General LSX Automobile Discussion - oil change gas mileage?

anyone else notice their gas mileage goes down when they get closer and closer to that 3k mark of their oil change? i just put synthetic in my SS and it's supposed to be good for 5k and i'm only at 3150 and my car's gas mileage went from almost 100 every 1/4 tank to 60-70 every 1/4 tank . . . so instead of 400 miles to a tank i'm gettin 240-280. anyone notice this on their LS1 or is this just normal after 3k on the oil?

TTT anyone?????????

I never noticed personally. I just never really think about fuel economy though. That's strange though, with todays motor oils I'd think they would not break down and cause more friction like that. At least not within an oil change interval. I wonder if Patman could voice an opinion?

htf do you get 400 miles out of one tank?....mine has always been 240-280

I can't speak about the gas mileage on the LS1 cars for oil changes b/c I never pay attention its my weekend cruiser.

With my 2 daily driver trucks the mileage does go down once I hit the 2500 mile mark.

My driving habits vary too much to even attempt to monitor small changes in mileage. It all depends on how much I keep my foot out of it (which is hard to do).

I got this car when it had 10,300 miles on it and I have changed my oil every 5,000 miles and the car has 146,000+ miles on it now...it uses a half quart every 5,000 miles and the fuel economy stays the same all the time ..I get 300 miles to a tank doing combined city/hiway driving back and forth to work each week..never noticed any change in it when it gets close to oil change time...:D

My mileage was getting lower towards the last month or so I had the car out, but I wouldn't blame it just on the fact that it is ready for an oil change. Too many other factors, two of which being that the weather was getting colder here and I had just swapped to an LS6 intake and could not keep my foot out of it.

Would there be a chance that anything else changed? I even think driving it without letting it warm up will use more gas as a safty thing but im not 100% sure about that

I doubt that big of a change has anything to do with your oil needing or not needing to be changed. Usually an oil change will not affect your MPG to the point you will notice a gain or a loss.

only reason i know i get 400 is cause i drive highway and only highway every day 60 miles roundtrip. it's in the 50's when i drive to work so when i start it up i let the car warm up for about 5 minutes . . . i did get a LS6 intake back in august and i'm gettin my tune this friday, i'm now wondering if my a/f ratio is off that much hmmmmmmmm

yep a/f was off and i was runnin hella rich!!!! dyno tune fixed me right up!!!!!! back to excellent mpg again

Some areas have a different mix of gas during the Winter months to help reduce smog. I know Portland up here has a winter gas blend required that has ethanol in it and mileage goes down. Maybe the gas has changed.

i was wondering the same but after the tune i was floorin it alot and i still got 320 miles out of the tank. before the tune after i installed the LS6 intake when i did that my tank would last 265-285 give or take some miles