so ive noticed the past few times ive started my truck in the cold...i drive to the coffee shop and i get out and theres a clatter commin from the engine...the truck isnt warmed up yet. is this normal? i dont know how to explain the noise other than a clatter. and once the truck warms up its gone

thanks guys

 

You may wont to go to a 5w 40w. In cold conditions, under 40f, the 5w 40w oils are much better for your engine than a 15w 40woil.

 

If people would read their owners manual they could read the part where they say to use winter weight oil any time the outside temp get at or below zero in between oil changes. My self I change it any time it will get below 10 above zero as 15w40 dino oil starts to get thick when the temp drops below freezing = 32 degrees!

Also dino oil pour point is not the same engine oil flow, oil flow point is IIRC around 25-30 degrees above the engine oil's pour point.

 

so its just the oil is still thick? now if i use 5-40 will it hurt. because we are having weird days. some are 20 some are 40-50. will it hurt if i keep using 15-40? i just wanna do the best for my cummins, i dont wanna hurt her

 

it wont hurt it. . .all that is going on is the5-40 is a bit thinner under cold temps than the 15-40 to help with startup. once the oil is warmed up it reacts the same way as the thicker stuff, however the oil will circulate quicker when cold.

with temps being in the 50's I wouldnt worry about it, but when the temps get a bit higher, mid 60's is when I would go back to 15-40.