Re: Gearbox oil

Posted by Owen_Dyneto On 2016/5/2 9:08:57

Just to emphasize, it's ESSENTIAL to use an EP (extreme pressure) gear oil in a hypoid rear axle. I'm a bit surprised at Pennrite's warning about yellow metals, the very first primitive EP gear oils used an additive sometimes called "SCL" for sulfo-chloro-lead and these were indeed corrosive to brass, copper, bronze, etc. but all of the EP hypoid gear oils I'm familiar with today no longer carry that warning and haven't for many years. For many years Packard recommended SAE90 in the winter and SAE 140 in the summer; I most often use Valvoline SAE 85W-140 year-round. I also have used it for decades in Packard standard transmissions and steering gear boxes and have had no problems. With that warning, I'd avoid the Pennrite product and go with a multi-viscosity EP product from one of the major gear oil makers, Mobil, Valvoline, Lubriplate, etc.

Others please correct me if I'm wrong but I don't believe there are any yellow metal parts in a Packard differential.