Gear Oil without Limited Slip additives for TrueTrac, Helix, Torsen, Grip Pro differentials

Greetings, I am installing a Torsen-style, helical gear limited slip differential and have been researching the right gear oil to use.

The manufacturers almost universally say to use dino conventional oil with no limited slip modifiers. Eaton Detroit TrueTrac has more recently "allowed" the use of synthetics, but still say not to use LS formulas. This way their stuff can be compatible with automakers that require synthetic in their differentials for the benefit of the gears and bearings. The idea is that synthetic and/or LS formulas are more slippery and reduce the torque bias of the helical LSDs. Nobody wants that.

Here is a list of what I came up with for gear oils without limited slip additives. It is not easy to find synthetic gear oil without the LS! I put the cheapest places that I found in the "Where to Buy", but it can be found in multiple places. Also, I put the cheapest size that I found (Qt., Gal, etc.). Lastly, there are many more conventional oils without LS than I listed, but my main goal was to get all the synthetics in one place.



I am leaning toward using the Mobil Delvac 75W-90. I may decide to break in the new gears (which are going in at the same time as the Nitro Helix) on conventional, and then switch to Delvac and see if I can feel any loss of torque bias on the differential. Anyone have any opinions on that? What do you use?

 

What does the manufacturer of your new differential specify for oil?

 

Richmond "richgl5" or valvoline in the white quart bottles is what powertrax said they use.

 

Nitro does not specify anything, but it looks like a rebrand of the Powertrax Grip Pro. Powertrax contradicts itself in the installation instructions:

"Use any gear oil without friction modifier", then later in the same document, "IMPORTANT LUBRICANT NOTE The Powertrax® Grip Pro™ limitedslip differential design uses helical cut gears to transfer power to the wheel with the most traction. Always use an 80W-90 mineral/petroleum based gear oil with at least a GL-5 rating. Synthetic oil and oils that contain friction modifiers are NOT recommended."

 

Thanks! I have the Valvoline in my list at the top. I just looked up the Richmond RichGL5 and it says it has friction modifiers, so I will pass on that one. Also, the Mobilube I listed is more of an industrial lube and the specs look better to me than the Valvoline. To top it all off, ECGS only recommends Lucas 85W-140 for any and all differentials, but it has LS modifiers in it.

I am sure that I am overthinking this and it probably does not matter much, as long as you change the oil often enough. I will avoid LS additives though, so that rules out Lucas, Amsoil Severe Gear, and most of the synthetics.

 

Also, just out of curiosity, check out Dino motor oil Castrol GTX 10w40 and compare viscosities with 75w90 trans oil. No limited slip additives, good wear protection package. $20 for 5 quarts on Amazon.

 

If you are feeling very fancy, you can use motor Redline 0w40 for lower warm up times in winter.

 

Auburn says the same thing but I’ve been using nitro synthetic gear oil with the additive for 1000s of miles and it’s still working fine. I can feel it lock up when it should. Sometimes I think it might be locking up too much. Maybe that’s why they say no synthetic. I’m not sure of any long term effects, but I did the same in my 2010 with the Auburn for over 50k miles and it still worked fine.

 

Oh man, you just opened up a can of worms They may have the same viscosity, but they are made for different purposes. The gear oils are made to resist shock load, water, tarnishing and a bunch of other stuff. The motor oil needs to resist being diluted or washed away by the gas. You are right that they both need to provide wear protection.

 

Thanks for sharing real world experience! Is the Auburn a cone style clutch LSD? They don't offer anything for my 1st Gen.

 

I am doing my next differential and transfer case oil changes with motor oil and will report if something blows up. I used to be on the ‘it should have the manufacturer approval’ team.

 

Cool, you are a pioneer! No progress is made without people like you. But I don't think you should do this particular experiment, ha. I have been researching gear oils for almost a day, so I know what I'm talking about...

 

In the old days, a factory fill for the manual transmission was engine oil. I’m not pioneering anything here, just using good old pre-marketing era knowledge.

