I was going based on what members have been reporting. For highway 27-30mpg is not uncommon. 24 mpg is the MAX my car will get with granny style freeway driving so I figured something was up.

 

I have the A/T as well. And the highest MPG I have ever gotten was 27. And that was running the tank till I was damn near afraid it was going to go dry on me. I have a mixed driving between highway, city, and back country roads every day to work and I usually average 21-23 mpg. Not as good as some numbers I have seen on here but I guess its not bad since I have a hard time keeping my foot out of it in the mornings behind all the slow drivers... -_- lol

 

Well I just got 24mpg for 75% highway use 25% city use and actually not holding back sometimes to keep RPMs low. Maybe I could squeeze 2-3 more MPG's if I put a hold on hearing the car at 5k RPMSs lol

 

For your idling issue, clean your throttle body. That fixed it for me. My car was idling like crazy. For example when I was driving and put it in neutral, my rpm's would drop near 100 and my lights would dim and my car would seem like it was about to die.

 

Fixed the issue with what I though it was in the first place.
Dealership used cheap, thin oil. Replaced with 5/30 synthetic and now getting 27mpg. If I use stock rim/tire spec I could probably bring it up to around 30.

Thanks for the help

 

Shouldn't have made a difference as the 5w means that's the winter viscosity at 0c and in Cali it hasnt got that cold here yet.. Did you change the brand? Or maybe you were just over due on a oil change

 

The thinner the oil, the better MPG you should get. Just look at any hyper-miling forum. Those guys run the lowest viscosity oil they can to increase mileage. I can see if they put a 20W-50 oil in your car it mike lower your mpg, but my guess is the dealership used a 5w-30 or 10w-30 since it is summer.

 

yea i noticed quite a difference too when my mech put in 10w30 oil in mine. my mpg went down a bit. i'm going to try to put in 5w30 when i'm due and i'll let you guys know how much of a difference it makes. or maybe you could try diagnosing your car if it's due for a tune-up?

hope this helps bro!

 

Ok you guys obviously don't understand but ok... 5w30 and 10w30 would be the same in summer temp only difference is in winter the viscosity changes That's why it's called a multiviscosity oil The w doesn't stand for weight it stands for winter aka 5 weight in winter 30 in summer

 

This.

 

Found this on another site where people where asking about ENGINE OIL. Thought I would post it up here for reference:

"The Society of Automotive Engineers (SAE) established a numerical code system for grading motor oils according to their kinematic viscosity.

The viscosity of single-grade oil derived from petroleum unimproved with additives changes considerably with temperature. As the temperature increases, the viscosity of the oil decreases in a relatively predictable manner. On single-grade oils, viscosity testing can be done at a cold, winter (W) temperature to grade an oil as SAE number 0W, 5W, 10W, 15W, 20W, or 25W.

The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold ambient temperatures in the winter before the vehicle is started up to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a low viscosity at the engine's operating temperature. The difference in viscosities for any single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers, or VIs are added to the oil. These additives make the oil a multi-grade motor oil.

10W-30 designates a common multi-grade oil. Historically, the first number associated with the W (again 'W' is for Winter, not Weight) is not rated at any single temperature. The "10W" means that this oil can be pumped by your engine as well as a single-grade SAE 10 oil can be pumped. The second number, 30, means that the viscosity of this multi-grade oil at 100°C (212°F) operating temperature corresponds to the viscosity of a single-grade 30 oil at same temperature."

Cheers!

 

So what your trying to say is the five mins the engine pumps the 5w when cold gives a 3-4 mpg boost doesn't seem likely but hey I'll try it too and see what happens

 

i live in detroit and based on the chart on the back of the oil bottles 5w20 is great for our extremes in temps...so personally i just run mobil1 5w20 everytime i do a oilchange(since i get it free at work..top secret way, shh!..) and change my oil and filter every ~4kmi...

before i started using full synthetic i was getting about the same mileage i got after i switched to mobil1, and i was using semi-syn..its estimated u get about 10% mileage difference from conventional to full synthetic(IIRC....)...and honestly i never saw a noticeable difference...but i still use the syn, because i get it free....otherwise i have to pay for semi-syn 5w20...

ps sometimes i run castrol instead of mobil and have e3 spark plugs...still no difference...w/ stock wheels and stock size tires and SRI...changed the timing belt w/ pulleys also the t-stat and new coolant and cleaned the maf and tbody(i think last year..or the one b4...)...all got me basically the same mpg....(then again i can't stop flooring it..so that may have sumn to do w/ it)..

the only time i ever had a noticeable gain in mpg, i got ~33mpg...i was stuck in a snow storm driving from atlantic city, nj to detroit, mi,all the way thru nj, i drove ~25mph on cruise control, in 4th gear on the freeway, in ~4in snow, w/ my fiancee(at the time, now wife) in the pass seat, a trunk full of stuff and a full tank of gas(all ~13 gallons)...

in conclusion...dont floor it, keep the rpms low and constant...ull get better mileage

 

my A/T gets about 215-230 per tank and my M/T gets 205-220 per tank.... sounds like I need to do some basic tuneup maitenance and that should increase my mpg almost 5 mpg

 

^^ you want to sell that underdrive pulley?