Re: Index of Crossfire problems and repairs
found this regarding viscosity:
"
The difference is the viscosity when hot.
Oils without the "W" do not have a cold viscosity test. 75W gear oil has a maximum viscosity of 150,000 mPa.s @ -40°C. (I know, meaningless numbers for most of us, except that the test is at -40°.)
90 wt. gear oil, including 75W-90 has a hot viscosity range @ 100°C of 13.5 to 24 centiStokes. 140 wt. has a 100°C viscosity range of 24 to 41 centiStokes. Again more less-than-meaningful numbers, but note that there is a range of viscosities and that 140 might be much thicker than 90 when hot. Interesting note...90 wt. has about the same viscosity as a 40 wt or 50 wt motor oil. Motor oil viscosity grade numbers range from 0W to 60, and automotive gear oil numbers range from 70W to 250--75W wt. gear oil is about as thick as 10W or 20 wt. motor oil.
Is thicker better? Not necessarily. You need the viscosity the design engineers specified for proper flow into the parts. Excessive viscosity can result in churning of the oil and the generation of additional heat. "
and much more:
https://www.rv.net/forum/index.cfm/f...print/true.cfm
Last edited by phil alvirez; Aug 25, 2019 at 01:01 PM.