For example: if my motor had Titan GT1 5W/30 in it and for top-up I use, let's say Castrol 5W/30 - would this be OK? Just wondering because I have some spare oil of the same grade and don't want to go out and buy more oil unless I really have to.
FWIW, both oils are classed as BMW long life oils.
Thanks.
It depends on what additives are in the individual oils, most oil company experts will tell you not to mix modern oils (they would though).
Yes. That's part of the SAE specification.
--scott
Perfectly OK, I have done that for years. Oil is oil and there is no real difference between Halfords and Honda oil that conforms to the same specification apart from £12/litre.
I'd be worried if oils couldnt be combined since you never completely remove the last lot when you change!
It's OK to mix oils as long as they meet or exceed the manufacturers specifications, usually found in the owners handbook. For example SAE, ACEA, API, etc.
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