Quote:
Originally Posted by Pat
How many miles and track days were on that differential fluid? CSG recommends changing the fluid, "every 10,000 miles / 16,000 Km, 10 events, or when the driver can feel degraded performance of the LSD, whichever comes first. With the factory Torsen differential, depending on the driver, tires and track, degraded performance may be experienced after only 2 events."
I plan on changing the tranny and diff fluids more frequently in my ZD8 than I did my ZD6.
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Per my records, the diff fluid change was at 1526 miles. More than half of it was track miles. I have a feeling that the OEM fill is not of best quality, but might be wrong.
We have quite a bit of experience in differential fluids and overall performance in diffs on various cars. One key issue is temps and how the fluid fares in these hot temps. For instance, we were able to much improve the differential fluid life on my brother's NC Miata by adding a big cooler that never let it go above operating temps. This car was used in 2 day x 7 hour endurance races, and never missed a beat. The fluid was also still in pretty good shape when he replaced it as a precaution every 2 events, if I recall.
Going back to this car, especially a Torsen diff should keep doing well if the fluid still has the right viscosity, etc. 75W-110 is a standard that was released after 75W-90, and is WITHIN the 75W-90 (i.e. any car that recommends -90 is compatible with -110 as well per specs). That said, 75W-110 fares much better at high temps, and I see no reason why anyone using their cars at road course track would want to use the less stringent standard.
Use whatever brand you deem fit of course, but I've had good experience with the Amsoil fluids. Their 75W-110 should provide more protection at higher temps, and also degrade much slower, being optimized for higher temps and high-class synthetic.
Another example, GM recommends 24 hour track use as diff fluid change interval on their C7 Corvettes. It takes quite a few events to hit 24 hours; perhaps once a season or so is enough..
Finally, if this was a full on race car, I'd probably just put in a -140 weight fluid, as that's what most racing teams do. Oh well..