gear oil vs motor oil

[Chris142]

The Auxillary transmission in my old truck calls for SAE90 GL-1 oil. I couldn't find any so I put in SAE50 engine oil which is very close to the same viscosity.

Now the thing leaks out both ends. It did not leak before I changed the oil.

I dunno I can't explain it either. Can I run GL-5 oil in it? I know that some additives in GL-5 are not good for the soft metals but I don't think this trans has any.

It's an old Spicer Brownie with needle bearings and roller bearings.

 

[Merkava_4]

Peterbilts are little out of my league, but I suspect that something in the 50W oil was not compatible with the seals of your transmission. I think what I'd do is get that motor oil out of there and find the recommended gear oil that is safe for your seals.

BY THE WAY!

For those of you who are thinking I misspelled Peterbilt, here's a link:

Peterbilt Motors

 

[bruce381]

SAE 90 GL-1 is basicly straight mineral oil with a ppd.
a 50 wt PCMO is Fine for a brownie been used since they made dirt.

Any leaks are due to
1 maybe it had not much oil in it and now full it leaks
2 new oil washed out gunk

the oil is not he problem it is compatible to the seals a GL-5 will not be any better IMHO.
try some trany seal swell additive or email me I'll send you some seal swell ester to add.
bruce

 

[Chris142]

Will the seal sweller work on leather seals?

 

[Chris142]

Oh the oil level was fine , infact over filled before I put the 50 wt in it. Now it's at the bottom thread and leaks.

 

[MolaKule]

If it has leather seals, they may have dried and shrunk.

I know of no present chemistry that reconditions leather seals.

 

[bruce381]

""Will the seal sweller work on leather seals?""

No, water maybe LOL
or neatsfoot oil worth a try.

bruce

 

[Chris142]

Well I'm willing to try the GL-5. It's easy to drain and fill. Ya'll think it will hurt anything?

 

[road_rascal]

I thought I read somewhere that the weights of motor oil and gear oil are measured differently- that a GL5 75/90 gear oil has approx the same weight as 10w/30 motor oil. I remember posting a question about this in a scooter board because the owners manual for the Yammy scooter says the tranny takes either 10w/30 motor oil or GL5 gear lube.

 

[Chris142]

You saw it here.

http://www.bobistheoilguy.com/visc.html