[bshgto]

Originally Posted by Gregg

On the subject of oil viscosity. (weight) I have worked for a Caterpillar dealership for 42 years and have been performing failure analysis on engines over that period of time.
I have seen way more failures caused by using to heavy of oil during a cold start up than I have seen by using too thin of oil in the heat of summer. 15W (the W stands for Winter) Viscosity is tested at 0*F the high end viscosity (the 40)is tested at 210* F. it is fine to run 15W-40 oil however any Start below 20* F without block heater produces a high rate of wear and scuffing on Crankshaft Bearings. Will one or two stats fail an engine, most likely not, but it does start the process.

Always ran 5-40 syn. And in the winter with the block heater below 32deg. on a thermostat plug. When I was working and had to start the truck at around 10 deg. the plugged in the truck didn`t even know it was cold out. I guess the issue would be going to work and at the end of the work day having to start a stone cold diesel with 15-40 and like you said "start the prosses". So a 5-40 would seem to be the answer for most conditions.