ProXS 87 Octane Min

[MIZ-ZOU]

I've read that the ProXS motors take 87 octane minimum and that 89 will help idle quality. Around here, the only 87 and 89 octane fuel sold has 10% ethanol .

In the winter, should I be using 91 that is ethanol-free (especially when I use the big motor less in the winter) or just treat the fuel like usual and use the 87? Note that I have no problems with idle quality at all...

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tr200X2Seth &raquo;</TD></TR><TR><TD CLASS="quote">I've read that the ProXS motors take 87 octane minimum and that 89 will help idle quality. Around here, the only 87 and 89 octane fuel sold has 10% ethanol .

In the winter, should I be using 91 that is ethanol-free (especially when I use the big motor less in the winter) or just treat the fuel like usual and use the 87? Note that I have no problems with idle quality at all...</TD></TR></TABLE>

That's a loaded question, my friend!

Here's the dilemna:

Switching back and forth from Ethanol fuel to "non-ethanol fuel" has it's own LARGE drawback: Potential "PHASE SEPARATION" in the fuel tank.

The absolute "safest" bet is to properly treat your fuel, winterize your engine, and then DRAIN your fuel tanks (as close to DRY AS PHYSICALLY POSSIBLE via PUMPING THE FUEL MANUALLY). DON'T ATTEMPT TO RUN THEM DRY WITH THE ENGINE.... you DO NOT WANT ALL THE STUFF ON THE BOTTOM OF THE TANK IN YOUR ENGINE.

The "next-best" alternative would be a FULL tank of MID-GRADE fuel, treated well with stabilizer. This is the method most of my customers choose (and the mid-grade is used simply due to the likelihood of octane loss over the winter).

[Cyncwby]

I just got back from a 5 day houseboat trip with my 22' Bennington tri-toon fishing rig, 175 Pro Xs on a hyd. j/p. I have been doing **EXACTLY** as Don told me from the get-go. I use 87 or 89 oct. with the proper amount of Quickleen and Seafoam along with Merc Premium Plus. The engine runs like a charm and I actaully saw 44 mph gps with a 12 ft. bimini top up, loaded with fishing gear, trolling motor and 2 big batts up front. Not bad for pushin' a big heavy barn door through the wind.

I keep the boat in my RV garage all the time, in the winter I fill the tank and treat the gas the same, fires right off in the spring. Couldn't be happier with this engine or the info that Don has given me.

[MIZ-ZOU]

Thanks, Don.

I will continue to treat the fuel and use as normal. I may start using 89 in the winter, "just in case". I never drain my tanks as I have the boat out every 3-4 weeks in the winter (the water hardly ever gets hard around here).

I understand the phase separation issue, but would a person be better off to change to 91 and run it all the time, especially if it's the only ethanol-free option in your area?

[esdbass]

+2 on what you say Trashy I'd also add you need to continue to use fuel stabilizer and quickclean as well.

I like the Don recommended and tested Merc Quickclean/Seafoam and Marine Ethanol Stabil Cocktail

[egammon]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EuropeanAM &raquo;</TD></TR><TR><TD CLASS="quote">

Here's the dilemna:

Switching back and forth from Ethanol fuel to "non-ethanol fuel" has it's own LARGE drawback: Potential "PHASE SEPARATION" in the fuel tank.

</TD></TR></TABLE>

Are you saying this may happen instantaneously (as soon as the non-ethanol gas is mixed with the ethanol-laced gas) ??

I have found a source near my home that sells non-ethanol gasoline, and had planned to make it my regular stop for fuel. But I recognize that, on occasion, I might find myself having to buy whatever is available (probably ethanol-laced fuel) while away from home.

Is there a STRONG likelihood of phase separation, or is this more theorectical ??? (I understand that filling stations can't swap back and forth without emptying their tanks, but wasn't aware that this was an issue with truck or boat usage).

[EuropeanAM]

To be honest, I've never "timed" a test to determine how long it takes for Phase Separation to occur.

The POTENTIAL (and the likelihood) are both there. In a case such as yours.... IF you end up purchasing a fuel with ethanol content (or suspected to have ethanol content) while you're out of town.... try to run the tank down as low as "safely" possible PRIOR TO switching (and by switching, I mean EITHER way).

[egammon]

Thanks -- again.