Oil change using left over oil.

[Skylarking]

One oil manufacturers help line I called stated to me that oil has a shelf life of 5 years. When pushed as to why, he told me it was related to issues with additives but as long as it doesn't look like the oil has stratified or has sediment on the bottom, it should still be OK to use.

So, using the left over portion of an old bottle of oil shouldn't cause any issues, especially if your sensible and ensure the above and ensure the new oil bottle is from the same brand and grade as your old oil. About the only time one should be cautious is if you start mixing different brands, grades and especially different oil base stock.

I'd especially avoid mixing different oil base stocks like caster oil with synthetic oil as I've read there are issues with additive incompatibilities. In such cases you're into more complex territory and playing a chemical engineers game and I simply don't know enough to determine what the outcome would be. .

The only time i had any sort of issue was when I mixed two different left over oils (i think they were "Castrol Formula R Synthetic" and some much cheaper oil) and i got some waxing under the oil cap. Didn't wait for a problems to occur so I flushed the hot engine oil and filled up with new oil from one single bottle. That was a few decades ago and I've never had any issues since as i stuck to mixing same with same. Avoid mixing stuff from a different decade and especially different millenniums

 

[07GTS]

i always keep the left over oil as with an 8.3L fill i have to get 2x 5L or 6L so always have few litres left over, never had any issues and bottom end bearings look fine after years of it even under boost

 

[greenacc]

It's ridiculous to think oil goes off in six months or a year. It lasts for a year being pumped around a hot engine full of combustion products. It ain't gonna go bad any time soon sitting nice and cool on the shelf. It's like saying if you fill up at a different petrol station and mix shell with BP your engine will seize.

 

[Mayuri Krab]

It's ridiculous to think oil goes off in six months or a year. it lasts for a year being pumped around a hot engine full of combustion products.

Or 2 years according to BMW...

 

[07GTS]

Or 2 years according to BMW...

or Mercedes bens 30k service interval

 

[Terry57]

Thanks for the replies, very informative and helpful forum.
Ta.

 

[Lex]

Thanks for the replies, very informative and helpful forum.
Ta.

How is the tranny? Still good?

Sorry wrong thread.