Does oil go bad in the bottle?

[goldylocks303]

I was changing the oil on my bike the other day.  It never takes exactly X quarts (no one's does) so you have a bit left for topping off later that sits in your garage somewhere in it's original bottle.  Normally I ride enough so when the next oil change rolls around the leftover is the first to get used.  Last year was a slow year for me and I had a half quart that had been sitting about 9-10 months.  This is all synthetic, by the way.  When I opened the bottle to dump it in, it had a funny smell.  Not as burnt as the smell of the used oil coming out of the bike.  But it was reminiscent of used oil.  I opened a new bottle for comparison and the two smelled nothing alike.  

So: Does synthetic oil go bad just sitting?  What would you expect the shelf life to be?

eD

P.S.  I don't need the lecture on waiting 10 months to change my oil, already heard it.  

[jschmidt]

No.

[Y.B Slo]

I have never heard of oil going bad just sitting for a few mouths. But I'm certainly no expert on oil. Did you say 10 months without an oil change?  

[Boxerdawg]

Not going to go bad in the bottle whether 10 months or......... 10 years.  Uhh, I guess you are keeping the cap on it?  Oil whether Dino or synthetic is by is nature quite inert. Air exposure simply won't cause oxidation.  Liquid water could cause the oil to get funky  hence my suggestion about keeping the cap on.

[jschmidt]

Uhh, I guess you are keeping the cap on it?  

I too was assuming...

[bizarro]

Don't know about oil but I certainly do from time to time......

[evilmedic13]

What was the expiration date on the bottle?

[goldylocks303]

I looked for some warning about going bad and didn't see one but I didn't really look for an expiration date.  Yes the cap was on and it was tight and the oil was actually stored indoors the entire time.  

My buddy just won 12 quarts of racing quality synthetic so I'll probably just toss this half quart that smells funky.  Why use a questionable old when you have a better quality new?

eD

[veefer800canuck]

This should be a good general indication:

Question:  
Shelf Life of Unopened Mobil 1 Quarts
Does Mobil 1 synthetic motor oil (in an unopened quart) have any sort of shelf life, like conventional motor oil?  
-- John Lantz, Littleton, CO
 
Answer:  
ExxonMobil recommends a five year maximum shelf-life for engine oils, including Mobil 1.  

[CBRXXBLACKBIRD]

Don't know about oil but I certainly do from time to time......

 

[county]

It is usually not fit to drink after the seal has been broken for over 60 days.

[Snowbird]

I looked for some warning about going bad and didn't see one but I didn't really look for an expiration date. Yes the cap was on and it was tight and the oil was actually stored indoors the entire time.  

My buddy just won 12 quarts of racing quality synthetic so I'll probably just toss this half quart that smells funky.  Why use a questionable old when you have a better quality new?

eD

Re: "but I didn't really look for an expiration date. " Those guys were fukin' with ya.

"I'll probably just toss this half quart that smells funky."  All oil smells funky. Use it in your lawn mower... or at the very least, recycle it.

Oil repuedly may go stale after a long time, but your bike will be replaced several times in the meantime. Oil is millions of years old... a few more years won't hurt.

10 months between changes? I've gone over a year at times. I have one engine that's within factory specs and it's been running over 50 years.

There are more important things to worry about, IMO.

[Baz]

Actually, the oil will not go bad but if left opened it can affect the additives added to the oil if applicable. (Some can evaporate)

But really, it's been in the ground for a few thousand years, you would think it would be ok in a bottle for a year!

[goldylocks303]

Re: "but I didn't really look for an expiration date. " Those guys were fukin' with ya.

"I'll probably just toss this half quart that smells funky."  All oil smells funky. Use it in your lawn mower... or at the very least, recycle it.

I kind of figued it was a joke but I don't know evilmedic at all and didn't want to insult his gear-head-ness in case he was serious.  

It will get recycled.  All of the oil I use smells funky, this one bottle smells completely different, hence the worry.  It's not a big deal, only half a quart.  

eD

[evilmedic13]

I kind of figued it was a joke but I don't know evilmedic at all and didn't want to insult his gear-head-ness in case he was serious.  

It will get recycled.  All of the oil I use smells funky, this one bottle smells completely different, hence the worry.  It's not a big deal, only half a quart.  

eD

My bad,there was supposed to be a smilie there to indicate I was being facetious, sorry.   Don't worry 'bout insulting me, I insult myself wayy better than anyone. The only gear-head-ness I have is the wear pattern on top indicating a need for new hair!

[LENSMAN]

over a long period of time, bacteria will break it down, but we're talking at least nine months- heat plays a factor.

[jschmidt]

over a long period of time, bacteria will break it down, but we're talking at least nine months- heat plays a factor.

Where'd you get that factoid?

[MOVFR]

Where'd you get that factoid?

Fortune cookie

[LENSMAN]

Fortune cookie

I used to work in the engine oil lab for a major chemical company.  
Most oils have some sort of biocide in them, or used to have it. It's been a while. Try it some time with used oil, see if I'm right.