I recently took ownership of a 325es, 210k miles on it, seems to run well but I have a couple of questions.
The previous owner didn't have service records or the bmw owners manual for the 3 series, so 1st thing I'm wondering is which grade of gas makes the most sense? I have available to me - 87, 89 and 91. I have been using 91 since I don't know what is best for the engine. I don't have any performance chip or anything of that nature installed, and I probably won't put one in until I've sorted out any other outstanding issues with the car if I do it at all.
Second thing is that there is a high pitched whine when i'm running in 4th or 5th gear between 2000 - 3000rpm, if i turn the wheel or stop accellerating and let the car coast it seems to go away.
Anyone have any idea what this could be and whether the repair will be something that has to happen quick, is it expensive and can it wait awhile?