The only descriptions I can find of GL-7 indicate that it has "improved
thermal stability" over GL-5. Most references say it has not yet been
approved by the API, and that the current API designation is PG-2, which
is a "temporary designation for heavy-duty truck and bus final drive
axles using spiral bevel and hypoid gears.". Apparently they are having
trouble with the "spalling test" part of the new standard, which is a
measure of how well the oil cushions against extreme pressure.
"Mystic" appears to be a synthetic oil, like Mobil-1 and Redline.
Based on those two facts, I'd guess your Mystic "GL-7" is probably OK in
a TR6 diff, but the only way to be sure is to try it.
Randall
"Bromiel, James E (Jim)" wrote:
>
> > Has anyone ever seen red gear oil? This weekend I replaced the Gear oil
> > in my differential. When I opened the quart I noticed the color was red.
> > I
> > checked both bottles, both red. The brand I bought is "Mystic". Is GL-7
> > all
> > right to use in a TR6 diff?
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