They'll tell you it's perfectly OK, just as it used to be posted on their website under FAQ.quote:
Originally posted by Greaser:
I E mailed Mobil with reguards to using 4 litres of 10W-30 SS and 1.7 liters of 15W-50 SS (Jeep 4.0L takes this amount)in a summer time condition...I post their answer when I get one.
5w30 will flow better than 10w30, but mainly in cold weather. When it's hot outside, both will flow virtually the same. So for hot California you simply have no real need for 5w30 that's all. Also, with a pushrod engine like you've got, faster oil flow on cold startup isn't quite as critical as it would be in an overhead cam engine.quote:
Originally posted by z284life:
The confusion of some guys saying 5w30 is better since it flows better and is recommended for new cars/owners manual. Then the other half say 10w30 protects better! I feel both are acceptable to use it warm climates like california, but the arguing I see goes back and forth on what guys use.