gas milage

When I'm in the lawn chair is when my mpg go up.

My bad. Premium has less btu's but burns slower so can go with a higher compression ratio. I specified "branded" gas because as srt20 found out, the Indians, Walmart, etc. use a cheap gas with few additives and don't perform well.

My car's gas mileage is worse when I have to run winter blend, up to 2MPG.
With regard to Octane rating, it requires 91 or better. I don't really get better mileage with 93 but I do get a better response when I floor it. Yeah, a fraction of a second isn't much, but I notice the difference over 0-60 or a 1/4 mile.

The only time I have noticed ANY difference between gas grades/brands/blends is when I filled up with "real gas" instead of the 10% ethanol junk. Within a few miles down the road, the MPG readings on my Scan Gauge were about 0.7 - 0.8 mpg higher than my typical MPG numbers. I didn't realize until afterward that I had filled up with gas from a state that didn't require ethanol blends. That works out to about a 10% boost in MPG.

~Rick

wny_pat wrote:

srt20 wrote:
BTW I don't generally get better mpgs with a certain brand, though I tend to favor shell gas if prices are the same as the place across the street. BUT I will say my mpgs SUFFER greatly when using gas bought on an Indian reservation. Even with Indian gas being way cheaper it still doesn't come out better in a cost per mile.

I guess that depends on the indian reservation. Have heard the same thing here, but my car's engine (both cars) can't tell the difference. By the way, before I retired from hauling fuel, I loaded side by side the rigs that hauled the "indian res" gas and can say for sure that the gas was the same gas that the off res stations got. The only difference was tax on it.

But my cars can tell the difference between regular (with ethanol) and premium (without ethanol). The Honda much prefers the premium, gaining 6 mpg and the Ford only gains 2 mpg. I quit making special trips to the Res and buy my gas where ever I need it. My motorhome does not use gas.

The worst reservation I have found ( and I have stopped using Indian gas if I can help it), has actually been in western NYS. The Seneca nation in Salamanca NY. My gasser pickup gets about 3 mpgs worse and my diesel pickup gets about 5 mpgs worse with any of the fuel on that reservation. There is only 2 or 3 places that sell diesel in Salamnaca and they are all bad.
Last trip out I was able to fill the diesel up at the last Ohio stop on 90 and was able to nurse that tank until I headed back home. The prices for any fuel in NYS are stupidly high.

Octane rating has no impact on BTU's. Additives used to increase Octane simply prevent the fuel from detonating early, in higher compression engines. High compression engines will experience pre-detonation (a.k.a. Pinging & knocking) when using regular grade gas. This can cause valve train damage over time.

If your engine is designed for regular gas, mid grade or premium is a simple waste of money. If your engine is designed from premium grade fuel, being a cheapskate is gambling with your car's longevity.

Finally, to complicate matters, many newer cars have the ability to adjust to the grade of gasoline used. These cars can be identified by the term, Premium Grade RECOMMENDED, instead of REQUIRED. Those engines will retard timing a bit when lower grade fuels are detected. They will run fine, but performance MAY be slightly affected as well.....

At one point BP in Ohio was notorious for running higher than 10% ethanol. Of course that hurt mileage. Not sure if that is still a problem, but my parents had their car in for service, because it was running poorly, so the dealer tested the fuel, which is how they found out. Switched brands and things got a whole lot better.

srt20 wrote:

DougE wrote:
Premium gasoline does have a slightly higher BTU content than regular but the difference in mileage is virtually undetectable. If your engine is tuned for the better gasoline using regular could impact mpg as the electronic ignition may need to retard the spark to prevent detonation (knock sensor). Premium gasoline (branded) has a better detergent package and you would gain some benefit from cleaner injectors, etc.

Premium actually has LOWER btu than regular. Regular burns hotter and faster.

Only difference I've ever seen in mpgs from different gas blends is between using gas with some ethanol vs 100% straight gas. Straight gas will give a little better mpgs generally. But as with anything related to mpgs its almost impossible to get a perfect apples to apples comparison.

The amount of ethanol makes a difference, grade of gasoline does not

As far as brands of gas goes. I am only loyal to my pocketbook. I try to buy the cheapest gas I can find, have never had a problem.

Ok eveyone the no's win . So I will just keep searching for the cheapest gas I can find. Happy RVing.