High milage oil mix?

[raskm]

You think 1qt mixed with 4 qts is ok....I got a case of castrol 10w 30 HM and accidently 1qt 10w 40 HM...to lazy to take it back or should I?

 

[seotaji]

It really doesn't make a difference.

 

[TallPaul]

The overall mix would still be a 10w30, just a slightly thicker 10w30.