Bad gas

[Silvertip]

Re: Bad gas

Would that explain why my BMW gets worse MPG with 89 and better with 93 where as my Chrysler seams to get worse MPG with 93 and better with 89?

That would depend on the design of the ignition and fuel systems on your BMW. Modern engines are fitted with knock sensors. Should spark knock (preignition) be detected by the knock sensor, timing is retarded to eliminate the problem. Therefore, reduced timing = less power = poorer mileage. Higher octane fuel allows the timing to be advanced farther than with 89 octane. Case in point. My Impala is a flex fuel vehicle. It performs better on E-85 than E-10 because E-85 has 104 octane. The down side is mileage goes down about 3 mpg because of the difference in "energy" in the fuel. Injector timing changes automatically to compensate for the increased fuel demand. All of this means that if your engine is designed to run on 89 octane that's all it needs. There is no advantage to running premium unless as I said, the engine has a knock sensor and the electronics allow for increased timing beyond what 89 octane requires.

 

[H20Rat]

Re: Bad gas

My Impala is a flex fuel vehicle. It performs better on E-85 than E-10 because E-85 has 104 octane. The down side is mileage goes down about 3 mpg because of the difference in "energy" in the fuel. Injector timing changes automatically to compensate for the increased fuel demand. All of this means that if your engine is designed to run on 89 octane that's all it needs. There is no advantage to running premium unless as I said, the engine has a knock sensor and the electronics allow for increased timing beyond what 89 octane requires.

Excellent description! Additionally, engines that are actually designed for it can get equal mpg's with e85, with substantially more power! (flexfuel vehicles aren't designed to take full advantage of it, they can just handle it.) A true engine designed for e85 has far more compression than gasoline would allow, either through static compression or much higher forced induction pressures.

Case in point, I have done some fairly extensive modifications in a turbocharged car to run e85 in a relatively optimized state. As part of that, I run boost pressures and timing settings that would destroy the engine nearly instantly if I were to run on gasoline. (I can switch back and forth with computer mapping though.) Without a turbo to increase effective compression, I wouldn't be able to take advantage of the high octane that e85 provides.

 

[izoomie]

Re: Bad gas

. I think all of the ethonal free is 90.

Ethanol-free gas stations in the U.S. and Canada

I have a friend that works for Shell in Canada, he says 87 has ethonal, but the 89 and 90 do not. He runs 89 in his small engines.

 

[dozer1013]

Re: Bad gas

I prefer to keep the tank full,even if ya don't use it much,the one time ya decide to go further,you don't have enough fuel. Last fill up of the season gets treated for storage. The added cost of filling up once isn't that bad.

you make a good point

 

[WIMUSKY]

Re: Bad gas

well the most I'd put in would be about 10 gals...just too expensive to fill up and I don't use it enough to justify filling anyway

you make a good point

That's the thing, once you fill it up, it shouldn't be a problem to add the 10 gals thereafter to keep it full.......

 

[dingbat]

Re: Bad gas

I prefer to keep the tank full,even if ya don't use it much,the one time ya decide to go further,you don't have enough fuel.

Empty or full tank, E-10 will continue to absorb and accumulate moisture in the tank. Keeping the tank full reduces the absorption, but it doesn't eliminate it. Over time, moisture levels will continue to climb until you get an abrupt temperature change the fuel separates. Been there, done that.

You would be much better served by turning your fuel over on a regular basis. I normally keep my 100 gallon tank half full unless I know I'll burn more fuel in the course of a day. I typically burn 25-30 gallon a day so I'm replacing 1/2 my fuel with fresh every outing.

 

[crabby captain john]

Re: Bad gas

Empty or full tank, E-10 will continue to absorb and accumulate moisture in the tank. Keeping the tank full reduces the absorption, but it doesn't eliminate it. Over time, moisture levels will continue to climb until you get an abrupt temperature change the fuel separates. Been there, done that.

You would be much better served by turning your fuel over on a regular basis. I normally keep my 100 gallon tank half full unless I know I'll burn more fuel in the course of a day. I typically burn 25-30 gallon a day so I'm replacing 1/2 my fuel with fresh every outing.

My marina does NOT sell E 10. The pumps are diesel or 90 octane ethanol free.

 

[limitout]

Re: Bad gas

I bought the boat in June and it had some gas in it, how old that was I have no idea. I've added a few gallons since then to that so what's in there is a mixture of that old gas and what I put in it. If I had to guess I'd say there's a gallon or less left in it now

As far as the tank capacity not really sure but if I had to guess again I'd say in the 20 gallon range

if you are only talking a gallon or two of gas then that's nothing to worry about but if you want it all gone then replace your fuel filters (not the fuel/water separator filter) and take two 5 gallon cans of gas with you and go run it out of gas, then add one of the 5 gallon cans and run that out of gas, then add the last 5 gallon can and head to the launch with it. doing this you have completely flushed everything out of that tank so go home and replace all the fuel filters again along with the fuel/water separator filter since they will have caught whatever was sucked off of the bottom of the tank and you want that stuff gone and not sitting in a filter somewhere.