Toyota Camry 2012: Can I mix fully synthetic and semi synthetic oils?
Asked by R
I have a 2012 Toyota Camry, can I mix fully synthetic and semi synthetic oils when I do my next oil change? Both are Castrol.
Answered by CarsGuide4 Jan 2020
Let me guess, you did an oil change 12 months ago using semi-synthetic oil and then another one six months ago using fully-synthetic. And now, there’s just enough oil left in either container that, if you combined them, you could do the next oil change without buying more oil. Am I close?
Anyway, the short answer is no, you shouldn’t mix two different types or grades of oil. Remember the old Castrol TV ads; Oils aint oils? Well, it should have been: Oils aint just oils. Oil isn’t just refined crude; a modern automotive engine oil is made up of lots of components, collectively referred to as additives. These additives make oil more effective at both high and low temperatures as well as providing extra protection and sometimes even a cleaning function.
Which is great, but the different additives in different oils sometimes don’t get along too well when they’re mixed. Sometimes they can cancel each other out, at which point you’re suddenly using oil that doesn’t protect as well as it should.
Keep the spare oil from each oil change as a top-up (something you probably won’t need in a relatively new Toyota Camry). And if it’s not needed for that, give the poor old lawn-mower an oil change with the left-overs. How long since the mower or brush-cutter got some love?
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