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Hay just wondering what type of tranny fluids ok to use all we got in house is coastal dexron-III mercon premium?

B&M TrickShift is the best I've found for Ultramatics.

I think you'll find some mixed experiences here. Type F and Type FA are claimed to be the closest to what was originally used in Ultramatics, Type A. My own experience is that I got occasional direct drive "groan" until I switched from Dexron/Mercon III back to Type A and 15,000 miles since have been problem-free. Others who claim to have insight into the fluid composition say that Dexron/Mercon and others except Type F and FA contain slip modifiers which enchance smooth shifts in modern units by allowing clutches to grip gradually, and that this would be contrary to what you'd want in a transmission like Ultramatic with a direct lock-up. Can't say this is true or not, just that Type F solved my problem.

Type F works fine for me. If I were having problems with my first generation Ultramatic, I might try B&M TrickShift but it's kinda pricey by comparison.

As already stated, Dexron has a friction modifier (creates slip) that is of no use to Ultramatic. Type A is straight mineral oil (10w) and is still available. Type F contains detergents plus ZDDP which (according to one patent I was looking at) can corrode copper alloys (great news for the Packard 12) under certain conditions involving heat when not balanced by a neutralizing additive. So if the Borg Warner Simpson transmission does not contain any bronze parts that may be a warning sign.

However, with Type A you need to pay close attention to the maintenance schedule.

I second Eric's recommendation of B&M Trick Shift, especially if you're experiencing any direct drive clutch slippage. The dinosaur juice, not the synthetic. There are two types you know.

No, I didn't know there were 2 types, how do you tell the dinasour juice from the synthetic? Labels different?

I thought type A fluid also had some component of whale oil and when because of restrictions, that became NLA it caused the shift to more modern formulations starting in 60's.

HH56. I'm glad u brought up the whale oil. Whale oil is what i assumed the Green Hornet meant by "Dragon Juice". Whale oil content is exactly what i was advised of during the early 70's. But i think by that time the whale oil had already been eliminated. According to at least 3 Chev Engineers, the whale oil was eleminated due to cost.

I've found that the Dexron II,III or IV or Dexron-Mercon works best in my 56 T'Ultra. The direct drive clutch groan occurs only on very rare occasions, usually when cold but even then rare.

PV8 Thanks for confirming the memory re whale oil. I didn't recall Type A as being only straight mineral oil. There was another product that might have been mineral oil. Believe I read Hudsonite, the fluid used in their cork clutch setup, might have been--but can't recall if that is fact or speculation.