Unopened it should last a very very long time. It's enemy is
oxygen. Most oil companies will tell you five years just to
cover their rear end.
Straight 10w is hard to find now a days, but I've got a bottle
of it that I use to fill oil cans. I've had it for about 40 years.
Still looks and acts like 10w oil when I pump it out of the
oil can. It does have a lid but so its been exposed to the
atmosphere, still it looks OK.
I would look for sediment settling to the bottom a cloudy look
to it or rancid smell before I would not use it in a Stovebolt.
It's my understanding that the additives tend to settle out of
a blended oil. So if it's a straight weight I'd say it good
for your life time.
Jerry should be along in the morning to give us the real skinny.
http://www.pbase.com/dennygraham/image/161854703/largehttp://www.pbase.com/dennygraham/image/161854702/largedg
