Power Steering Fluid

[Mayhem_J30]

Now that you guys have molded me into an anal retentive maintenance freak about my car I checked and replaced some of my PS fluid. I just sucked the resivoir empty and refilled with new. Will do again in a couple days unless someone knows of an easier way.Anyway, the fluid I pulled out wasn't even close to red nor did it even have a red tint, it was just plain brown. Sorry Dennis, I know I just ruined your day. :oface But what damage could have been done because of old bad fluid? I rarely here about PS pumps dying so should I worry about it?

[Q45tech]

The pump almost never fail unless you have a Lexus then they always fail.The brown is heat oxidation of the ATF AND particles of the rubber seals in the rack and the inside of hoses.Rack leaks are the number one concern as it cost more to replace than a pump.Just like CV axles dirt is the killer on the precision steering shafts [replace boots] and replace ATF so the breakdown products don't attack the rack seals from the inside.

Fluid shear -- squezzzzzzzzzzing the ATF thru a high pressure pump is 3-5 times worse in a PS system than a transmission due to higher pressures.

[Mayhem_J30]

also, why is it recommended to use ATF over PS fluid? If it's so much better why do manufacturers just label ATF as both PSF and ATF?

[Q45tech]

Annual fluid exchanges are just about doing things on a schedule and doing what you can to defer the expense of parts replacement.

If an engine needs oil/filter replacement every 90 days to deliver 300,000 miles of service [if that quality was designed in], then annual changes should deliver the max possible on the other systems. Eventually you run into material/metal fatigue/stress and heat issues which fluid changes can't protect against but they are way out in the future!

[911/Q45]

Near the front of the oil pan is a big banjo bolt on the high pressure line between the power steering pump and the steering rack. If you disconnect that you can drain the pump itself and the reservoir, about 75% of the total fluid I think. Do that twice and the system should be pretty clean.

[Q45tech]

The color of ATF is red [dye] by convention and PS doesn't need to pass the slick/slip test of clutch lockup as ATF does so PS can be produced less expensively.But the SAE specs of the base product [without ATF dyes and additives] are equal.

If heat wasn't a problem with PS why would all cars have PS coolers......look around you'll find extra convoluted metal tubing in the circuit sometimes an actual finned cooler!

On a Nissan we use the ATF for both as it is a stock [inventory issue] and the 20 cents per quart lower cost is not significant vs keeping two types........it costs us about $275 more per year to use ATF vs a dedicated clear PS fluid not accounting for floor space, pumps for 55 gallon drums, and ordering costs.

[OLU40]

Wow, I would have never guessed you could use ATF fluid. Geez!:eek: You learn something everyday. Do Infiniti dealers do this or is it something underground to most?

[Q45tech]

It is so underground that it is printed in CAPITAL LETTERS in the owners manual and of course the shop manual....." "Recommended fluid is Automatic Transmission Fluid DEXRON Type"