Re: Severe diff noise

Posted by Owen_Dyneto On 2012/5/2 14:50:54

I doubt very much that the viscosity of the gear oil was the issue; for many years Packard recommended 90W in the winter, 140 or 160 in the summer.

Remember that the differential uses hypoid gears and unlike the transmission must have a gear oil with "extreme pressure" or EP properties. The EP gear oil is also satisfactory in manual transmissions with the possible exceptions of the very early ones that use yellow metal (bronze, brass) components. But a simple gear oil without EP additive is extremely damaging to a hypoid differential gearset.

Hopefully you'll find the problem is a loose pinion shaft retaining nut or some other simple issue and not the gear teeth face wear from lack of proper lubricant.