Hello again everyone! Love this site and all the helpful Volvo enthusiasts and nerds.
I've got another strange noise for ya'll to diagnose. Recently at operating temp after 15-20 min of driving I get a squeak/ light squeal at idle. Once driving it goes away. I removed the timing belt cover and can hear the noise coming from the top front pulley of the timing belt. Previous owner changed timing belt at 100k, now 168k on car. I'm unsure if pulleys and tensioners were replaced, but I'd like to assume so. First question: is that pulley in anyway related/lubricated by engine oil? (recent oil change with the possibility of 5w20 rather than 30--the shop receipt said 30 but the sticker said 20 so...great). My mechanic friend said a thinner oil in hot summer could affect that pulley as its connected to camshaft? That's over my head. Second question: if that pulley and/or internal bearing is the culprit what's the best action? another timing belt kit replacement with the whole shabang? The dilemma is spend $200-300 or whatever on the pulley or $800 on the whole thing with 70k on it.
Any help is appreciated, baby blue is going in to tomorrow for a diagnosis. Thanks as always!

 

Usually the replacement of the timing belt is the best time to replace the timing belt pully tensioner since it only last as long as belt itself and most likely the issue of the noise. Make sure the the sound is coming from the tensioner itself with a mechanics stethoscope. The pully tensioner does NOT get any oil from the engine as the only places the oil is supplied to is the oil pump and the camshaft's. Lastly keep in mind that the manufacture has specific oil minimum requirements which is full synthetic oil at 5w-30. If you put the oil with the 5w-20 in it with very few miles on it don't worry as a simple oil and filter change will do the trick.

 

If it has VVT on the intake, the pulley relies on oil.

Synthetic is not required