I asked my local commercial Mobil distributer and he claims this tiny type is the way Mobil classifies ALL their lubes for inventory purposes.
Yes, it's full synthetic.
I doubt it would meet the Eaton Dana approval list for their 750,000 mile extended warranty with 500,000 mile drain interval if it wasn't a beefy synthetic.
The spec sheet also gives it away. Notice the low temp and high temp performance, no conventional gear lube could cover such a wide temp range.
I rest well at night running this product in my expensive Eaton Dana HP-40 tandems. It really is a good product, though unknown outside commercial trucking, industrial, and mining circles.
I've posted previous responses warning not to use it in any limited slip application, so you've paid attention. SHC would work fine in a mechanical "locker" though: example PowerTrax NoSlip and LockRite, Detroit Locker, etc.
If you require GL-4 lubes, you can get Mobil MobilTrans SHC 50. It's a companion product designed for all GL-4 stickshift transmissions, from light duty to HD truck. I run this in my HD trucks and have used it in my personal stickshifts that required a GL-4 lube: excellent results.
Jerry
