Rear Differential 75w85 vs 75w90 - Any Benefit Either Way

[Impatient]

Plus the Gear 300 is extremely shear stable. I haven’t seen any KRL results for any 75w85s, but considering that only HPL and Motul were under 2% mechanical shear on 75w90, it’s hard to imagine there’s any 75w85s with better viscosity retention…

Uh, correction, the Amsoil SVG had the lowest KRL in your tests. Or am I misinterpreting the tables?

 

[martinq]

Uh, correction, the Amsoil SVG had the lowest KRL in your tests. Or am I misinterpreting the tables?

You are correct!

Thread 'Mega 75w-90 testing thread!'

Jan 15, 2024

@ford250 @SNWMBL @Impatient and maybe more (sorry, it’s been awhile!) contributed samples for this test.

We’ve imported the other 75w90 tests from my other thread here, and also add these 75w90s:
Shell Spirax
Subaru HP
Ultra Plus (cool clear bottle!)
AC Delco
Valvoline Synpower
Ravenol VSG
HPL non-CC Diff Life

Somehow, I misplaced the Motul Motylgear so that didn’t get submitted. Apologies. Lab also included foaming results, but I have not read the ASTM method yet to determine the pass/fail criteria. Looks like vsl= visual, and tr= trace. Other than that, here’s...

• SubieRubyRoo
• Replies: 113
• Forum: Gear, Transmission, Hydraulic oil analysis

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[Impatient]

I have 3 vehicles (complaining not bragging). I have Motul in 1, SVG in the 2nd, and HPL in the 3rd. So I wasn’t trying to diss any of those.

I based the decision in #2 & #3 on Subi’s Mega thread. #1 has had the Motul in for awhile, since before the thread, but maybe only 15-20k miles, if that. #3 was supposed to get 75w85, per Ford, but got the HPL 75w90 instead. Ironically, it will see colder start-ups than either Subaru, as they probably will never leave Texas under my ownership.