Royal Purple

[LS1 TA]

Using "miles per tank" is not very accurate. You need to keep accurate records of the miles driven and the exact number of gallons it took to fill the tank. Miles per gallon is what you need to evaluate the effects of the change.

The the tanks hold 16.7 gallons, I believe, and I always fill it up at about the same spot with about 13.2 gallons going into the tank before the pump cuts itself off. I just assumed dividing the miles on that tank by the gallons I put in would give me my miles per gallon.

[SteveH95Formula]

The the tanks hold 16.7 gallons, I believe, and I always fill it up at about the same spot with about 13.2 gallons going into the tank before the pump cuts itself off. I just assumed dividing the miles on that tank by the gallons I put in would give me my miles per gallon.

If you look at the owners manual of the 3rd and 4th Gen. Camaro/Firebird the tanks hold aprx. 15.5 Gallons just for clearification.

[ryan34]

If you look at the owners manual of the 3rd and 4th Gen. Camaro/Firebird the tanks hold aprx. 15.5 Gallons just for clearification.

Thats actually just for early 4th generations. I'm pretty sure they upped the size of the tank, although i don't know which year.

[LS1 TA]

If you look at the owners manual of the 3rd and 4th Gen. Camaro/Firebird the tanks hold aprx. 15.5 Gallons just for clearification.

1999 Pontiac Firebird: Firebird's changes for '99 included larger fuel tanks (from 15.5 to 16.8 gallons), available traction control for V6 models, and a limited-edition 30th Anniversary package for coupes and convertibles.

Just for clearification

[sneitzel]

T... before the pump cuts itself off...

While that will give you a pretty close approximation of a "full" tank, realize that the backflow/back pressure device on each pump is going to react differently. Not only is each nozzle going to react differently, the reaction on an individual nozzle can vary from day to day depending on the ambient temperature and the number of other people filling up at the same time (which will more than likely change the flow rate of fuel out the end of the nozzle) among other factors.

Granted, these differences are not huge but they could account for a couple of tenths of a gal. difference in your Full tank.

Plus, I'm assuming you never top-off your tank? I usually do, and depending on the station/pump/conditions I can fit anywhere from .25 to 1.5 gal extra in my tank after it has auto shut off.

Scott

[LS1 TA]

While that will give you a pretty close approximation of a "full" tank, realize that the backflow/back pressure device on each pump is going to react differently. Not only is each nozzle going to react differently, the reaction on an individual nozzle can vary from day to day depending on the ambient temperature and the number of other people filling up at the same time (which will more than likely change the flow rate of fuel out the end of the nozzle) among other factors.

Granted, these differences are not huge but they could account for a couple of tenths of a gal. difference in your Full tank.

Plus, I'm assuming you never top-off your tank? I usually do, and depending on the station/pump/conditions I can fit anywhere from .25 to 1.5 gal extra in my tank after it has auto shut off.

Scott

Usually I do top it off. In order to try and keep things as constant as possible, I used the same pumps at the same station for about 5 tanks of gas. I just let it run each time until the pump shuts itself off.

[Joe 1320]

You guys need to calculate average mileage. Fill up to the top of the tank. reset the trip meter. Drive until whenever you feel like doing a refill. Record the mileage and start over. Do this 10 times, total up the gallons used and the miles traveled. You'll be close to your acual average mileage. That's the only way to get a good reading.