C3 - Dexron II vs Dexron III

[Steve B.]

Just drained the automatic transmission fluid in my 76 coupe, replaced filter and gasket as per usual. Fluid replacement specs call for 20 pts. of Dexron II ATF. Question: are there any issues using Dexron III instead? Also, the speedometer cable was leaking at the transmission. When removed the o-ring appeared to be o.k.??? Will any comparable o-ring replacement work or are they specific to this type of application? Any advice would be greatly appreciated.

Thanks,

Steve

[Duke W.]

Re: C3 - Dexron II vs Dexron III

To the best of my knowledge, Dexron III is "backward compatible" with Dexron II and some, but not all, manufacturer's labels will so state.

Even though the O-ring is in one piece it is probaby hardened and compressed after 27 years, so I would strongly suggest a new one. Don't have a part number, but any Chevrolet dealer can look up the number and order it if they don't have it in stock.

Duke

[Greg A.]

Re: C3 - Dexron II vs Dexron III

Duke's correct that Dexron III is backward compatible in all applications requiring Dexron II or IID fluids. I have a nice technical bulletin that explains all of the ATF fluid requirements (Chrysler, Ford, GM, etc.) and will send it to anyone who requests it via e-mail.

Greg

[Clem Z.]

Re: C3 - Dexron II vs Dexron III

when we drag raced with GM trans we used ford fluid because the GM stuff has more built in slip for smoother shifts.