There was a long go around on this , on this site, about a year or so ago..won’t rehash. It involves filter pore size and viscosity of fluid when cold too. Might look up. Bottom line for me after a lot of wavering around , was mopar atf (?5 or 6) or equivalent , was the best stuff, why 100k miles, with no trans fluid change now. 100% synthetic. So it flows well at low temp, seemed to be the main upgrade . Tried to find out the why of the F vs Dexron vs mopar atf 5 etc. . What IS different about linings? Are they different ? Inconclusive at best. Linings now vs then? Vague terms like shift quality get into it. I also heard stories that brass parts in some transmissions do not like some additives.
Newer trans filters with finer pores supposedly need the less viscous TF. With older fluids, and newer 727 filters, flow may even get choked when cold. Or worse. I did not even know filter porosity had changed.. All this from an SAE publication I happened to read.
It seems the trend is to filter the fluid more aggressively , finer filters, based on 60 years of automatics, which makes sense to me, for long life, and to be sure it pumps very well at all temps. Thick fluid cold start stresses pumps and seals, pressure goes up.? . So a return line filter (external ,like 62 300) and the best atf (mopar 4, 5 or 6?) also might make sense. It is also like 18 $ a quart. Has to be a good reason mopar decided to use that as factory fill?? .
All of this is just 10 W oil , regular , or more expensive , synthetic-- (like Mobil 1) with various additives; hard to believe that auto trans design truly varies in any TRULY significant way , --but maybe they do. All have steels , seals , and friction liners. And all those materials are not the same now, as in 57. I had NOS cast iron kits, the seals were junk in the bag.
Reminds me how transmissions , manual, all had to have special high $ “gear oil” in 60’s ; now they fill with engine oil. (Corvette started that, I think) . Gears are still same gears in there. Bearings too. Seals are formulated to resist swelling, viton is best. Early transmissions had various things. Seals look a lot different now. Old rubber thick ones get hard. I also find it hard to believe all these small private label oils can do any real oil refining..right? No way. Relabeling something else. Mobil discovered and researched synthetic out of airplane turbine use, that is the real stuff.. Airplane synthetic turbine oil as a base stock is probably ok in an auto trans.. more than ok.
No strong opinions, just random info…. Your mileage may vary. And an interesting thing --to find out more about it.
Any bad experiences out there? That matters…
If I don't hear any adverse comments, I may just go ahead and be the first "guinea pig"!
Las Cruces, NM
1957 300C convertible (almost ready to roll, again!)
A few years ago there was a pretty lengthy thread on our forum about which ATFs were both suitable and available for our Torqueflites. The original ATF in the cast iron Torqueflite was Type A, but that is no longer being made and offered on the market. It has been conclusively agreed that Type F works very well as a substitute for Type A, and furthermore that most other ATFs, like Dexron and Mercon, will induce disappointing (and sometimes strange) performance characteristics.
ATF is the fluid with the very most critical specifications of any in your car. Getting it wrong can mess up the transmission functions, and even wear it out prematurely. So yes, Go with only Type F in your Torqueflite.
And your question about synthetic vs. petroleum base? You're probably not going to stress your ATF by racing or pulling a trailer anymore, but it is true that synthetic is superior to petroleum-based in many performance characteristics, and inferior in none. So you'll probably be fine using standard Type F, and you'd be finer yet using Redline or Royal Purple synthetic Type F.
I have no trouble finding type F at WalMart
Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
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