Can motor oil go off?

[trigger]

My old chap has 3 or 4 5 litre cans of Castrol GTX on the shelf in his shed, He's had them at least 20 years and they are still sealed and in plastic cans.I need to change the oil in my 02 at some point soon and was wondering if it's still o.k to use, I'm pretty sure it would be as I'm sure oil doesn't go off, does it?.Can't remember what the grade is now, It's not 20/50 but something like 10/40, The haynes maunal recommends Castrol GTX.Bit of a daft question i know but just checking.

[KruJoe]

Surely if it deteriorated at all, there would be a best before date on the cans somewhere?

[pogweasel]

If it's in placca, which takes 8.3 million years to degrade, surely it must be OK. I say open one up and pour some out. If it looks like oil then go with it. If it looks like cheese, coal or goats faeces, then don't.

[trigger]

This what i was thinking, Oil's millions of years old so 20 more years should hurt it do much, Dad said i was a twat for even thinking that oil goes of but i wasn't that sure.

[Station]

There's nothing in oil to emulsify, it's just oil. ;)I heard petrol can go off, is this true?

[Volksy]

I heard petrol can go off, is this true?

It does. As its a 'spirit' it evaporates, leaving a sticky varnish behind. Which clogs up fuel pumps, carbs, injection systems. Hence when buying a car thats been laid up for a while, its best to clean the fuel system out before trying to get it going.

[Timewaster]

I've worked in places that have had obscure grades of oil for sale on the shelf for 20 years!If it is in a tin then its at least 15 years old, I seem to remember they changed to plastic in the early 90's. If its a sealed container it will be fine. GTX has changed grades a few times over the years.I think it was 20w/50 to begin with, then 15w/50 and later 15w/40.Now it is available in all sorts of grades specifically for petrols and diesels.

[trigger]

I'm sure it's 15w/50 now you say it, Should of checked yesterday whist i was round his, it's in a white plastic can under all the dust.

[Andrew353w]

This is slightly (=quite a bit!) off topic, but why do mineral water bottles, containing a product that has been filtered through the ground for millions of years, apparently without suffering any ill effects, have a "best before" date? I can't see why 6 months either way over and above 2 million years would make any difference! Perhaps this ought to go on the 'Grumpy Old Men" thread!

[Timewaster]

apparently mould can grow in the bottles. nice!