 

I've run amsoil synthetic in my powertrax it's whole life without complications. My figuring is worst case the thing doesn't lock up as well, and it's an oil change away to fix that, and in the mean time the gears and diff will be "better" lubricated. No issues in the past year/25k miles.

 

Yeah, that makes total sense. All the gears should be well protected with that stuff. But I want it to lock up real good! I can't find any test -even seat of the pants test - of dino vs synthetic - with and without FM. That's why I think I may start with dino for the break in and then switch to non-FM synthetic. If I can't feel a difference, then try some of that Amsoil Severe Gear with the FM. It may not make much difference.

Here's a study of gear oil that is pretty interesting.
http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf

 

Yes it’s a cone style and I completely missed that you had a 1st Gen.

 

No worries. I would think that a friction modifier would be a requirement on those. Do they specify no synthetics?

 

I also run Amsoil synthetic Severe Gear 75w90 with my Powertrax and it Performs flawlessly.

 

Auburn says no synthetic oil like the others but to put in the additive. I used the synthetic that says it has additive and still put in a little additive to be safe.

 

Check out redline NS (no slip additives) gear oil. It's meant for manual transaxles with hypoid gears.

 

Fwiw Torsen brand differentials don't care what fluid you feed them. Torsen simply specs whatever the ring gear specs.

I have no insights on Eaton.

 

Yeah, I was checking that one out too. I have also had good luck with Liqui Moly in another car - it is quality stuff. A lot of good choices out now. I will report back if I learn anything interesting while testing dino vs synthetic. Thanks to all for the input. I feel better about using the Amsoil if I decide to go that route too.

 

Lucas is another option that is very similar to the white valvoline stuff. Though i have heard but cant verify that the lucas is noisier in diffs.

 

So im running the revolution 5.29 gears with the Powertrax Grip Pro in the rear they put regular mastercraft 80w-90 in it from
O'Reilys and im wanting to run something better I run the shit out of my truck offroad and on what should i put in front and rear or same in both?

 

AMS oil for sure. I run the synthetic severe duty and 2yrs layer still great

 

Motor oil doesn't have the shear strength to deal with the hypoid pinion and ring gear contact. The pinion is offset from the axle axis so the gear faces don't so much mesh in the traditional fashion, but are constantly sliding across one another. That's why they emphasize the difference with numbers like 75w90 vs 10w40 even though they're similar viscosities.

Inside the torsen shouldn't care. Honda has run torsens in some manuals with basically a special 5w30 for trans fluid.

Spez: incorrect term

 

If you think that some ‘magical’ fluid can save a poorly mechanically designed mechanism, you are welcome to continue to believe in it.

From the formulation standpoint, there is nothing special in the transmission oil that clearly separates it from the motor oil. The marketing and markups are different though.

 

Not the transmission/tc. I ran 10w-40 in the 5 speed tacoma for years. I'm talking about the ring and pinion in the diff. Iirc a GL5 fluid has a lot of a zinc-based additive that bonds to the steel so it can act as a sacrificial layer to handle the sliding under pressure far more than just a liquid can do.

 

Hypoid not helical. You'd think I could keep those terms straight. Anyway a good read. Please don't put motor oil in the rear end. Bad things happen.

https://www.engineeringchoice.com/what-is-hypoid-gearbox/

I made the mistake once of putting GL5 in a manual gearbox that needed 75w-90 GL4 and I can verify 100% its not snake oil. That oil is so gosh darn slippery the truck absolutely required double clutching every shift from the very first drive down the road. Those syncros gave basically zero friction. Couldn't get it out fast enough. But you need that owl snot for the diff ring and pinion to survive.

The additives mentioned like for limited slip clutch packs make it even more resilient to losing the fluid layer under pressure to keep the clutches from chattering in a turn. The less you go into that territory the better for the torsen to work right.

 

I've also had manual transmissions that called for GL4 and warned against GL5 for both slipperiness and for harm to brass synchros.

Redline MT90 is a GL4 that works excellent in Toyota pickup manual transmissions.