250F isn't unusual for differentials or transaxles if driven spiritedly, in my experience. Not exactly desireable either.
ACDelco 75W-90 Syn Axle Lube, 13.7k mi OCI, 34k mi
- Thread starter Emperors6
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Assuming the RL 75W90 virgin KV@100*C of 16.4 cSt,it would be interesting to observe if this 5000km sample falls into which of the following crudely classified stages of :
a )Stage 1 > Shear-stable at KV@100*C of 16.3 to 16.5 cSt;
b )Stage 2 > Shear-thinning from 16.4 cSt to lowest possible of say, 15 cSt;
c )Stage 3 > mild shear-thickening from lowest 15 cSt to 17 cSt;and
d )Stage 4 > severe shear-thickening from 17 cSt to a maximum of 25% at 20.5 cSt or beyond.
Await your UOA to see if it's sensible speculating a Stage 2.........
a )Stage 1 > Shear-stable at KV@100*C of 16.3 to 16.5 cSt;
b )Stage 2 > Shear-thinning from 16.4 cSt to lowest possible of say, 15 cSt;
c )Stage 3 > mild shear-thickening from lowest 15 cSt to 17 cSt;and
d )Stage 4 > severe shear-thickening from 17 cSt to a maximum of 25% at 20.5 cSt or beyond.
Await your UOA to see if it's sensible speculating a Stage 2.........
Thanks. The UOA was received by Blackstone. I'll post a new topic as soon as it comes. I've asked my mechanic if he put in RL 75W90 NS or non-NS. I'm confused, since I thought he put non-NS (with friction modifiers), but on the sample bottle he wrote "RL 75W90 NS." I need to know to figure out the spec viscosity.
As for the temperature, the highest I saw in the rear diff on the new RL Heavy Shockproof was 260F. I can't tell if it's because it's thicker, or I pushed the car more (plus a hot day). Unfortunately, it's the upper range of the crystal thermal strips, so I can't see if it went even higher. I've bought the ones that go from 260-350F for the next event. Though, I didn't get the DIC warning. This means it stayed below 300F, as I understand, that's the trigger point for the warning.
As for the temperature, the highest I saw in the rear diff on the new RL Heavy Shockproof was 260F. I can't tell if it's because it's thicker, or I pushed the car more (plus a hot day). Unfortunately, it's the upper range of the crystal thermal strips, so I can't see if it went even higher. I've bought the ones that go from 260-350F for the next event. Though, I didn't get the DIC warning. This means it stayed below 300F, as I understand, that's the trigger point for the warning.
GM recommends 75w90 for Corvette for track use. It also recommends changing the fluid before and after the track event. I would change right after track event regardless of what is used. All the 75w90 axle lube that I have seen is suitable for limited slip. No additive is needed. GM doesn't call for additive anymore.
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Originally Posted By: CapitalTruck
GM recommends 75w90 for Corvette for track use. It also recommends changing the fluid before and after the track event. I would change right after track event regardless of what is used. All the 75w90 axle lube that I have seen is suitable for limited slip. No additive is needed. GM doesn't call for additive anymore.
OEM may be calling for GL5 75W90 in CTS-V, but it seems RL 75W90 AND GM's of appropriate part# are not holding well in OP's UOAs'.
Quote:
Switched to fill of RedLine Heavy ShockProof since mechanic said the fluid looked bad at pre-track inspection.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4168363/RedLine_75W-90_GL-5,_3k_mi_OCI#Post4168363
GM recommends 75w90 for Corvette for track use. It also recommends changing the fluid before and after the track event. I would change right after track event regardless of what is used. All the 75w90 axle lube that I have seen is suitable for limited slip. No additive is needed. GM doesn't call for additive anymore.
OEM may be calling for GL5 75W90 in CTS-V, but it seems RL 75W90 AND GM's of appropriate part# are not holding well in OP's UOAs'.
Quote:
Switched to fill of RedLine Heavy ShockProof since mechanic said the fluid looked bad at pre-track inspection.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4168363/RedLine_75W-90_GL-5,_3k_mi_OCI#Post4168363
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