This is a subject that can drive ya nuts. The fuels on the market today are lead free. Also, there are many additives that different gasoline companies are putting in to either help the environment, or cheaply boost the octane rating. The higher the compression ratios you have, the better the fuel needs to be. Sorry to say, the fuels aren’t making the trip. I use the best Chevron 92 Octane, or Conoco 92 that I can find. Also the BP 92 is acceptable. This is for use on engines with 7.3 to one compression or higher. On my engines I am running 6.8-1 and can run high octane water.

If you are running an engine with a CR of more than 7.5 to 1 as a daily driver, then you may be heading for problems. There have been a number of attempts to add ethanol to the fuels here in Idaho. Most stations have stickers on the pumps stating it isn’t more than 10% ethanol. The problem is ethanol raises the octane rating, but lowers the boiling point. Great combination for vapor lock on your air-cooled engine! In the summer here in Idaho, where temps can reach 107°, you can see a lot of cars on the side of the roads trying to cool down — and they’re not just VWs either.

We have also had some stations in the smaller towns selling 86 octane for 92. This is 86 out of the 92 pump at the 92 price. Just great when you are running 32 degrees max advance, and are on 92 octane. Then you get up the road and gas up again and it sounds like the pistons are swapping holes back there behind you. You then have to stop and retard the timing to continue on your way. I don’t know if they will ever come up with a decent fuel in the future. I just use the best I can find and watch the timing and listen to what the engine is saying to me on the road with a strange diet.

Ether is now showing up at the Chevron stations here in Idaho under the label MTBE. I am not sure about this yet, because I haven’t used much of it.