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Thinking about gas prices and weather to use regular or premium fuel in my gasser RV

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BGMAC

RVF Expert
Joined
Jan 28, 2020
Messages
868
Location
Cypress Inn, TN
RV Year
2016
RV Make
Forest River
RV Model
Georgetown XL M-369DS
RV Length
37ft
Chassis
F550
Engine
Titan V10
TOW/TOAD
2020 Polaris Slingshot
Fulltimer
No
I was not doing much today and I started thinking about the difference in using regular or premium in my RV. It is written in other forums that the Ford V10 performance and mileage will improve on 93 octane vs 87. So I took to the calculator and using 300 miles of travel with regular being $4.22 and premium at $5.34 per gal. (That’s what it is around here) I also figured 8mpg on regular and 10mpg on premium.

Well, the cost of fuel would nearly be the same running premium or regular. So if you do get better mileage by 2 mpg you can run premium and get some of the other benefits it would provide,

I also played with the idea of using regular gas and adding octane booster. It is a little cheaper then using premium, but I’m not sure it’s worth the hassle.

Anyway, just thinking.
 
I‘d say try it and see. Having owned a few V10s, my guess would be that you wouldnt see much difference, if any. The only fuel issue I ever had was with ethanol. The ethanol blends definitely robbed power and reduced milage and these days its hard to find gas that doesnt have some percentange of ethanol in it. But other than that, using regular unleaded vs premium unleaded probably wont yield any noticable difference. Same thing with octane booster. The V10 is a fairly low compression motor (9.2:1) and doesn't have the capacity to take advantage of high octane.
 
If your engine is happy with the lower octane, and not knocking, leave it alone. Higher octane does not mean anything to a low compression engine. Just waste of money.
The opposite is true if you have a high compression engine. Low octane gas in it will make it knock and ruin the engine.
 
What Buly said. Also though it doesn't apply to a 6.8, on lesser low compression engines it has been found that high octane gas can actually cause lower performance. So you would be paying extra for less power. Point being that if you don't actually NEED Premium, don't use it. If you did need it, you'd likely already know.
 
Just got back from our trip to Orlando to see my daughter. I quickly realized why I left. Man was it hot!
Anyway, I used 87 octane this trip and got 6.7 mpg. Not too bad with the heavier RV towing my wife’s car and appliances on a trailer. Now that prices are dropping I may try premium just to see how things go.
 
I would run whatever the manufacturer recommends. If it's tuned to run on 87, all 91 will do is empty your wallet faster.
 
I would run whatever the manufacturer recommends. If it's tuned to run on 87, all 91 will do is empty your wallet faster.
I understand what you mean, but engines aren’t really tuned to a particular octane much anymore. Now with computer control the engine will adjust to the conditions there in to give the best operation. This includes increased octane.

Some engines my have a higher compression which will require a higher octane. Lower compression engine can run lower octain, but may benefit from running higher octane when under stress due to timing advance.
 
I understand what you mean, but engines aren’t really tuned to a particular octane much anymore. Now with computer control the engine will adjust to the conditions there in to give the best operation. This includes increased octane.

Some engines my have a higher compression which will require a higher octane. Lower compression engine can run lower octain, but may benefit from running higher octane when under stress due to timing advance.
I'll say I half agree with this. If your engine is tuned to run on 91, the computer will reduce power to avoid knock if you're running 87. But if it's tuned for 87, the computer can't magically pull more power out of thin air if you run 91.
 

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