I had a quick question on the compatibility of Pentosin CHF11S in my 1990 300E. I was under the hood for some other maintenance, and discovered that my PS pump was whining. Being in a small town, I opted for what was available, and put ran two 2 liters of Pentosin CHF11S into my system. I had a four-hour trip in front of me, so I wanted to alleviate the pump whine asap, but I wonder now if I did more harm than good. I would certainly appreciate any opinions on the matter?

 

The garage where I bought my 2nd hand 2006 C220 told me that had done a "gold service" before I bought the car. Upon getting it home the power steering oil was basically off the dip stick and was chocolate in colour instead of red. I sucked as much as I could out and filled it with the cheapest auto transmission oil I could buy (£4 a litre) and it felt better. After a week I changed it again to get the rest of the chocolate sludge out, filled it up with the rest of the £4 ATF oil and its been fine for the last 10K miles. If you run it dry it will damage the pump. If you want my opinion I think it is better to change the oil for cheap stuff every 6K miles than buy mega expensive oil and leave it in there for 20K miles. You have done good, change the steering oil regular and it will be fine. Regards Gary (UK)