Mixing oils

[Frodo]

I believe I know the answer to this...but I'll throw the question out there anyway.

Over time, and the course of oil changes, I've collected a few jugs. I've always liked Castrol, used to use their 10W-40 but can't hardly find it anymore, so I've been using 5W-40. These...



My question, probably obvious: Are there any issues, concerns, drawbacks or compromises associated with mixing these to use in my next (upcoming) oil change?

They're both Castrol synthetic 5W-40 weight oils. What's the difference? What exactly is "European Formula"?

[Starter986]

I've used both... regular Castrol syn and the "European" formula. Me? I wouldn't give a second thought to mixing the two. I can't imagine the specs are so different that the car is going to know you're mixing.

Just like Nancy said, "Just do it".

Oh, wait.

[Gilles]

Originally Posted by Starter986

Just like Nancy said, "Just do it".

Uhh.. do you know Nancy as well..?

[FoFoJoe]

I'm no oil expert but I will echo the other reply, I would have no worries mixing the two.

I'll expand on that by saying I would have no hesitation mixing two oils I would run on their own already. So if you would run either one of those oils anyways, then I say go for it.

[Starter986]

Originally Posted by Gilles

Uhh.. do you know Nancy as well..?

Lol. I didn't 'Just say no'.