What is the best fluid to run in the drive trim pumps? Mine are oildyne pumps.

Thanks
502ss

30w motor oil or Merc PS and PTT fluid

30W motor oil.....really?

I guess I am glad I asked because I was going to put hydraulic fluid in it, You would think, it's a hydraulic pump and hydraulic pistons, it would run on hydraulic fluid!

Thanks
502ss

I would use ATF. Like you said, hydraulic pump, should use some sort of hydraulic oil. ATF is a hydraulic oil. The motor oil would probably work just fine, but I would use ATF.

clpbs was right! I dug through all the paperwork that came with the boat and found the specifications for the pumps, They call for 10w30 motor oil. I would have never guessed!

If yu want want them to move faster use type f fluid or psf.

if you dont know whats in there just replace all the fluid with the merc trim fluid, different people add different kinds of fluid over the years and some of it wont mix well, and cause problems

Merc says not to use ATF in these pump. There is something about that fluid it doesnt like. I own a perfomance boat shop on Clear Lake and thats all we use is 30w.

The pumps and cylinders have been completely drained and cleaned. I am in the process of making all new stainless lines so there won't be any mixing of fluids for me!

talked to Parker/ oildyne wed. (one of the engineers) he said trans fluid was fine and I told him I used amsoil and he was already aware of there trany fluid and was ok with it and said he never heard of any problems related to it's use also called factory merc. tech and they said the same