As the title suggests, my car is making a wurring noise that is proportional to rpms. It sounds to me like it is coming from the front of the engine (where the belts and timing equipment is, not the front of the car). It seems to be coming from my timing cover, but I am not certain. I just switched to Synthetic oil after using auto rx and then using dino oil for two changes to condition my seals. My car has 105k on it, and is in good shape (31 mpg highway). What could cause this? I was thinking timeing chain guides, but hopefully its a belt, maybe?

 

Alternator maybe?

 

So i did the screwdriver-to-the-ear test to pinpoint the noise. Put the tip on the timing cover, heard the noise, put the tip on the alternator, the noise was MUCH louder. So it sounds like the alternator is on its way out. Sorry to freak out, but I just envisioned my timing chain flying apart because of the synthetic oil, and a bunch of valves getting bent. I probably would have thrown myself off a cliff had the synthetic change at 105k caused my engine to become scrap metal. Guess the synthetic was just a coincidence. So tomorrow, in addition to out cv boots, I get to change an alternator. Lucky me!

 

I'd also check the a/c compressor as the same thing happened to me and it was the compressor.