Differential oil alternative

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Jack9768

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Arrma RC's
  1. Senton 6s
Hi all, I just ordered all the drivetrain upgrades to run my Senton at higher speeds and I didn’t order any diff oil. And then I remembered that I have a quart of Mobil 85W-90 automotive gear oil in the garage, would that be a suitable alternative to RC diff oil? We don’t have a local hobby shop and the truck is just a backyard basher. I’m new to this so I don’t know what to use in it. Ask me how to rebuild a GM 10 bolt diff and what oil and I can talk all day. Clueless when it comes to RC weights. Thanks all!
 
Hi all, I just ordered all the drivetrain upgrades to run my Senton at higher speeds and I didn’t order any diff oil. And then I remembered that I have a quart of Mobil 85W-90 automotive gear oil in the garage, would that be a suitable alternative to RC diff oil? We don’t have a local hobby shop and the truck is just a backyard basher. I’m new to this so I don’t know what to use in it. Ask me how to rebuild a GM 10 bolt diff and what oil and I can talk all day. Clueless when it comes to RC weights. Thanks all!
It should be okay to run but the truck might handle a bit different than it did stock. It's been so long since I've used gear oil that I can't really compare it to any of the fluids I have now.

For short term it should suffice but I would try to order up some fluids, it never hurts to have a few different weights of fluid laying around.

I have had good luck with the Trackstar brand fluids, they are about $3-$4 a bottle, if you order direct from Hobbyking you can get 10% off with coupon code HOBBY10KING, $50 minimum for free shipping otherwise it's like $8. https://hobbyking.com/en_us/catalogsearch/result/?cat=&q=trackstar+silicone
 
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It should be okay to run but the truck might handle a bit different than it did stock. It's been so long since I've used fear oil that I can't really compare it to anything.
That’s why I was hoping to hear. The truck doesn’t do any racing and if set up properly the front and rear diff should really never exceed 120 degrees. What changes might I expect handling wise?
 
That’s why I was hoping to hear. The truck doesn’t do any racing and if set up properly the front and rear diff should really never exceed 120 degrees. What changes might I expect handling wise?
It depends if the gear oils viscosity is more or less than the stock diff oil.

But this will do a much better job explaining it than I ever could.

30230
 
85W-90 is 85w when cold, 90 when hot.

This would suggest it's relatively light:
https://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid

90W: 13.5 - 24.5 cst@100C

100C is boiling temp for water, so probably won't get that hot. Regardless, that's a pretty low cst rating when compared to 2,000cst-500,000cst stuff we use in diffs.
 
Automotive oils and greases aren't close enough in viscosity (cSt) compared to that of silicone diff oil that would normally go in there.
Mobile 85w-90 only has a viscosity of 184 cSt @40C

30231
 
I'm fond of Team Associated brand but it's all relatively the same.
I try to keep 1k 10k 30k 60k 100k and 500k on hand, and will then mix them together to make pretty much any viscosity between 1000-500,000cst using this calculator https://www.widman.biz/English/Calculators/Mixtures.html
 
I know this is an old old thread, but I've been considering either Motor Honey, or Lucas synthetic oil stabilizer in EXB diffs that have the LSD plates set to full effect. But ONLY with the aluminum upgrade diff cups. Plastic doesn't fair well with anything but silicone. The O-Rings would do just fine as they're silicone and resistant to anything petroleum based. Silicone is not a good lubricant for metal gears at all. You could still tune by adding some automotive gear oil to thin that thick oil additive whichever diff you want. For me, I'd keep it all thick at the front, add a quarter to half gear oil in the center and 3/4 gear oil at the back diff. I tune my diffs to compensate for when the center throws too much power up front, the thicker stuff up front will force it back to balance it like AWD. It works too. The model won't spin out (fishtail) but rather handle like it's on rails.
 
I place a daub of Bel-Ray Moly/Graphite assembly lube in the with the silicone diff oil.
Spider gears get lubed and wear becomes nearly non existent.
That's cool. Shouldn't hurt. For regular diffs, I use plenty of teflon shock seal grease (aka green slime) on the O-Rings, then Lucas Red & Tacky on the underside of the Mugen shims, (where they rotate against the aluminum diff cups I use) apply teflon dry lube on all the satellite & sun gears with a paintbrush, then fill with desired weight silicone diff fluid. So smooth.
 
Even in my EXB LSD diffs, went to a thinner fluid, tho still placed a daub of the Bel-ray in there as well.
On season two running this way & all is working fantastic. Diff are very consistent and I know there is lubrication happening.

For those who may not know or realize ... SILICONE is a GARBAGE lubricant on anything metal on metal !!!!!!!!!!!!
Only reason it is used in differentials or center diffs is the stability of the viscosity with extreme temp changes.
 
Even in my EXB LSD diffs, went to a thinner fluid, tho still placed a daub of the Bel-ray in there as well.
On season two running this way & all is working fantastic. Diff are very consistent and I know there is lubrication happening.

For those who may not know or realize ... SILICONE is a GARBAGE lubricant on anything metal on metal !!!!!!!!!!!!
Only reason it is used in differentials or center diffs is the stability of the viscosity with extreme temp changes.
You're right. On top of that, the gears are porous steel. Maybe sintered. Definitely not machined. Silicone is great for plastic, but only serves to slow the diff function in these for sure. The gears in there turn the fluid grey very quickly because the silicone isn't doing anything to actually lubricate them. That's why I thought about the thickest petroleum product (without being a grease) I could think of for LSD EXB diffs. Motor Honey. Best protection. The LSD kinda works hydraulically, so the LSD wouldn't function if they were completely filled with just grease, and super thick viscosity silicone diff fluid in them isn't near as necessary in lighter model builds.
 
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