Mixing Synthetic Oils

[jwinders]

I have a 2008 Honda Accord four cylinder that is about to get it's first oil change. I bought 5 quarts of Castrol Syntec 5W-20 and after getting home and looking in my manual, the crankcase requires 5.6 quarts. I have 1 quart of Mobil1 5W-20 that is left over from the oil change I did on my wife's civic that also uses 5W-20. My question is can I mix the oils since they are both synthetic and the same weight, just different brands? I really don't want to go back out and buy 1 quart of oil.

[RTexasF]

First off are you positive that it is 5.6 quarts?? From 2003-2007 the K series 2.4l in the Accord took 4.5 (+ or - .1) quarts with a filter change. Perhaps they went with a larger oil pan for 2008?

They will likely mix but there is a small chance the additive packages may clash. Were it mine I would keep it all one brand to be safe.

[tom p.]

JW, I've got the same car. I don't think it holds as much oil as you are quoting.

[jimmie jam]

you might want to question the experts. why not go to both websites and look at the FAQ's. you will most likely find and answer. (i don't think that this much oil would be an issue).

[cajunfirehawk]

And for more on oils, see Bob is the oil guy forums... Bob Is The Oil Guy - Powered by Motor Oil

[BigJimZ28]

I fail to see how it is any different then mixxing
the "new" oil with the old oil residue still in the engine

[jwinders]

Thanks for all of the replies and help. I looked in my paper manual and it said 4.4 quarts while my online manual in the Honda Owner's center said 5.6 quarts, so I called Honda directly and found out that the 5.6 quarts is for a brand new engine that has never had any oil in it, and the 4.4 quarts is what is needed for an oil change. It is amazing to think that when you change your oil, 1.2 quarts or so of old oil stay on your engine parts.

[miahman98]

That 1.2 quarts answers the question about mixing different oils.

[d189379]

You can mix without any issues.