Is there anything in the valve train that can change noises when it warms ?
Does it have forged pistons ? they can clack.
Maybe a wrist pin ?
Ultimately the engine still has extended warranty, so I would like to have it fixed before something serious happens. Do Saturns have a history of engine problems ? Already had the transmission valve body replaced so I might have a lemon.
The timing chain is tensioned by oil pressure on a cylinder. Thick oil will be slow to load the tensioner. Should not the engine run with 5W-30 per factory spec.?
If the chain is run long and/or at high speed damage can be done.
I would guess that the noise may be lifters/lash adjusters starved for lubrication..
...can the 0W-30 be used in temps that cold? I'm not familiar.
I'd run Mobil 1 0W-30 or 0W-40 in that temp. range.
Not many modern cars recommend 10W40 in winter because it is not designed to be used much below 40F - it gets too thick, as others have mentioned.. The first thing I would try is changing to the oil recommended in your owner's manual - probably 5W30 for winter, if for no other reason than you will likely void your extended warranty by using non-specified lubricants.
Dana
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