[jblackburn]

Should answer your question:

Ask Mobil 1 Archive - Shelf Life

It's still good - but is it a good oil for this motor to begin with (synthetic 5W-30)?

 

[jblackburn]

IIRC some of that stuff was more like 50 years old. There were no signs of age related deterioration.

My dad had some old Quaker State in an unopened can we found in the back of the garage when they were moving. No telling how old it was. Looked just fine...used it in the lawnmower, but wouldn't put it in my car

But yeah, I'm sure it has a shelf life of >5 years - I see no reason for it to "go bad" in an unopened bottle.

 

[jblackburn]

Been using synthetics in my air cooled back breaking toys as I call them for years. If anything requires synthetics, its an air cooled engine.

They last years longer.

Ha, running a John Deere from 1990 - still remember buying it; dad replaced his with a self-propelled Honda. Deere smokes a bit, but couldn't complain about it otherwise - 21 years for a piece of yard equipment is fantastic in my book - it usually just got whatever conventional oil was on the shelf in the garage.

Ha, but will never buy another modern B&S after having the OHV version in a pressure washer that the valvetrain pretty much exploded on after 10 years. Darn outsourcing is to blame for this...