Filling up with the good stuff

[Frodo]

Originally Posted by keysguy

If I'm only putting a couple of gallons in I'm really screwing myself.

Really?? If it's due to financial constraints that you're only putting a couple of gallons in, you're definitely driving the wrong car!

[leftfield6]

According to various sources (google is your friend), it's less than 1/3 gallon in almost all cases. This is regulated state by state, so check with your state's Dept of Weights and Measures. They are the people who inspect and certify gas station equipment to make sure the consumer is getting what they pay for.

If you are filling up your tank, it has around a 17 gallons of capacity. 1/3 gallon of the wrong octane rating is going to be so diluted into the right stuff as to be a complete non-issue. It would make up less than 5% of your full tank of gas.

Even if you are only putting in 3 gallons (and why the hell does anyone do that?) remember its still going to be diluted into the same approximately 17 gallons as well. Assuming that what you had in the tank already was the right stuff.

If you are cruising around on "E" then buying 3 gallons, then back to E, then 3 gallons, and on and on, then yes, you are going to have a higher percentage of "bad gas". But if this is what you're doing, you don't need a Boxster, you need a Honda Civic.

really, the only people who should even care about this are motorcycle riders who have a motorcycle that needs 93. My bike does, and I have a 3.8 gallon tank, so that 1/3 gallon is a bigger deal to me. But honestly, I've never had a fuel related issue with the bike, so I'm not worried about it at all.

[Perfectlap]

^ I never run with more than half a tank. I've convinced myself that less weight over the life of the car is easier on the consumables. And now you tell me I'm losing a dollar!!!

[jdlmodelt]

Originally Posted by Perfectlap

^ I never run with more than half a tank. I've convinced myself that less weight over the life of the car is easier on the consumables. And now you tell me I'm losing a dollar!!!

i keep mine topped off. I don't go below a quarter tank and ussually top off at 1/2 tank. It's best on your fuel pump to keep the tank topped off. It will permit the fuel pump to overheat and prematurely fail if you run on the bottom half consistently.

[Giller]

Originally Posted by Frodo

Really?? If it's due to financial constraints that you're only putting a couple of gallons in, you're definitely driving the wrong car!

Putting a couple gallons into the car over and over is silly - but there is something to be said about keeping the tank on the lower end (well, not full anyways). Gas can add a lot of weight to the car. I know people who swear by only keeping the tank half full and they see a 'big' improvement in their MPGs. They also feel the car performs better (it's lighter). Plus they say it keeps the gas fresher, especially in a car that sits for extended periods.

Not sure how accurate it is, but the belief is out there.

[JayG]

Originally Posted by Perfectlap

^ I never run with more than half a tank. I've convinced myself that less weight over the life of the car is easier on the consumables. And now you tell me I'm losing a dollar!!!

Originally Posted by Giller

Putting a couple gallons into the car over and over is silly - but there is something to be said about keeping the tank on the lower end (well, not full anyways). Gas can add a lot of weight to the car. I know people who swear by only keeping the tank half full and they see a 'big' improvement in their MPGs. They also feel the car performs better (it's lighter). Plus they say it keeps the gas fresher, especially in a car that sits for extended periods.

Not sure how accurate it is, but the belief is out there.

WTF ????

half a tank to save weight for better MPG? You must be joking!!!
Gas weight just over 6lbs per gallon so 8 gallons is approx 48 lbs

I know for racing, they watch every pound, buy that is to squeeze out every ounce of performance and sometimes has to do with rules as well.

As far as effecting MPG, sure, it will have some effect, but probably measures in 10ths at best. If you are so worried about weight, did you take out your spare and toolkit? Running lightweight wheels? No extra crap in the car?

Big improvement in MPG, no way!!
Big improvement in performance? get driving instruction, its unlikely you drive anywhere near the top of the performance envelope in your Boxster. 50 lbs ain't gonna make a difference