PS Fluid or ATF??

[Mike Geary]

What's the proper fluid to fill my newly-rebuilt 1965 power steering system with?

MAG

[Gerry Proctor]

Re: PS Fluid or ATF??

Power steering fluid. Automatic transmission fluids can cause seal failure.

[Wayne W.]

Re: PS Fluid or ATF??

I have run transmission fluid in every car that I have for as long as I can remember and have had no problems at all. I know that there may be some additives in transmission fluid that may not be in PS fluid, but they are essentially the same product. I have always thought that it was just another ploy to get you to pay a bundle for a pint of transmission fluid. GM evens recomends transmission fluid when the other isnt available. Think about that. Would they do this if there was a real problem?

[Mike Geary]

Re: PS Fluid or ATF??

I should have mentioned that the original cap specifies Type A ATF, whatever that means in today's range of chemistries.

[Duke W.]

"Whale sperm"

Type A ATF was the original automatic transmission fluid that goes back to the late

forties. Because automatic transmissions have wet clutches they requires a "friction

modifier" to prevent chatter - just like positraction units.

The original friction modifier in ATF (and the positraction additive) was a small quantity of

whale oil. Beginning about 1970, whale products were outlawed in the US, so other

friction modifiers had to be developed and this lead to other ATF specifications.

That small bottle of friction additive we buy for our positraction axles is sometimes

affectionately referred to as "whale sperm", both because it was once a whale product,

and because of the unit price per ounce.

Duke