Community Forums

baloo · 02-18-2013, 09:09 AM

I dumped out the oil from the rear end of our 38PST (Diesel) -- and measured about 12qts.

I was planning on replacing it with Valvoline 75W90 synthetic GL-5 "extreme High/Low Temperature Protection." The bottle also says "Limited Slip" on the front.

The fine print on the back goes on to say "Meets or exceeds the performance req'mts for US Mil Spec MIL-PRF-2105E, ... and API services GL-5 and MT-1.

It also says "Recommended for all standard and limited slip hypoid differentials...."

Even though it says "recommended for all standard AND limited slip diffs...", WHAT BOTHERS ME ARE THE WORDS "Limited Slip" and that the Mil Spec is MIL-PRF-2105E" instead if "2105D" that I've seen others specify for this vehicle.

Am I making too much out of the Limited Slip and Mil Spec 2105E?

Thanks for any inputs.

baloo · 02-18-2013, 01:49 PM

I'm doing a dfollow-up to my question. I had also posted this question on the Roadmaster website on iRV2. From my own research as well as the info from HeapBigEngine, here is the answer.

Quote:
Originally Posted by HeapBigEngin

Lubricants designed to work in a "limited-slip" application are blended as such to be compatible with the clutch materials and/or clutch discs normally included as part of the "clutch pack" design of a limited slip differential setup. A standard differential does not have these lubrication requirements. Use of a standard lubricant in a limited slip application can result in loss of the limited slip capability over time....or worse. Don't want to do that. However, use of a lubricant compatible with limited slip in a standard differential is fine....just like the bottle says. The 'E' designation should merely tell you that the fluid meets a higher test standard/requirement than 'D', since it also meets the higher limited slip fluid requirement.

Thanks Heap BigE. Good to know about using ltd slip oils in non-slip differentials.
Yep, I went on line to check the differences in the Mil Specs, and here's a quote from the Lubrizoil website (Untitled Page

API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.
API Category MT-1 designates lubricants intended for non-synchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting API MT-1 provide protection against the combination of thermal degradation, component wear, and oil seal deterioration which is not provided by lubricants meeting only the requirements of API GL-4 and API GL-5.
MIL-PRF-2105E this specification released in 1995 combines the performance requirements of its predecessor (MIL-L-2105D) and API MT-1. MIL-PRF-2105E maintains all existing chemical/physical requirements, stationary axle test requirements, field test requirements and data review by the Lubricants Review Institute that were required under MIL-L-2105D. It also adds the stringent oil seal compatibility and thermal durability test requirements under API MT-1. MIL-PRF-2105E has been re-written as SAE Standard J2360.
SAE J2360 standard is a new global quality standard that defines a level of performance equivalent to that defined by MIL-PRF-2105E, a U.S. military standard for approval that was not available to oil blenders in all parts of the world. It includes all of the most recent axle and transmission testing requirements identified in API GL-5, API MT-1, and MIL-PRF-2105E including the need to demonstrate proof-of-performance through rigorous field testing.