Hey Guys

Recently, I have been getting strong vibrations in my steering column when turning the wheel AT IDLE. Furthermore, I can feel an almost "percolating" feeling in the brake pedal at stop lights for the first 10-15 minutes of driving. (I don't know if this is at all related.)

So, the first thing I checked was the power steering fluid. The level was fine, but I noticed that the previous owner put ATF oil in the system instead of the Pentosin CHF 11S fluid. I have searched the archives and saw that the recommended "fix" was to slowly siphon the reservoir and replace the ATF with the CHF 11S fluid.

I did this once yesterday and thought I noticed a reduction in the "vibrations" at idle. I did it again this morning (as the fluid was still very red), but the PS pump started groaning and the vibrations were shaking the entire car (even without turning the wheel). I eased the car around the street several times and eventually the vibrations and groaning went away. The fluid is again very RED as the CHF 11S mixed with the remaining ATF.

My first question is if all '95 540i's use CHF 11S, since the pump did not seem to like its first exposure to it. My second question is if you think I did any damage to the pump by waiting so long to change the fluid (about 6 months!)(When the car has been driven about 10 miles, the steering works perfectly.)

Luckily, I don’t see any major leaks in the hoses like a lot of 540is have (knock on wood!)

The car is a '95 540i 6Speed.

As always, thanks your input.
Andrew