Question about ATF in Integral trim system

Greetings,

I have a 1987 Black Max 150 HP with the Integral trim system. The manual calls for Type A or Type AF ATF. The possible problem is that I put Castrol Type F in it instead before realizing my possible mistake? It has worked though, just don't want to mess up any O-rings or seals if the Type F should not be in there?

Is the Type F ATF suitable (I'm not sure of the differences?) as it's already in the system? If not, is Type AF the same thing as Dexron II/III?

If I need to change it, what's the best way to get the old stuff out?

Thanks for help!

Re: Question about ATF in Integral trim system

Its oil. ATF differs from engine oil in its use of friction modifiers and wetting agents ( surfactants ) . Those friction modifiers are calibrated to the types of wet clutches used in the transmission. The wetting agents help the ATF act as a coolant and help scrub the transmission clean. Type F, AF, A and Dexron etc can indeed be used in other makes of transmissions but it will alter the shift characteristics as slippage or the lack of it will result. Ive built transmissions for racing and used straight mobil one 0 weight motor oil as a fluid. Shifts fast and withstands heat well. None of this has anything to do with how the fluid will work in a trim pump. In short the trim pump doesnt really care what you put in it. ATF isnt going to dissolve or attack butyl rubber seals no matter what type you use. Woe unto you if you ever put brake fluid in the system though. Ive used 2 cycle motor oil in them before in a pinch.

Re: Question about ATF in Integral trim system

wired247 said:

Its oil. ATF differs from engine oil in its use of friction modifiers and wetting agents ( surfactants ) . Those friction modifiers are calibrated to the types of wet clutches used in the transmission. The wetting agents help the ATF act as a coolant and help scrub the transmission clean. Type F, AF, A and Dexron etc can indeed be used in other makes of transmissions but it will alter the shift characteristics as slippage or the lack of it will result. Ive built transmissions for racing and used straight mobil one 0 weight motor oil as a fluid. Shifts fast and withstands heat well. None of this has anything to do with how the fluid will work in a trim pump. In short the trim pump doesnt really care what you put in it. ATF isnt going to dissolve or attack butyl rubber seals no matter what type you use. Woe unto you if you ever put brake fluid in the system though. Ive used 2 cycle motor oil in them before in a pinch.

Click to expand...

Thanks for the explanation!

Re: Question about ATF in Integral trim system

wired247 said:

Its oil. ATF differs from engine oil in its use of friction modifiers and wetting agents ( surfactants ) . Those friction modifiers are calibrated to the types of wet clutches used in the transmission. The wetting agents help the ATF act as a coolant and help scrub the transmission clean. Type F, AF, A and Dexron etc can indeed be used in other makes of transmissions but it will alter the shift characteristics as slippage or the lack of it will result. Ive built transmissions for racing and used straight mobil one 0 weight motor oil as a fluid. Shifts fast and withstands heat well. None of this has anything to do with how the fluid will work in a trim pump. In short the trim pump doesnt really care what you put in it. ATF isnt going to dissolve or attack butyl rubber seals no matter what type you use. Woe unto you if you ever put brake fluid in the system though. Ive used 2 cycle motor oil in them before in a pinch.

Click to expand...

I have seen atf impregnate the rubber on very high pressure trim systems (systems with a single trim cylinder pushing against 100HP and larger). It causes the rubber to crystalize and become brittle. The bigger engines with two trim rams should not have this problem since two trim rams double the number of square inches and the location of the trim piston increases the fulcrum. Both act to create more lifting power at lower pressures.