Gear Oil Shelf Life?

[nascarnation]

The 47 year old gear oil in my 67 Camaro was working just fine when I did a restoration.
This car came with a very complete life time set of service records and I have 99% confidence it had never been replaced from factory fill. There was no obvious leakage at the gasket or seals.

I replaced the lube because I had drained it out as part of pulling the diff cover to paint it.

 

[zeng]

Originally Posted By: nascarnation
The 47 year old gear oil in my 67 Camaro was working just fine when I did a restoration.
This car came with a very complete life time set of service records and I have 99% confidence it had never been replaced from factory fill. There was no obvious leakage at the gasket or seals.

I replaced the lube because I had drained it out as part of pulling the diff cover to paint it.

Wow ..... 47 years old gear oil.
It has to be a dino ....... any clue as to FF viscosity grade ?

 

[nascarnation]

Whatever GM used as factory fill in 67.
The manual recommends MIL-L-2105B SAE 80 for all temps.

 

[jayg]

The oil is fine. Use it.

All oil companies cover themselves because they don't know the conditions it was stored in. If it was stored in 120F humid garage for many years then maybe it degraded and they aren't chancing recommending that though it's likely perfectly fine. They make money selling new oil and aren't going to risk a lawsuit recommending something they don't have all the details on. Because they told you not to use it doesn't mean their product is bad, it means they have a legal team and attorneys on retainer they don't want to have to use.

Any and all oil, if stored in a cool dark place has a shelf life of longer than you or I will ever see. Shake it up, leave it in the sunlight to warm it up before adding it if you choose but it's fine.

I'm using 44 year old oil on it's 4th year of low mileage OCI with no issues. I'm doing it for fun and because I can. Your 5 year old Amsoil is fine.