Ok so I was setting out on a drive when I made a routine check of my oil. Low again (not unusual since I've done a bit of hard driving since my last change).

Go to my stash of Mobil One in the Garage - one bottle left - but I mistakenly bought the 15w 50 oil.

Was worried about adding this so I stopped along the way and put in more of the same weight usually run

Question: What would this have done? Anything? I'm guessing couldnt be that bad - 1 quart.

Also - the 15w 50 does say high performance and am guessing a higher viscousity is not all bad as the weather gets hotter up here.

Thoughts?

 

15w50 is a bit thick. I'd do another change.

 

Multigrade oils of any particular type will be more or less completely miscible with one another. If you added 1 qt of 15W50 to say, 4 qts of 10W30 that would already be in your crankcase, you would simply be averaging out your oil and numbers.
ie: you'd have about the equivalent of 11W34 oil. No big deal.
It's not like you'd have "pockets" of 15W50 oil pumping throughout your engine.

 

[QUOTE]Originally posted by xviper
[B]Multigrade oils of any particular type will be more or less completely miscible with one another.