Can oil viscosities be mixed?

[mikes_box]

just wondering if i can mix oil viscosities... when i had my car ppi and they did a oil filter analysis they topped it off with a mixture of 5w30 and 15w50 so i assumed they must have made a mistake and accidentally hit the button wrong so i went ahead and did an oil change using 5w30... i don't want to waste the oil in the car as its only been a few hundred miles and was wondering if i can drain out half of the oil and just mix it with 15w50... any help would be good... thanks.

[Sputter]

The recommended fill is mobil 1 0w-40 or even a 5w-40

Since you're asking, dump the oil and do a proper fill. (filter and oil). Oil is cheaper than a engine.

Mind me asking where you got your information? Why 5w-30?

just wondering if i can mix oil viscosities... when i had my car ppi and they did a oil filter analysis they topped it off with a mixture of 5w30 and 15w50 so i assumed they must have made a mistake and accidentally hit the button wrong so i went ahead and did an oil change using 5w30... i don't want to waste the oil in the car as its only been a few hundred miles and was wondering if i can drain out half of the oil and just mix it with 15w50... any help would be good... thanks.

[70Sixter]

I have read a lot about oil lately and still do not know if the viscosities are linear when mixed. I saw on one site (LN Engineering maybe) that they mixed 0W-40 and 10W-40 and calculated that they got 5W-40.

[geoff]

I had bookmarked the following threads on the Bob Is The Oil Guy web site that talk about mixing oils and calculating the resulting viscosity a while ago. YMMV

http://www.bobistheoilguy.com/forums/ubbth...p;Number=826268

http://www.bobistheoilguy.com/forums/ubbth...p;Number=734304

http://www.bobistheoilguy.com/forums/ubbth...p;Number=175127