topping up. mixing semi with fully synth - MB
My Toyota needs a little oil and coolant - it has semi synthetic oil. My question is can I put 100% synthetic oil in (300ml) to top it up?
Also can I put in another make of coolant in or should I use Toyota\'s own stuff - again it is a small amount but getting the dealer is a bit of a trip...

topping up. mixing semi with fully synth - fossyant
Do not mix semi and synthetic oils - try to top up with the same oil. If you intend using synthetic in the future, I would recommend using a flushing oil first then completely renew. Don't mix both types, this can damage the oil already in.

As for mixing coolant - make sure you replace with the same type - there are about two main types, the most common is ethlyne glycol (or however it's spelt) - check your handbook, then get the same specification.
topping up. mixing semi with fully synth - SjB {P}
On the subject of oil, I tend to disagree.

In the case of my Volvo as an example, it was explained to me that so long as the grade and API certification is correct, and the change interval is not exceeded, no worries. As a case in point, I ran a previous car that had been quite highly tuned for eight years, filling with fully synthetic at oil change time, but topping up with semi-synthetic if I had no choice. Until a piston ring broke (because as I then found out the piston was fitted back to front at manufacture in terms of the thrust face!), the engine was happy as Larry.

With respect to flushing oil, Volvo stress "don't use one", as to do so often causes more damage than good.
topping up. mixing semi with fully synth - Civic8
Think you will find don`t mix fully synthetic with mineral.should be ok with semi.
topping up. mixing semi with fully synth - Sooty Tailpipes
While it's not 'best practice' to mix and different oils or other fluids, there should be no harm what so ever in mixing any which are approved for the engine and of the same spec, and even no likely harm if the spec is slightly different, ie SJ. 5w40 + SJ 10w40 should be fine.
topping up. mixing semi with fully synth - fossyant
Semi synthetic is mineral based.
Small quantities should be OK, but best mixing oils of same types. Semi and mineral OK, but synthetic and mineral isn't recommended - not saying you can't do it though !! I wouldn't use flushing oil (as an additive to oil - i.e. the small can) as a regular thing, and have only used it once or twice. Once when I changed from semi to fully synthetic, another time when servicing an old car ! Haven't used it in our current modern cars !!
topping up. mixing semi with fully synth - MB
Thanks to all for answers - it will only be in a short while as it's change time soon...
topping up. mixing semi with fully synth - RichardW
The biggest question here is why does the coolant need topping up? Find out before something lets go big time and lands you with a big bill!

No worries on the oil front as long as the top up oil meets the required spec for the engine.


Is it illogical? It must be Citroen....

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