I've had the car since it was new. Everything is original except the clutch (it is a manual). A while ago it developed a growl sound that it didn't originally have. It still runs fine. Doesn't sound like the transmission - more of an engine noise. I'm wondering with miles that high if I should switch to synthetic oil or if there is something else I can do to extend its life.

 

Does the noise occur all the time? Does it occur in neutral or only when in gear? With the clutch pedal pushed down or only when clutch is engaged? Is the noise constant or does it change with rpm?

Might not have anything to do with the engine or transmission. Bad wheel bearings can growl. I had a previous car with a growling alternator. I could never figure out what the noise was until my dad (construction equipment mechanic) identified the problem for me.

So, lots of possibilities but I don't think you'll get more than guesses without more information.
Good luck.

 

Occurs mostly when accelerating, or that's when I notice it at least. I'll have to try going into neutral but my sense is it is quiet. If the clutch is in, basically the same as neutral. Louder with higher RPMs. I have had bad wheel bearings in the past and don't think this is it. Thanks for the great diagnostic advice.

 

Idler bearing in the belt drive or a/c comp. bearing?

 

I do not hear the noise idling. Definitely when accelerating. It is independent of the A/C running if that matters.

 

🤔 ...

onomatopoeia really only goes so far: record the noise with your phone and upload it to youtube.