The other day Amsoil released another White Paper study where they put their Severe Gear 75W-90 Gear Lube up against 13 other popular brands including:

Castrol Syntec 75W-90
GM Synthetic Axle 75W-90
Lucas 75/90 Synthetic
Mobil 1 Synthetic 75W-90
Mopar Synthetic 75W-90 with Mopar LS additive
Pennzoil Synthetic 75W-90
Red Line Synthetic 75-90
Royal Purple Max-Gear 75W-90
Torco SGO Synthetic 75W-90 with Torco Type G LAS additive
Valvoline SynPower 75W-90
Castrol Hypoy C 80W-90
Pennzoil Gearplus 80W-90
Valvoline High Performance 80W-90

Of the 14 fluids (including Amsoil) 12 of them failed to meet the specs of at least one test performed.  The crazy thing is some of these fluids were already out of spec before any testing.  Lucas and Royal Purple exceeded the spec they were claiming to be before the Shear Stability Test, making them thicker than what was advertised.  After the test, Lucas had worn enough to now be within the spec, but Royal Purple failed again and was now too thin.  A bunch of other interesting results here and it is expected to shake up the entire Gear Lube market as people realize and see that the fluids they are using are not meeting the specs and demands that these manufacturers are claiming that they do meet.

I don’t have this posted on my Web Site yet, but you can DL the PDF file from it and read it at: http://www.technilube.com/brochures/g2457_gl_white_paper_0907.pdf. Some of the results here were performed in the Amsoil lab, others at an Independent lab, but the testing was nothing out of the ordinary, just standard ASTM tests that any lab in the world can recreate.

Motorcraft fluid wasn’t included because they were testing 75W-90 gear lubes, and all current Ford applications are using thicker fluid.  But based on this, you can guess what the results may be.  If you want, you can zip to the end and see how each scored and the number of tests each failed.  Have fun reading!