I have a 100k miles on my 2001 525i bimmer. Should I change the Fuel Filter? Is so where is it on the car? Also I need to replace my Alternator. If I let my car sit for a few days the battery looses it's charge. This morning when I went out to start my car it was DEAD. I checked the voltage with my meter and it indicated 5.9 volts. Another thing when the voltage drops my remote doesn't open the doors if I fiddle around with the remote long enough the alarm goes off. My car runs rough when I first start it up after charging the battery. It will run ok for a while and then it starts dieing at stop lights. This is why I'm changing the alternator. But I was told that I should change the battery also especially if it is not holding a charge. The Green, Yellow, Black indicator is BLACK. Can you recomend a good Battery other than dealer? Should I be looking at O2 sensors also? I have replaced the radiator and water pump but I noticed today when I removed the alternator that the upper radiator hose is leaking. This explains the whinning noise I get when I first start the car. Some one told me the fan is blowing the radiator fluid onto the belts. Makes since to me. I also found a leak under the power steering unit which contributed to the alternator problem. If anyone wants to jump in here and give me some advise I surely would appreciate it.