Gearhead Jim

2009 Coupe, A6, now at 51k miles
In another thread, I posted how the transmision and differential fluids had been replaced at about 7k miles, and then again recently at about 50k miles; using normal GM fluids. As tested by Blackstone Labs on the recent drain, the diff and tranny fluids were in excellent condition and could easily have gone longer. The engine oil analysis reports are also very good.

The same thing was done on the power steering- drain/refill (twice) around 10k, again at 51k, GM fluid. Today I got the results from testing the power steering fluid and they were not as good:

"We don't test a lot of power steering fluids, but of those we have tested, their average wear is listed in the universal average file. Averages are based on about 18,000 miles on the "oil". In comparison, there's more metal in your sample. Iron is from steel parts. This may just be accumulation from many miles of use. Silicon is probably from silicone sealers, hoses, and tubes. Insolubles show this oil was heavily oxidized from heat and/or use. Based on the slightly elevated iron and insolubles readings, we suggest about 20,000 miles next time for another look."

Here's some numbers
Mine 41k/Universal 18k:

Iron 187/22
Silicon 31/4

Insolubles 0.3, desired <0.1

This car has the Z51 power steering cooler, and does not get any HPDE or similar use.

On our tin grocery getters, I have the PS fluid changed at around 100k. Maybe I should rethink that.

Kvothe

Interesting. Thanks for the info

Are you changing these fluids yourself then sending to the lab or are you taking it somewhere and they change/send it out?

Gearhead Jim

Dealer did the work on engine oil, trans fluid, diff fluid.
Trusted independant shop did work on PS.
They all gave me the samples and I mailed in.

SpryGeezer

"There's many a slip 'twixt the cup and the lip."

John Harry

Good info, Jim. Thanks for reporting back to us.

Wayne O

Good on you for pursuing the analysis. Considering the lab's result averages are based on approximately 18,000 miles (of usage) and your results were based on approximately 41,000 miles I'd expect significantly higher levels of 'contaminants' from your test sample. There may be other variables as well....brands of power steering fluid used/tested, types of vehicles, operating conditions, etc. Also, I don't know what levels or ranges of 'contaminants' must be reached (and for what duration) before there's a practical, adverse affect to operability.

My take from your findings simply reinforces my long-held belief that clean fresh fluid/oil is preferable to older, dirtier fluid/oil. Whether it's motor oil, transmission fluid or power steering fluid IMO it's better to change oil/fluid more frequently than may be recommended by the manufacturer.

Thanks for making the effort to test the power steering fluid and for sharing the results.

LS WON

Don't forget Redline and Amsoil both have power steering fluids in synthetic.

EyeMaster

Funny to read this. My power steering fluid is leaking. Seems the fluid reservoir is leaking around it's edges where it's fused, but I can't really tell. Maybe the whole system is not very well designed and deteriorates. We'll see what happens to 20 year old C6's in the future.

PlanetZoom

Thanks for the info!

Tech

Clutch fluid analysis would be interesting!

fnsblum

One sample does not mean there is a problem. Iron tracks with miles and is the only metal that does. (source: Blackstone) My engine oil iron number has been up and down. The sample could have been screwed if they took it from the bottom of the reservoir. Do oven and do it yourself. Take it off the top. Later! Frank

PS:Forgot to ask what your procedure was for changing the oil?

Gearhead Jim

If I had a clutch...


I'm one of those shiftless types.

Gearhead Jim

We used the Service Manual procedure for the "flush":

Remove the return line to the PS reservoir, and plug the reservoir hole.
Put the end of the return line in a clean container (we used a clean plastic bottle).
With engine OFF, one guy turns the steering lock-to-lock while another guy keeps pouring PS fluid into the reservoir, never letting it go empty.

My sample was from the beginning of the "flush" because I didn't want new fluid to be mixing with the old. That may have produced more metal in the fluid, but IIRC the system is constantly circulating while driving and the car had been shut down within an hour, so I think the sample is reasonably valid.

I plan to do the next "flush" and sample at about 75k miles, we'll see how that works out in a couple of years.

LS WON

I took out the factory stuff a long time ago and put in Redline powersteering fluid in with no problems for years now. Also have a filter in line added.

BlueOx

Thanks for providing this...I have to admit that power steering fluid is generally not something I ponder much.

I'm curious if anyone has attempted to use the Ranger method to change out PS fluid? What do you use for PS fluid?

LS WON

Most people overlook the power steering fluid. Maybe it is the most neglected fluid.

Boomer111

Good information.

And this is the one fluid I admittedly fall short on regarding change.

I need to rethink also!

We all know that mechanical components will wear. The crucial thinking here for me is a cost effective wear timeline regarding changing fluids vs wear indicators. I think that the crux of this thread is poignant for reminding us about the power steering fluid which on my part is usually changed near 80,000 mile mark.

LS WON

There is no set interval on this as far as I know just like the rear end diff. If it's easy enough change fluid based on color and age.

C66 Racing

AMSOIL Synthetic Power Steering Fluid (Product Code PSFCN)

Jim - thanks for the info. Generally change out my power steering fluid once a year with an engine swap (I have two engines and have been swapping them back and forth). Just made me feel better knowing there was new fluid in there. Your info leads me to believe the effort has been worth it. And now I too am thinking about my daily drivers...