A-727 swap to 360 what trans fluid recommendation.

72polarbear

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finally ready to put fluid in my freshly installed 727 rebuilt nearly stock so just wondering what you guys would recommend and what’s the procedure to start up. Thanks
 
finally ready to put fluid in my freshly installed 727 rebuilt nearly stock so just wondering what you guys would recommend and what’s the procedure to start up. Thanks
Dexron 3 was factory recommended in 1972. I have used Dexron 3 with good performance in a 1968 727 that I rebuilt. It's behind a 1969 440.
You will pay more for ATF+4, although it's fine for your car.
 
Viscosity loss (20 hour KRL Shear test) Dexron-3 40%, ATF+4 10%. Dexron-3 = garbage.
-In other words, you are saying that Chrysler recommended customers put garbage in Chrysler transmissions?
-If that's the case, how did our cars survive in the 1960s and 1970s under high stress Police use? NASCAR? NHRA?
-ATF+2 did not become available until 1980, how did our cars survive until then?

Where are you getting these statistics? Link to article or actual test report?



By contrast, here's an email from Richard Ehrenberg, Tech Editor for Mopar Action Magazine. I wrote regarding trans oil for a 1990 pickup.
Note: lockup trans were not in production until 1979 and do not apply to 1972 Polara.

Date: 2/8/2010 10:29:41 PM Eastern Standard Time

From: tech@richardehrenberg.com (Rick Ehrenberg)
To: my email

"The only issue with Dexron is possible lockup shudder. Other than that, Type
F is really the way to go. Personally, I'd try the el Cheapo gallon jug
Wal-Mart juice. No possible harm, just the shudder - a 25% chance of that.
And there's a good chance that your '90 518 isn't even lockup.

ATF+4 is really good stuff - synthetic. Wal-Mart does have that, too."
 
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Non-lockup torque convertors are heat pumps and they heat and shear the transmission fluid quite a bit, way more than the lockup converters that came in the 80's. ATF has long been formulated exclusively for transmissions with lockup converters.

Thing is, the performance degredation in ATF is not noticable. Your car will still move after 20, 30, 40 k miles, but I bet the change in the stall speed and input/output RPM difference is measurable vs when the oil was new.

What's interesting is that I look at my '67 factory service manual, at the maintenance and lubrication section, where they show what to do at X months or X miles, and it only goes out to 3 years / 36k miles. Change engine oil every 3 months or 4k miles. Transmission fluid? Nothing. Just keep it topped up, but no scheduled changes out to 3 years or 36k miles. Maybe because at some point you had a transmission problem and in your city there was a transmission shop on every block, and any service required dumping the fluid anyways?
 
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