91 Octane Requirement (1 Viewer)

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As far as I know all 87, 89 or 91 have 10% Ethanol, unless sold differently as a separate non methanol grade and at big $$$ premium (like Sunoco does at some places).

Come to Minnie-soda, all 91 that I am aware of is ethanol free. One of the few benefits in this State. Pretty sure SD and Wi. 91 is E-0 as well.

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Diesel fuel is also adjusted for the balmy weather in Mn.

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I remember the Ziebart commercials well in Upstate NY. And the rust that people figured out that it caused but some still did it. My grandfather owned and operated a Texaco station and his theory, and it is a good one, is to not wash your vehicle in the winter. Heat is a catalyst for rust and if it stays cold enough then it can't form. Works better where it doesn't above zero F° for weeks at a time. I have a heated garage but park my vehicles outside for that reason there is truth to it.

Had a 67 Mustang and by the mid 70's the floor pan dropped out of the passanger side going down the highway, rusted out. And it was downhill from there. Many claimed the rusting back then was caused by the recycled cheaper Japanese steel that was being imported instead of American steel. There was a lot of action to stop the importation and use of foreign steel

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Traditional undercoating makes rust worse.

There are shops that do Fluid Film but it is not widely used. Most people simply don’t keep a car for 10 years.

I climbed under my Taco for 11 years and sprayed FF on the frame. It helped, not perfect and a PITA to do. But not a lot of other options.

My GX picked up in Nov. spent its first 4 years of its life in Texas during winters it was owned by snowbirds from what I can tell. First thing I did when I brought it home was take it to a shop that does NH OU Undercoating. It is basically FF that DuPoint made even better. NH OU started and still is mainly in the NE but are spreading West.

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After watching it being done professionally with a high pressure wand I will never do it myself again. He got in places I never ever considered. Almost 5 months later the stuff is still dripping off into my driveway.

If I do get a new GX550 or LC250 first thing I would do is take it to a NH OU Undercoater, they have a wax that they apply but will only do it on new vehicles. The guy that sprayed my GX said mine had less rust on it than some new vehicles that come in with less than 100 miles on it. Obviously moving would help with rust, or lack of.
 
My brother in law is one of those old school Vermonters who decades ago kept telling me to squirt some used motor oil around the frame, wheel wells, fenders, inside the doors and other nooks and crannies. I was always tempted but never did. He also worked at a Cadillac dealer in Burlington as a bodyman. His body work was exceptional and lent credence to that suggestion …but I could not think of getting over the smell of used oil all over. Again, never did it but as almost a lost cause in northern Vermont, I would do it if I was still living there. He is and his cars seem to be in great shape
 
91 is zero-ethanol here in MO. I buy it for all of my small engines to avoid the negative impacts caused by E10 (which turns lightly acidic when exposed to humidity and will really mess up fuel lines and carburetors in engines that aren't used constantly). Using the 91, some Lucas UCL, and Sta-Bil results in all of them starting right up after sitting all winter. I don't even bother to drain fuel out of the carburetor bowl.

Also - I just posted some pics of my DIY Woolwax Black undercoating for my rig in my build thread, which I first applied in 2021 and then re-applied this weekend, with a side-by-side comparison of how things looked. I used the Kellsport gun to spray it on with an air compressor, and also used Fluid Film inside the frame. It completely stopped any rust progression on my rig. Kind of tedious to do in my driveway, but I won't need to apply again til 2027.
 
Interesting that some states have ethanol free 91 octane. Here in Florida 91 -93 octane premium is 10% ethanol. There is ethanol free gas available at a few locations but it is substantially more expensive (like an extra dollar per gallon) and is generally there for use in boats, where the open vented fuel tanks allow humidity to interact with the fuel making ethanol gas a big problem if stored for a long period.

I can see a mpg improvement with ethanol free gas regardless of octane, but not from using 10% ethanol 91.
 

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