What gear oil are you running in your Eaton trutrac?

According to Eaton….

• A quality, petroleum-mineral based, GL5 rated 80w-90 gear oil should be used.

Any recommendations?
Thanks

OK, I have standard Ford limited slip unit, but..Im really, really impressed with Royal Purple, I now have it in every limited slip and manual trans that I own.

I've run them for many years and used to know an eaton engr through work. I run 85w140 non synthetic because it raises the bias ratio. Years ago you could call the eaton tech line and they would tell you the same thing.

I went with Shell 85w140 from a recommendation on "bob is the oil guy" forum. If you want to learn about oils, spend some time over there.

The standard Ford LSDs are clutch-type, whereas the Torsen and TrueTrac are helical-style. For helical-style LSDs, there is such a thing as "too slippery" gear oil, which reduces the Torque Bias of the diff by lowering the force the helical gears can develop against each other. Both Torsen and Eaton-Detroit recommend non-synthetic oils for best performance. Also, don't add "friction modifier" fluid to helical LSDs. I've read that some companies add friction modifier to their gear oils (may be certain versions), so be careful of that.

blacksheep-1 said:

OK, I have standard Ford limited slip unit, but..Im really, really impressed with Royal Purple, I now have it in every limited slip and manual trans that I own.

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I put Lucas in mine. Seems fine. But, I've got a real good deal on Liqui-moly going, so that's next.

Redline lightweight shockproof is good mixed 1:2 with Motorcraft 85W90 or Valvoline.

I use Redline 75w-140NS. It doesn't have any friction modifier.

steveespo said:

Redline lightweight shockproof is good mixed 1:2 with Motorcraft 85W90 or Valvoline.

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What’s the interval you drain that?

Bouncing Soul said:

What’s the interval you drain that?

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10-12 hours

I like Miller's Oils, they have a 90-140 that worked really well in mine. Many Indy Cars, GT and Endurance cars are using it.

I have a fresh build true track with 3.55's i'm running Lucas 80x90 in for now. I have about 600 miles in it and were about to do some HPDE events next week with it.