Quote:
Originally Posted by ksteckba
You added your own thoughts about needing thicker oil when then engine is cold...
Don't worry though I received your visitor message as well.  |
When the engine is cold the clearances between the bearings increases. Oil viscosity is very closely tied to the bearing clearances. When building race engines you need to adjust your oil viscosity according to clearances set by the builder. The same effect is happening when the engine is warming up. You have a greater bearing clearance that requires a higher viscosity oil to property lubricant the surfaces until operating temperatures are met. The higher viscosity oil helps to maintain oil pressure and flow across the bearings (they take this into consideration when selecting the 2 viscosity values on the oil). Now if you are in extremely cold climates like some, the oil is too thick when cold and changing oils or warming before startup is needed.
(Not that experience speaks for itself, but I have run an auto repair shop for about 15 years and built 100+ engines. I’m not just talking out my ass.)