a recent order for the above, a National racing parts retailer substituted and sent AC Delco 19540137
Is the substituted fluid an acceptable alternative, or should I remain with 88861800?
Thread Starter
Burning Brakes
Joined: Jul 2012
Posts: 944
Likes: 31
From: WV
it is a disappointing decision from a previously reliable supplier. And done without any explanation.
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,120
From: Dyer, IN
I would tell them to send you a return label for that fluid. They should have asked you first. Customer service is a rare commodity these days.
Le Mans Master
Joined: Feb 2021
Posts: 6,429
Likes: 4,257
From: Florida
2025 Corvette of the Year Finalist - Unmodified
2024 C5 of the Year Winner- Unmodified
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Maybe check in with the builder and pick his brain…maybe a particular specification he looks for. Perhaps he can also suggest an aftermarket fluid/brand. There are great manufacturers out there like Amsoil, RedLine, and many other choices. Good luck 👍
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Melting Slicks
Joined: Sep 2021
Posts: 2,555
Likes: 1,213
From: Temple Texas
It's my understanding it was the cellulose blocking rings that some claimed deteriorated because of synthetic ATF. Sometime during the C5 run the blocking rings were changed to carbon fiber.
Thread Starter
Burning Brakes
Joined: Jul 2012
Posts: 944
Likes: 31
From: WV
Absolutely amazing, and now beyond frustrating:
After returning the undesired substitute, I changed vendors and ordered the originally desired fluid from Amazon.
What did I receive? MORE of the undesired substitute!!!!!
I will return this flawed shipment as well. But it really has me wondering if GM has declared it an equal.
Geez…..
After returning the undesired substitute, I changed vendors and ordered the originally desired fluid from Amazon.
What did I receive? MORE of the undesired substitute!!!!!
I will return this flawed shipment as well. But it really has me wondering if GM has declared it an equal.
Geez…..
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,120
From: Dyer, IN
Absolutely amazing, and now beyond frustrating:
After returning the undesired substitute, I changed vendors and ordered the originally desired fluid from Amazon.
What did I receive? MORE of the undesired substitute!!!!!
I will return this flawed shipment as well. But it really has me wondering if GM has declared it an equal.
Geez…..
After returning the undesired substitute, I changed vendors and ordered the originally desired fluid from Amazon.
What did I receive? MORE of the undesired substitute!!!!!
I will return this flawed shipment as well. But it really has me wondering if GM has declared it an equal.
Geez…..
https://www.rockauto.com/en/moreinfo...13630&jsn=1259
Thread Starter
Burning Brakes
Joined: Jul 2012
Posts: 944
Likes: 31
From: WV
I just ordered the p/n you want 3 months ago direct from Rock Auto. Don't order auto parts from Amazon....
https://www.rockauto.com/en/moreinfo...13630&jsn=1259
https://www.rockauto.com/en/moreinfo...13630&jsn=1259
mike v
Joined: Feb 2013
Posts: 465
Likes: 92
From: Riner Va
found this info on trany fluids when I upgraded my clutch from c5 coupe to a c5 Zo6. ,, and every thing else back seeing how it
was all out and needed cleaning iside and out.
txdrivetrain.com/fluid-type-transmission-tremec-t56-tr6060-faq/
was all out and needed cleaning iside and out.
txdrivetrain.com/fluid-type-transmission-tremec-t56-tr6060-faq/
Melting Slicks
Joined: Sep 2021
Posts: 2,555
Likes: 1,213
From: Temple Texas
Instructor
Joined: Nov 2015
Posts: 246
Likes: 105
From: Detroit area, Michigan
https://www.txdrivetrain.com/fluid-t...56-tr6060-faq/
Cut and pasted from the link above:
Which type of fluid should I put in my Tremec T56/TR6060 transmission?
Non-synthetic ATF (automatic transmission fluid) only. It will say one or more of these things on the bottle and could be in small print on the back side.- Dexron/Mercon (Dex/Merc) equivalent
- Universal ATF
- Dex 3 ATF
Not Recommended:
- MTF (manual transmission fluid)
- Synchromesh
- Gear oil
- Synthetic ATF
- Semi-synthetic ATF
- Dex 4 or higher
- Mixes of the above fluids
Why not use synthetic fluid? Isn’t it better?
We’ve concluded that synthetic ATF has additives which allow the synchro rings to slip a small amount, causing excessive wear. These additives are made to benefit an automatic transmission which has fluid under high pressure, unlike a manual transmission which isn’t pressurized. We’ve found that the life of the synchro rings is drastically shortened when using synthetic fluid.I’ve used synthetic fluid in my transmission, and it feels fine. Do I need to change it back to non-synthetic fluid?
Theoretically, one could put nearly any type of oil in a Tremec transmission, and it will probably seem fine. While any oil will work to an extent, the issue is longevity of the synchro ring friction material. It will not last long with anything besides non-synthetic ATF.
Burning Brakes
Joined: Feb 2022
Posts: 883
Likes: 971
From: NW Burbs of Chi-Town
2025 C5 of the Year Finalist - Modified
I posted this in another thread...
I have a 98' with the "Paper blocker rings" I did hours and hours of research. In the end I went with the current GM/AC Delco Manual gearbox flavor. PN 88861800. Its a mineral based fluid. The Summit search engine does not list the C5 specifically, but does list this for all Tremec trans used in Corvettes C6 and C7 including the ZR1. In the comments section a couple C5 owners reported in using this fluid as well.
https://www.summitracing.com/parts/ADO-10-4033
GM Tech link on the subject:
https://web.archive.org/web/20140617...hlink/2009/05/
"TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid."
Another tip:
"All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation."
YMMV
Edit: Out of stock at Summit. Scoggin Dickey has it in stock:
https://sdparts.com/i-19932885-genui...I3mUDAAJSH95MM
I have a 98' with the "Paper blocker rings" I did hours and hours of research. In the end I went with the current GM/AC Delco Manual gearbox flavor. PN 88861800. Its a mineral based fluid. The Summit search engine does not list the C5 specifically, but does list this for all Tremec trans used in Corvettes C6 and C7 including the ZR1. In the comments section a couple C5 owners reported in using this fluid as well.
https://www.summitracing.com/parts/ADO-10-4033
GM Tech link on the subject:
https://web.archive.org/web/20140617...hlink/2009/05/
"TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid."
Another tip:
"All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation."
YMMV
Edit: Out of stock at Summit. Scoggin Dickey has it in stock:
https://sdparts.com/i-19932885-genui...I3mUDAAJSH95MM
Last edited by Prop Joe; Dec 17, 2024 at 07:23 AM.
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
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St. Jude Donor '09-'10-'11
Im surprised people are still rebuilding the old transmissions with the crummy blocker rings... Its the perfect opportunity to put something better in while you have it apart, and use a much WIDER variety of fluids.