I just switched over from Mobil1 10W-30 to German Castrol 0W-30. I have about 3/4 of a quart of Mobil1 that I was previously using to top off the oil level. Should I just give away the Mobil1 at the next auto-x meet to someone that uses it, or would you continie to use it to continue to top off the car? Don't know how good of an idea it is to mix and match oil of different weights/brands (then again I am technically running on an oil mix right now since there is .5qt in the oil cooler that doesn't get removed during the OC).

Whats your $.02?

Thanks,
eb

 

People get scared about mixing petroleum base with synthetic too, when all the end up with is a "blend".
It'll mix.

 

yes you can mix it with no ill effects