I am about to load my Troyer tunes tonight. One question I only have about 1/4 of a tank left of 87 octane. I want to load the 93 octane program. Would I be ok to still load the 93 and run up to the gas station and top off with 93?

THanks sorry if this is a lame question...

 

best bet is to run it down till fuel light comes on-approx. 4~ gallons left- 1/4 tank is too much fuel to chance mixing-also use a good quality gas-no ma &pa stations- if you have access to citgo, or sunoco- use them- or shell or union 76-phil

 

Thanks man....

 

Yep, load the 87-octane tune till your low fuel light comes on then fill up with 93 and switch. Remember, the 87 tune isn’t a slouch by no means, it still kicks butt

 

For some strange reason I get better MPG with the 93 shell than the 94 sunoco.

Never could figure that one out.

 

Hi.

Yeah - noticed that too. Around here, there is a crapload of ethanol in our Sunoco 94 - complete with nice big labels proclaiming that fact.

Not so at our local Shell pumps...

Cheers
Vic

 

Hi redman,

The guys are absolutely right - when changing from low octane to higher octane tuning, the advised method is to run the tank of lower octane fuel down to the lowest reasonable level without running out - so typically it's easiest to do this when the low fuel light first comes on, as you still have a few gallons left at that point, and can easily make it to the gas station (unless maybe you're living in a *really* remote area).

That way, you have as little dilution of the incoming higher octane fuel as possible, and thus get the best results, and avoid the potential for detonation as long as good quality fuel is used. (Just FYI, when going the *other* way, from higher octane back down to lower octane, you can make *that* type of tuning change at about 1/4 tank.)

Which brings up another point that was mentioned in this thread - the point about a couple of the guys getting better fuel mileage with their local Shell than their local Sunoco 94, due to the Sunoco fuel being "gasohol" - meaning 10% ethanol by volume. Ethanol/methanol is high octane by nature, but also has only 50% to at best, about 70% of the actual energy content (BTU's per gallon) compared to "normal" gasoline. Thus you will *always* get better performance and fuel mileage by avoided those ethanol-blended fuels - what we call "gasohol." Even though the Sunoco is 1 point of octane higher, it's the *energy content* that makes the difference. Excellent point, and I thank the guys for mentioning that, it's good for all to see. This is also why virtually everyone gets lower fuel economy in the wintertime, as winter blend fuel also have a lower energy content, due to the type of oxygenating agents used to reduce emissions due to much longer warm-up times in winter, etc.

Good luck & have fun with your new tuning, redman!