Gear Oil: Conventional or Synthetic?

[Taco Supremo]

Hey guys,

I'm on my way to pick up my '15 from the shop after getting the 4.88's and lockers installed. Both Revolution Gear and ECGS recommend using conventional oil in your differentials at all times, not just during break-in. (As I was assuming) I reached out to both of them via email and they both confirmed again that, due to the more efficient heat transfer of conventional oil, its cushioning properties, and its water separation properties, it is recommended to use conventional oil in your differentials.

I'd love to hear everyone's input. It's a bit confusing. I ordered a 5 gallon pail of lucas synthetic 75w90 that it might return...

 

[gasman4u]

Hey guys,

I'm on my way to pick up my '15 from the shop after getting the 4.88's and lockers installed. Both Revolution Gear and ECGS recommend using conventional oil in your differentials at all times, not just during break-in. (As I was assuming) I reached out to both of them via email and they both confirmed again that, due to the more efficient heat transfer of conventional oil, its cushioning properties, and its water separation properties, it is recommended to use conventional oil in your differentials.

I'd love to hear everyone's input. It's a bit confusing. I ordered a 5 gallon pail of lucas synthetic 75w90 that it might return...

These guys know diffs, I have no doubt. Synthetic oil is more efficient at heat transfer compared to conventional however - this is known.

I don’t know what “cushioning” or water separation they’re talking about however. I’d want to have specifics about that before I say what I’m currently thinking.

I’d imagine a couple shorter initial break in intervals would serve you well using your in hand Lucas. I don’t know how Lucas compares to whatever other easily attainable and highly rated diff oils vs higher end Internet order oils personally. But there’s another forum for that.

HTH.

 

[Taco Supremo]

These guys know diffs, I have no doubt. Synthetic oil is more efficient at heat transfer compared to conventional however - this is known.

I don’t know what “cushioning” or water separation they’re talking about however. I’d want to have specifics about that before I say what I’m currently thinking.

I’d imagine a couple shorter initial break in intervals would serve you well using your in hand Lucas. I don’t know how Lucas compares to whatever other easily attainable and highly rated diff oils vs higher end Internet order oils personally. But there’s another forum for that.

HTH.

The response email from EGCS stated that, in their tests, the conventional oil transferred heat more efficiently from the R&P, resulting in the pinion being measurable cooler as compared to the tests with the synthetic oil. Their words.

The water separation was in reference to conventional oil and water separation occurring much quicker than in the synthetic, leading to more metal exposed to water should the vehicle sit for periods and not receive proper maintenance.

The cushioning, I'm guessing, is due to the conventional keeping a higher viscosity at operating temps. I didn't inquire further about that.

It's all very confusing. Lol

 

[gasman4u]

Check out lake speed jr and other tribologist guys on the internets/YT “university.” I’m not going to speak ill of what you’ve posted. Just that ecgs would be the sole source of saying conventional transfers heat better than synthetic.

Hopefully you’re changing diff fluid shortly after water ingress anyways.

The “cushioning” adjective is something I’m not comfortable addressing as I think it’s not common nomenclature. Ask about centistokes or centipoise. This would yield information that can be directly compared using industry established metrics and values. Otherwise, I have a hard time believing it. HTH

 

[CanadianRockyCruiser]

I use full synthetic due to cold temperature performance demands. Your use may vary. As I understand, synthetic doesn't turn to butter at -30C, and i frequently operate at extreme negative temperatures.

 

[gasman4u]

And herein enters the many benefits of modern chemistry, etc

 

[Taco Supremo]

I use full synthetic due to cold temperature performance demands. Your use may vary. As I understand, synthetic doesn't turn to butter at -30C, and i frequently operate at extreme negative temperatures.

Yeah, I'm an hour north of you and also running synthetic 75w90 (Lucas) for the same reasons.

 

[bjowett]

Here is the cushioning that is spoken of.

Selecting Oils with High Pressure-Viscosity Coefficient

Are synthetic oils (PAO - Polyalpha olefin and PAG - Polyalkylene glycol) better gear and bearing lubricants than mineral oils? At the heart of the issue is a property we refer to as...

www.machinerylubrication.com

 

[Willie G]

Here is the cushioning that is spoken of.

Selecting Oils with High Pressure-Viscosity Coefficient

Are synthetic oils (PAO - Polyalpha olefin and PAG - Polyalkylene glycol) better gear and bearing lubricants than mineral oils? At the heart of the issue is a property we refer to as...

www.machinerylubrication.com

Who knew?

I'm guessing for my 99.9% highway use that synthetics are still the way to go....