1955 Buick Rear End Gear Lube type & Weight?????

[FireballV8]

I was wondering what gear oil to use. I was reading that there are GL-5 & GL-4 types and GL-5 attackes brass and copper.

So what brand and weight should I use in my 55 Century?

thx

[old-tank]

You read too much and worry too much . Anyhow you got me curious and I went to the shop to see what I have been using. The bottle of Pennziol 85w140 is rated GL-3, GL-4, GL-5. No failures in any of my 3 cars driven 5k-40k. This article seems to make the most sense. I have not inspected any of the brass washers, but did not see any metal particles a few months ago when I removed the differential cover to replace the gasket. This probably another 'non issue' like zince in motor oil.

Willie

[NTX5467]

As noted, there are several "GL" specs for gear lube with respect to the types of metals it will be in contact with in the transmission or axle. Typically, where the GL spec is more critical is in manual transmissions which have brass synchronizer rings and such. Synthetic gear lubes must meet the same GL spec as the normal gear lubes too . . . for the same reasons the normal lubes do. Still, if the vehicle/component manufacturer has a "GL" and viscosity lube spec, it needs to be followed.

Enjoy!

NTX5467

[FireballV8]

Thanks Guys

So Willie you use the heavier gear oil? The book says SAE 90, so is it okay to go to 140 weight?

I have changed my wheel seals again as the gear oil went through them and soaked the rear brakes. I had used old leather seals and I think they were too old yet new. I replaced them this time with new rubber seals. Funny thing is their was no dynaflow fluid in the rear and the level was lower than the bottom of the filler hole. So I am not sure why it went through the seals. I also checked the vent and it is working as well.

Also where do you get a gasket for the rear end cover? I bought one from BEST Gaskets for my other 55 and it leaked, their gasket was very thin paper material. So I made one out of cork. Any ideas??

Thanks

[old-tank]

I use the 85w140...kinda like the 20w50 I use in the engine instead of 30. It apparently works well with no leaks. When I broke the axel on the way back from Batavia the shop that did the work used 75w90 and that worked and maybe even gave better gas mileage, but it seeped everywhere including around the pinion locking bolts. They also could not find a gasket or wanted to make one for the rear cover so they globbed on a bunch of RTV that leaked. I use Felpro 3019, Cork 1/8 12X36 Sheet to make my gaskets for the rear cover.

Willie