You might want to rethink SAE 140, that's too thick.

Posted by kacarlson On 2010/6/13 13:45:36

I had this nagging question many years ago, as my '37 115C called for an SAE 160 in the diff. Having spent many years in fuels labs for the military & private companies, this bugged me that I couldn't find the specs for this oil. So I called SAE. They put me in touch with Janet Jedlicka, the archivist, and she found and sent me the 1929 specs for SAE 160. SAE 160 back then was a summer lube with a viscosity range of 160-170 SUS (Saybolt universal seconds) at 210 deg F. Comparing that to modern oils, it falls right into the lower range of modern SAE 90 oils. Yes, SAE has changed their Specifications. So I called The Gleason Works and spoke with Herman Stadtfeldt, the vice president for research and development. I'll try to post his letter here, but Gleason made the machines that made the hypoid gears for Packard and I figgered they'd probably know what lube is needed in these gears.

(paraphrasing:)

Dear Mr. Carlson:

Thank you for inquiring about the Packard hypoid gear. In fact, The Gleason Works is a machine tool manufacturer for gear machines. All the different Packard hypoid gear sets were manufactured on Gleason machinery. Gleason employed an army of application engineers who provided the development of the individual gear set with respect to size and ratio as a service to its machine tool customers.

The lubricants were manufactured by Shell and other mineral oil companies but were sold like original equipment under the vehicle manufacturer brand. The optimal oil specification with respect to additives and viscosity were determined by the vehicle manufacturer and mineral oil companies using test rigs where they ran the axle drives for many months. The viscosity was and still is the most important factor. The attention was paid to the right additives. Hypoid sets tend to score because of the sliding velocities. To prevent the scoring, a highly toxic "lead soup, active sulfur" type was used to enhance the scoring properties of mineral oil. Today, the use of these lubricants is prohibited by law.

The interesting thing is, that you can use any of today's off-the -shelf hypoid oils (like Castrol Hypoy C Gear Oil (SAE 80W-90) to replace the axle lubricant in your vintage car and still have a better operating axle than the early oil with the special ingredients. The specification of the average axle lubricant between the thirties and the fifties is SAE 90 (MIL-0-2105).