I switch to the Vavoline High mileage oil my last oil change about 500 miles ago and notice I am getting a little less gas per MPG. It's about 10 less per tankfull. First I thought it may had just been the way I drove, but after the second fill-up, it was the same thing. Upon farther investigating, I looked on the back of the 10w-30 Vavoilne High mileage oil qt and notice it DID NOT say "energy conserving" like on a regualr 10w-30 oil qt. I checked out Pennzoil, Quaker State, and Castrol's 10w-30 high mileage oil and neither of their said energy conserving either.

Looking at Pennzoil, Vavoline, QS, Castrol's 10w-30 regualr convetional motor oil and it all said "Energy conserving" but none of their high mileage oil said energy conserving. It's not a of gas being wasted or anything but I was just wondering did anyone notice the small decrease in gas mileage while using the high mileage oil.

 

you know, I also did notice a slight decrease in gas mileage after switching to high mileage oil. I switched from a synthetic though so I just thought I would expect such a change because the high mileage oil is conventional

 

that high mileage oil doesnt do **** for you man. just stick to regualr valvoline oil.

 

Pretty much.

If the motor was healthy before it, it's going to be just fine with whatever you've been feeding it.

10 miles per tank, that's not a large enough difference to set off any alarms about a decrease in gas mileage. Too many factors involved.

 

yup... changin oils wont make you lose that much mileage. slap some chemtool injector cleaner or some other brand and see if it makes a difference. you might just have clogged injectors.