BETTER Fuel Mileage for me

[MINIHEMI46]

Hey fellow PT's, I've had my PT GT for almost 2 years now. It's an 03 stone white color and all stock and NO Stage 1. I have been getting in the Ocala Florida area, just driving around and into town and some freeway. My fuel mileage has ALWAYS been around 20 to 21 MPG faithfully. I have used Mobile 1 10/30 since it was new, I've had the turbo replaced at 28,000 miles under warranty from Dealer, (Bearing went bad, had to wait for a week to replace turbo). Still the same mileage, never has changed until NOW. This is what happen and I don't know why or care, I changed oil about a month ago to the NEW Mobile 1 10/30 15,000 mile oil. Bought it at Walmart, 5 Qt's for $23.?. Put the same Fram tough guard oil filter and the same type driving and NOW I'M GETTING ALMOST 25 MPG and it's been 3 tankfuls. Drive about 290 miles on 12 gals of high test fuel. I get the gas at RACETRACK here in town and if you guys really knew the truth about gasolines, it doesn't matter where you get it. Same base high test fuel just different NAME BRAND STATION additives and I'm not going there. But the point is I'm getting almost 25 MPG and the same driving habits, some WOT and spanking a few ricers with coffee can mufflers now and then. Just thought I would let you guys know and I'm criusing better now [?]

[Mean Green]

That's a good thing. Mileage will also increase as the mileage increases. My mpg went up 3 mpg on my '01 when it hit 30k miles. Synthetic oil is a very good thing, too.

[GTBlueRoyaltyPT]

I'm so happy for you! I've recently had the opposite happen. My hot royal blue GT PT has always had the best synthetic oil in him - ran great - got anywhere from 22-23 mpg (winter blend) and even up to 30 mpg one summer driving the freeway (probably way over the speed limit - shhhhhh) through the Mackinac Bridge of Michigan! He averages about 25 mpg. That's always been a funny thing - the faster I go on the freeway - the better the gas milage! It was the same with my previous PT (01 - non GT).

Anyways - now for the sob story. I had my spark plugs changed in December. When I drove it out the gas milage immediately dropped to 16 mpg. I know my baby - and something is obviously wrong. I took it back 3 times, got charged an 80$ diagnostic fee each time and they changed a 10$ part. No change in mpg. I then got it to 17 mpg. BIG WHOOPIE! I decide my life is over as my sexy blue PT is dying on me. How could I ever live without him! I love him!

I decided to change the oil last week since the window sticker said it was time to. I was baffled when I took off the sticker to hand it to my regular oil change guy. The sticker had the mechanics name on it instead of my fantastic oil change place that I've used for 15 years. Revelation! - when they changed my spark plugs, did they change the oil too and put old petro based oil in it? Is this the root of all evils? The oil change place could not confirm that it was petro oil drained out last week, but I have the sticker to prove that the mechanics changed the oil in December.

I have not driven enough to see if the milage changes - but I'll keep you posted. The concern now is I'm told what the mechanics did could have caused engine damage. It's ok to change from petro to synthetic - but not vice versa - from what I'm told. I'm trying to find out! Any ideas on where to go to find out?

Jennifer

[GOATFALLS]

I'm going to try it and see if it works

[pdbrains]

Regular oil will break down quicker under the high heat of the turbo and if you ran it long and hard enough before changing the oil you could have caused some "damage" or excessive wear, but I never heard of damaging an engine from just using regular oil as long as the mileage was not too high before it was changed. How many miles did you run the regular oil before you changed it? As for the bad mileage it's more likely that there is something "wrong" with the spark plugs that were installed or the gap is incorrect.

[MINIHEMI46]

Since I've posted this over a year or so ago I have always gotten 24 to 25 in town stop and go and a few miles highway. At least for me the Mobile 1 15,000 mile oil did work. But in January I traded off the 03 GT 5 speed for a 07 GT convertible autostick with 4500 miles on it. I watched the MPG in the dash and it got about 21 with the same driving and I could live with that. At 5000 miles I changed over to Mobile 1 15,000 and right away I'm getting 23, same driving habits so it's working again. I did notice big time the autostick is a turtle compared to the 5 speed. I use to get 3 gear chirps out of the tires at arounf 55 to 60 mph with the 5 speed and that 100 MPH mark would come on fast. But anyways I couldn't pass on the convertible at the price it was so I hope LONG LIVE THE TURTLE EXPRESS. Maybe stage 1 will help it with warp speed. I just don't want to hear Scotty in the transmission room say...Captain SHE'LL BLOW APART.