I need to add a quart of motor oil and the oil that I used when I did my oil change was a Mobil 1 fully synthetic 5W-30 . I have several cases of 0W-40 Mobil 1 fully synthetic but I ran out of 5W-30. Is it ok to top it off with a 0W-40 Mobil 1 fully synthetic or do I need to buy a 5W-30 Mobil 1 fully synthetic. Thanks!

 

How much oil are you talking about when you say, "top it off"?
IMHO mixing oil weights is something to do only when you are forced- i.e., in the back country where no services are nearby.

 

Thanks for the reply. I need to add 3/4 of a quart.

 

I'm sure you'll be more than fine.That stuff flows like 0 weight when cold but protects like 40 weight when warm. You'll be fine.

 

Thank you for the reply!