Read my link from post #7. VP C-5 got 6th place in the test. If your calculations are correct for VP C-5, 4 points is 4 x 1/10 or .4 rise in octane. Snake oil? I agree with mixing race gas with pump gas, but it is a hassle. I was hoping for a silver bullet, I guess. I have been mixing 100 LL aviation gas with my 91 pump stuff because my boating is in the sticks of Eastern Oklahoma with no race gas available. The written analysis from the airport FOB stated that the 100LL was actually 110 octane this summer. I asked the FOB manager why and did not get a good answer. Any pilots out there with insight to this?

https://en.wikipedia.org/wiki/Octane...MON.2C_and_AKI

Found my answer to my AV gas question.

How would you test the octane. Is there a tool?

Certain labs have a variable compression single cylinder motor to do these tests.

Put some of this in your JDeere and cut your mowing time in half

http://www.ebay.com/itm/The-Best-Fue...NRzQN~&vxp=mtr

Good question. It would be nice to be able to confirm octane, and a simpler way to confirm the presence of ethanol in pump gas.

Alot of companies sell cheap ethanol % checker's.

Again, octane is tested by just a few labs that have variable compression motors. No cheap self test for this.

Put a mark half way up on a bottled water bottle with a sharpie. Put another mark approximately 10% higher than the first mark. Fill the bottle to the first mark with gasoline to be tested then add water to the next mark. Shake, then let sit for a couple of minuets. If the water settles to the bottom, good gas. If the water doesn't settle, ethanol. Pretty cheap way to test!

We have a tester. Works really well. So far since we started checking we have not had any ethanol in ethanol free fuel.
As far as the outboards go I have tried higher octane fuel and never say any difference in performance with outboards.
Minimum is 91 and I have run 90 ethanol free with Aces IV additive for 5yrs no issues.
Anything higher than 91 is waste of money IMO for outboards unless you are running high compression heads. Is there something you are not sharing David??????:ernaehrung004:

Hey All, I was wondering whether the motor manufacturer would treat any damage due to the fuel additive as a problem. I have no experience with any of this but is it possible to damage the motor because the octane gets to high. Scorch or burn any internal components. I thought the fuel burns hotter with higher octane but once again I have no experience with Boosters of any kind and have never used them.

I don't think Mercury could identify if one used an additive in the gasoline if the fuel system is empty, except for the statement from some of the octane boosters that they leave an orange residue on the spark plugs. Higher octane just is used to control knocking (pre-ignition) from too high compression. It really does not "add" power or run hotter. Ron, I just want to have a little "cushion" in my fuel to guard against pre-ignition due to fuel degradation or just bad gas. Good to know that 91 is adequate from your experience. I wonder if the Mercury ECU is adaptive like the one in my Porsche. It really likes 93 octane, but in Oklahoma, you have to "make" it. It will run adequately with 91, but really needs 93. Will increased compression increase HP on a SX? Is it achievable? Would the ECU need a new tune? So many questions! I wish it was warmer and my F***n lake was not flooded again for the 5th time this year - I would be boating!:grinser010: