[Primus]

Well, it's that time and miles. My truck's second oil change is coming up but I am a little concerned because of the first week I owned it: had to make a few trips to the dealer for some post-buy stuff and during that time I got the worst miles to the tank: 163.:rant: With that in mind, I also changed the oil the first time to Valvoline SynPower full synthetic 10w-30 because, if my gas was that bad when I first bought my truck, then the oil the previous owner put in might have been some cheap ass shit they call oil that barely meets the minimum oil quality standards for conventional. My concern is that my engine could be sludged up now from the cleaning additives of the full synthetic, hence the reason I am going to the dealer for my oil change.

 

[Mystake]

i thought synthetic was not only better, it actually helped clean sludge from other oil changes?

 

[Jecht]

How many miles on truck when you got it? Also bad gas mileage isn't a sign of bad oil. It can be many different factors. Syn does have cleaning agents but so mild that it won't break down all the sludge. You can't assume you have sludge unless you verify it. I take it you have the 4.7? Only way is to pull the valve cover. I can suggest a product called auto rx. It can break down sludge and not clog your oil pump screen. Lots of people swear by this product. I used it in my wifes Malibu and cleaned up the valve area quite good.



But first verify why you are getting bad gas mileage. Second ck under your valve cover for sludge.

 

[6shooter]

for the mileage, i would try the basics, like clean the TB, replace the spark plugs, maybe air filter if the dealership didnt do it already. and you need to give us a number for mpg or how many gallons it took to fill it back up, not just 163 miles. that number alone doesnt tell us anything.

as for the oil, jecht is right. unless your engine has 200k on it and its completely packed with sludge, its not going to greatly affect your fuel mileage. fuel mileage is dependent on the fuel system condition itself, how you drive, weather conditions, etc. not what kind of oil is in your truck.

 

[Primus]

Yeah, I have the 4.7 and that fill up that week was between 17-19 gallons, do the math then. As for my concern, dealer tech didn't see anything that was out of the ordinary so maybe I was being anal. :funny:
As for the gas mileage after, I have been getting up 17 mpg when the weather was warmer, now it's been around 12-14 mpg but there is a lot idling in there because the temperatures were below freezing and lower at times during the nights a few weeks ago.
Right now, this tank may not be very accurate due to throttle body replacement(one of Dwight's), which means the values had to be relearned, and a small crisis: both o-rings on the IAC were torn when I was removing it from the TB and the ones I got from O'Reilly's were WAY too big and the IAC is not properly seated. So, I won't know how this tank will be until I have to fill up again.

 

[Jecht]

Yeah, I have the 4.7 and that fill up that week was between 17-19 gallons, do the math then. As for my concern, dealer tech didn't see anything that was out of the ordinary so maybe I was being anal. :funny:
As for the gas mileage after, I have been getting up 17 mpg when the weather was warmer, now it's been around 12-14 mpg but there is a lot idling in there because the temperatures were below freezing and lower at times during the nights a few weeks ago.
Right now, this tank may not be very accurate due to throttle body replacement(one of Dwight's), which means the values had to be relearned, and a small crisis: both o-rings on the IAC were torn when I was removing it from the TB and the ones I got from O'Reilly's were WAY too big and the IAC is not properly seated. So, I won't know how this tank will be until I have to fill up again.

That's normal mpg what's I get in mine. Winter gas will kill mpg averages. Mix is 14 to 15 best.