Strange Engine Noise !

98 Saturn SL1 - ~ 115 thousand KM (canadian, EH)
The engine makes a loud clacking noise when it is - 20 C. Only when I
start it up, and then it takes 3 - 5 minutes for the noise to go away.
Low on oil, no, using 10-40. Last winter I used 5-40 synthetic, turns
over better, but has a tendency to leak or weap.

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.

 

10W-40 is a bit thick for -20'C ( -4'F ) ????

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.

 

10W40 is too thick, especially for those temperatures. If 5W30 leaks, you
should fix the leaks rather than hurting your engine with too-thick oil.

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