petawawarace Posted February 8, 2021 Report Share Posted February 8, 2021 (edited) I have a newer GM 5 speed gearbox in my car that has just been gone over. Any recommendations for what oil to use for endurance racing these? Edited February 8, 2021 by petawawarace Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted February 8, 2021 Report Share Posted February 8, 2021 Which gearbox? Quote Link to comment Share on other sites More sharing options...
petawawarace Posted February 8, 2021 Author Report Share Posted February 8, 2021 2 hours ago, wvumtnbkr said: Which gearbox? F23. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted February 8, 2021 Report Share Posted February 8, 2021 Oh, isn't that one of them there fwd dooflatches? No help from me. I can tell you that my WC T5 likes royal purple synchromesh (I hate royal purple, but it was recommended by the guy that wrote the book* on modifying T5 trans). Trans has been pretty great as far as longevity is concerned. The T5 has a couple of carbon fiber bits and also some yellow metal bits. Apparently, these 2 materials require different lubrication properties. Synchromesh was the best at handling both. *Paul Cangialosi is the authors name. He owns / or is part of 5speeds.com. Ymmv. 1 Quote Link to comment Share on other sites More sharing options...
wd6681 Posted February 8, 2021 Report Share Posted February 8, 2021 Anything marketed as an MTF will work well. Typically gl4, viscosities like 70w80 through 80w90 with most being 75w90. Not going to get into the branded thing... Just that it's easy to pay too much Quote Link to comment Share on other sites More sharing options...
mender Posted February 9, 2021 Report Share Posted February 9, 2021 I used Redline MTL in the Fiero transaxle (getrag 282) and likely will be using same in the F23 that's in it now. Quote Link to comment Share on other sites More sharing options...
shanehutton Posted February 9, 2021 Report Share Posted February 9, 2021 We run Motul gear 300 and haven’t blown anything up. Quote Link to comment Share on other sites More sharing options...
wd6681 Posted February 9, 2021 Report Share Posted February 9, 2021 Looks like factory fill was likely atf, so you will need something thin like 70w80 (example shell sprirax gxme), amsoil is another. Or just a dex 3 atf Quote Link to comment Share on other sites More sharing options...
mender Posted February 9, 2021 Report Share Posted February 9, 2021 https://www.cobaltss.net/forums/drivetrain-79/f23-fluid-compatability-164949/ Maybe I won't be using MTL... Quote Link to comment Share on other sites More sharing options...
petawawarace Posted February 9, 2021 Author Report Share Posted February 9, 2021 Yeah I saw it was just a Dex 3 or 6 ATF. We ran it stock for 2 8 hr races without any issues, but I rebuilt it and was curious if anyone found something better is all. Quote Link to comment Share on other sites More sharing options...
petawawarace Posted February 9, 2021 Author Report Share Posted February 9, 2021 (edited) I read an article from Amsoil that their Sycromesh 5W-30 is compatible and better than ATF for manual trans that don’t need the friction modifiers. My Diff is a Torenson style so no clutch packs to worry about. I wouldn’t think ATF is thinner than 5w-30? Edited February 9, 2021 by petawawarace Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted February 9, 2021 Report Share Posted February 9, 2021 Be careful... at and engine oil use different scales (that cross over) for viscosities. 1 Quote Link to comment Share on other sites More sharing options...
wd6681 Posted February 11, 2021 Report Share Posted February 11, 2021 On 2/8/2021 at 9:57 PM, petawawarace said: I read an article from Amsoil that their Sycromesh 5W-30 is compatible and better than ATF for manual trans that don’t need the friction modifiers. My Diff is a Torenson style so no clutch packs to worry about. I wouldn’t think ATF is thinner than 5w-30? Older atfs are around the viscosity of 20w motor oil and newer atfs are thinner. For thin gearbox applications I have had luck with shell sprirax gxme 1 Quote Link to comment Share on other sites More sharing options...
67Mustang Posted February 11, 2021 Report Share Posted February 11, 2021 (edited) On 2/8/2021 at 4:08 PM, wvumtnbkr said: *Paul Cangialosi is the authors name. He owns / or is part of 5speeds.com. Ymmv. Paul is the guy that built and or rebuilt most of the Corvette 4+3's back in the 80's when they were running in SCCA. He made those things live even with the OD. I talked to him about our C4. Good book, good guy. Edited February 11, 2021 by 67Mustang 3 Quote Link to comment Share on other sites More sharing options...
MMiskoe Posted February 11, 2021 Report Share Posted February 11, 2021 Synthetic ATF in all my miata transmissions. Eventually third gear gets crunchy, but "eventually" is measured in seasons, plural. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted February 12, 2021 Report Share Posted February 12, 2021 1 hour ago, MMiskoe said: Synthetic ATF in all my miata transmissions. Eventually third gear gets crunchy, but "eventually" is measured in seasons, plural. That's what happens to the rx7 trans too (mostly same trans). Idemitsu solved that issue. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.