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I have a 1957 Rocket 88 and was wondering the best auto trans fluid to use? When I google it , it just gives me a bajillion results for motor oil and I am not going to trust the ads. I just want to know if there’s a specific brand that caters to these vehicles?
Thanks!
Beautiful Oldsmobile. I deleted your double thread.
I'm not sure what the early automatics call for. I put the Sam's Club brand ATF in my 71 98 that calls for Dexon/Mercon III. I also use it in the C6 in my 86 Ford truck. No bad effects yet.
Beautiful Oldsmobile. I deleted your double thread.
I'm not sure what the early automatics call for. I put the Sam's Club brand ATF in my 71 98 that calls for Dexon/Mercon III. I also use it in the C6 in my 86 Ford truck. No bad effects yet.
Beautiful Oldsmobile. I deleted your double thread.
I'm not sure what the early automatics call for. I put the Sam's Club brand ATF in my 71 98 that calls for Dexon/Mercon III. I also use it in the C6 in my 86 Ford truck. No bad effects yet.
thank you so much!
sorry I keep double posting. Not sure why it’s doing that 🤷♂️
DO NOT USE any Dexron marked IV, V or VI, or whatever Roman numeral it's up to now.
If the OP's Oldsmobile calls for Type A ATF he should probably look for that. Alot of ATFs (Sam's Club brand included) are universal and will work with Dexon/Mercon III, IV, V, etc.
FWIW, I bought Motorcraft LV ATF from the dealer for the 6F50 in my 2011 Flex when I did transmission service. The transmission still needed a computer flash to shift properly after replacing the fluid. I should have just had it serviced by the dealer.
That being said, I'd treat that early automatic with as much care as a modern transmission.
If he can find A/A he can use it, but it's not gonna be whale oil based like the original. Generally accepted wisdom is Dexron III/Mercon is suitable for older GM transmissions, but IV, V or VI are not. This is one case where the latest formulations are not better than what was available 65 years ago- for this particular transmission anyway.
OP, Dexron III/Mercon is still readily available. Type A Suffix A is not. I know what I'd use. I'd stay away from those "universal" fluids too. Rebuilding a Jetaway HydraMatic is not inexpensive.
Last edited by rocketraider; March 6th, 2023 at 07:09 AM.
Generally accepted wisdom is Dexron III/Mercon is suitable for older GM transmissions, but IV, V or VI are not.
The reason that Dexron IV, V, VI are not suitable for older GM transmissions is that they are synthetic.
Synthetic oils can tend to dissolve the glue used to bind the friction materials to the clutch plates.
Modern fluids labeled as "Type A " are generally petroleum based fluids that are so cheap that they don't meet standards for Dexron III/ Mercon.
I would be leery about using them.
Modern fluids labeled as "Type A " are generally petroleum based fluids that are so cheap that they don't meet standards for Dexron III/ Mercon. I would be leery about using them.
If the entire transmission is being rebuilt, the OP can put whatever type of ATF in it that he wants. Is there any reason to believe that the fiber clutch plates available from Fatsco (the only supplier I know of) are specifically engineered for Type A vs. Dexon/Mercon III? From my understanding, back in the day newly rebuilt automatic transmissions would get Type F ATF (poor man's slick shift). I agree with what was said above though if it's just a filter change or topping off of the transmission.
Off the top of my head I can think of three reputable old car transmission parts suppliers in addition to Fatsco. David Edwards, Northwest Transmission and Classic Transmission.
Type F first appeared in 1967. Before then Ford used Type A Suffix A. Starting around 1959 they were dabbling with and developing Types B, C, and D trying to make Cruise-O-Matics shift well instead of burning out their clutches with slippage. The F formula just happened to work well in performance transmissions, giving a little firmer and crisper shifts, which is also a benefit to the transmission itself.
If current new production clutch packs are made to be compatible with synthetic fluids there's probably no harm or issue using synthetic in a COMPLETELY cleaned and rebuilt transmission. If there's any question about the materials, or if the transmission is simply being topped off or getting a fluid and filter service, best to stick with the fluid formulations the 1957 transmission was designed to use. In this case Dexron III is the successor to the original formulation.
Unless, of course, the GM tech bulletins, Service Guilds and other factory publications are wrong.
March 4th, 2023, 02:43 PM
