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Old 05-15-2020, 03:07 PM   #14
Spuds
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Quote:
Originally Posted by anticubus View Post
Cold oil is thicker and doesn't lubricate as well. Be patient but firm after you start up on a chilly day. Same reason you really shouldn't be doing WOT pulls or going much past 4000RPM before your oil is up to temp, the machine just isn't ready for hard driving.

Also, this is why all modern oils are multi-grade. The lower the number, the thinner on the viscosity scale it acts at a specific temperature. 0W-20 oil acts as a 0 weight at "low temperatures" (These are per-grade, but usually around -35C to -40C), which is going to be more viscous than its "operating temperature" grade (100C). Gear oil is usually 70W-90, so it's pretty thick, but a 70 weight at -35C is still going to be pretty thick compared to a standard 70 weight at 100C, it will just be slightly thinner than a 90 weight at -35C, just the same as the 90 weight side will be thicker than a standard 70 weight at 100C.
One note that isn't obvious there is that multiweight oil is still thicker at lower temperatures than higher temperatures. The number in front of the W represents the the theoretical viscosity of a single weight oil of the same thickness at the lower temperature if it were to be tested at the standard temperature.
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