91' e30 318i shearing noise during idle
 

Hi all! i just bought my first e30 and indeed my first car. im in love with the cheeky 4 banger, and after getting it checked out at the local garage everything seemed great until today. i was looking over the car with my dad just to check for any missed errors and i noticed a pretty overwhelming shearing noise coming from the engine bay. Overwhelming once you hear it to start with otherwise it somewhat blends in with the idling of the car. Anyway i listened harder and noticed it was very high pitched so im assuming its coming from somewhere within the block, perhaps it might be a worn bearing? it sounds like metal on metal friction but as its high pitched im assuming its very quick. Otherwise im hearing the conventional tapping of the m42. Should i be worried about this noise? what could be the problem? any help would be greatly appreciated cheers!

What type of oil was the previous owner using?

im not entirely sure, but the oil smells ok and i not losing any. the noise has calmed a little bit so im not taking it as any major drama

Anytime you buy a car you should always change the fluids out. You never know what the previous owner was using or when they were last changed. You should use an approved oil and see of that helps.