Power steering fluid 2 parts question

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brutherb

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I am completely refilling the power steering fluid resivoir. The recommended fluid is ATF 4+. Does everyone use this or do most use regular power steering fluid. Second part if I think the previous owner used regular fluid will it matter if I fill it with ATF 4+ and there is residual standard power steering fluid left in there, how would I flush the system
 

TexasRammer

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you have to use atf 4+. is the fluid in there clear right now? if its not red then they used power steering fluid which will ruin the system.
 

BigSloth

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99% of off the shelf generic PS fluid, clear or red, will mix with ATF. It wont hurt anything to have some residual PS fluid in there, the ATF4 requirement is mainly because of the seal conditioners to keep everything from leaking. It's got nothing to do with viscosity or anything.

The only PS systems I've ever seen develop a problem from running PS fluid is honda(causes foaming) and BMW/Mercedes(designed for mineral oil).
 

DannyMK2

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99% of off the shelf generic PS fluid, clear or red, will mix with ATF. It wont hurt anything to have some residual PS fluid in there, the ATF4 requirement is mainly because of the seal conditioners to keep everything from leaking. It's got nothing to do with viscosity or anything.

The only PS systems I've ever seen develop a problem from running PS fluid is honda(causes foaming) and BMW/Mercedes(designed for mineral oil).

power steering fluid is never red. if its red, its atf. power steering fluid is a clear/light amber color. honda uses their own specific power steering fluid. if you car/truck calls for atf, use the atf. if it calls for psf, then use psf. dont mix and match them. they are not the same thing. running psf in a system designed for atf can lead to pump failure.

a small bit of residual psf in the system wont hurt it, so you dont have to go crazy flushing it out. just disconnect the lines at the rack and let the system drain out for a while, then refill with the atf and bleed the system. you will probably feel that the steering is smoother with the atf.
 

BigSloth

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the clear PS fluid is, in essence, the same base stock hydraulic oil that ATF is made from. The viscosity of both is so similar it allows them to be interchangeable in hyrdraulic systems outside of a transmission, of course. ATF just takes that same base stock, adds friction modifiers, seal conditioners, red dye, and specialized chemicals to maintain clutch life. The difference between specs(ATF+4, Dex, merc, WS, etc..) is the type, and amounts of these additives. This is how you end up with multispec fluids, where they find that certain additives, or more of them, have no effect on transmissions, so they can dope them up with all the different additives and call it multispec.

With the exception of the seal conditioners, a lack of the other parts will not cause any harm to a hydraulic pump system like a PS pump. Chrysler designs their PS systems to run ATF because its cheaper, and it helps the pumps last longer(though they never seem to). As long as you have mostly ATF4 in the system, the pump will receive the neccessary conditioners and will not have any problems.
 

DannyMK2

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the clear PS fluid is, in essence, the same base stock hydraulic oil that ATF is made from. The viscosity of both is so similar it allows them to be interchangeable in hyrdraulic systems outside of a transmission, of course. ATF just takes that same base stock, adds friction modifiers, seal conditioners, red dye, and specialized chemicals to maintain clutch life. The difference between specs(ATF+4, Dex, merc, WS, etc..) is the type, and amounts of these additives. This is how you end up with multispec fluids, where they find that certain additives, or more of them, have no effect on transmissions, so they can dope them up with all the different additives and call it multispec.

With the exception of the seal conditioners, a lack of the other parts will not cause any harm to a hydraulic pump system like a PS pump. Chrysler designs their PS systems to run ATF because its cheaper, and it helps the pumps last longer(though they never seem to). As long as you have mostly ATF4 in the system, the pump will receive the neccessary conditioners and will not have any problems.

i had bought a car a few years ago that called for dexron atf for the power steering fluid. when i bought the car, i was almost sure it needed a power steering pump since the steering was so tight. when i checked the power steering fluid, it was clear. i drained it, refilled it with atf, bled the system out, and the steering was perfect again. saved myself a good chunk of change by just putting the proper fluid in it and thats first hand experience. the only reason i see for not using the proper fluid is either an emergency or ignorance. theres really no monetary savings to running power steering fluid over atf, so why wouldnt you run the spec'd fluid?

i agree that if you have mostly atf in the system, your fine. but if your fluid looks clear or almost clear, you need to drain the system.
 

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