Does Oil Expire?

[Champ]

At 12 hrs I used Aeroshell 100 Mineral Oil in the RV that I had left over from a TOH on the Champ 25 years ago. I figured a few more years on dead dinosaurs would have no significance. When I got the case I ordered this week it had a "Use By July 2020" date on it. Does oil expire? I've put a couple hours on the old oil. Will I fall out of the sky? Hurt my engine? Pardon me if this has been covered before - I confess I didn't check.

[Mel]

For all practical purposes, NO! (If it has remained in factory sealed bottles)

The oil manufacturers place, I believe, a 5 year expiration date as a CYA.

[Robin8er]

I know that on the fancy multi weight oils the friction modifiers can separate, but it takes years of sitting on a shelf to do that.

[Champ]

Thanks guys. This was single weight mineral oil from the original sealed containers. 7 qts old, 1 qt new. Thought the new might have been a little lighter in colour but I couldn't swear to that. I'll fly on with the old stuff to the next change at 25 hr. Still monitoring it but it looks like the engine is already broken in. CHTs are good and oil consumption is low & stabilized.