Fluids - Time vs. Mileage

I live in Phoenix (nice dry climate). I purchased a 2000 Infinity with low miles from a nice lady who only drove it to church on Sundays. It has 15K miles. Dealer suggests to flush and replace all fluids (trans, power steering, brake, radiator). The car seems to run perfectly and the resovoirs are clean and clear. Is this necessary? do the fluids really “break down” over time? Thank you for any assistance.

Yes they do especially coolant in radiator(loses rust inhibutors), brake fluid(absorbs moisture)and transmission. I have never heard of changing power steering fluid.

Your owners/maint. manual if avail should list time intervals or mileage (WHICHEVER FIRST) you should follow.

I agree, all the fluids have a life, check your manual. In general, they should all be replaced every few years if they don’t reach their mileage limits first. If the info is not in the manual, ask the dealer for the specific interval for each of the fluids.

I’d be inclined to drain and replace the oil and coolant, but not flush. Flush indicates using a chemical, and I don’t recommend this. For the other fluids, check the Owner’s Manual for time intervals. Power steering fluid recirculates as used and does not need replacing. Considering how hot it is in Pheonix the brake fluid should probably be drained and refilled, but it will need to be done proper to ensure that no air gets into the system.

Why does steering fluid never need changing? I changed mine after around 10 years, it was black.

The color is not an indication of its effectiveness. Power steering fluid is expected to last the life of the car. It normally darkens with age but remains effective. The auto manufacturers generally have nothing to say about changing it.

I don’t believe any fluid is really good for the life of the car, unless it’s a pretty short life. I would renew it every few (maybe 5) years to remove any contamination and maximize the life of the steering components. Fluid replacement is cheap compared to repair work.

Craig, I have to agree with you. Manufacturers have been trying to sell us on a maintenance-free car just as Bill gates tries to promote the paperless office, which is about as close as the paperless bathroom.

All fluids deteriorate due to use or time. And a nice car like an Infinity needs time based fluid changes to maximize its design life. Today’s plastic and aluminum radiators have a shorter life than the “long life” fluid in them. If you don’t drive much, changing coolant and transmission fluid & filter every 4 years is a small investment to maximize your car life. Differential oil and brake fluid should also be changed periodically.
I know I am preaching to the converted, but car manuals often leave a lot of stuff out, so the first owner does the absolute minimum to his “maintenance-free” car and the second owner ends up holding the bag and picking up the pieces.

Power steering fluid isn’t subjected to the heat and extreme environment that oil and tranny fluid are, and it doesn’t have the dissipation of anticorrosives that coolant has, and absorption of moisture doesn’t affect its performance the way it does with brake fluid, so it’s generally considered a lifetime fluid.

Having said that, it does cool and lube the pump and does lube the seals and spool valve, so while I wouldn’t consider it necessary I’d have to agree in hindsight that it might be a good idea. Especially in the Arizona heat. Perhaps if people did change it there’d be fewer pump failures.

I concede.

I wasn’t disagreeing with anyone, I’ve never seen a maker recommend changing the steering fluid, but I don’t think they’re projecting 10 years of use either.

Yup, it’s probably not the most critical thing on the car, but it can’t hurt.

BTW, check out this tread from another forum. We think this guy somehow got water in his PS fluid:


I agree with a drain and refill of oil, coolant and transmission fluid. I don’t like flushing of any of these fluids, but I would agree on flushing the brake system. I don’t agree on changing the Power Steering fluid. I’ve never had a problem with PS fluid, and I keep my cars for a looong time. Our 86 Tercel with 334,000 miles on it still has the original PS fluid.

So, are you going to be OK with keeping the same PS fluid in your tercel for the next 300K miles or are you eventually going to replace it? What do you think a reasonable interval is, do you wait until you have to do major steering system work to replace it? My car with 416,000 miles does not have the original fluid, it is replaced periodically; I certainly do not want to have to rebuild/replace steering components every 2 or 300K miles, that’s fairly expensive. I don’t think there is any real downside to replacing (not flushing) the fluid every few years, it’s easy and cheap preventive maintenance IMO.

Well said!! Fluids are cheap; mechanical components are expensive. Long term car ownership requires you to often rewrite the owners manual. You will note that the schedule usually only goes to 100,000 miles, with no mention of what might need to be done afterwards.