Both Shell and Chevron use Techron as a cleaning agent in their fuel. This is probably the best additive that you can get to maintain a clean fuel system and combustion chamber. As to you using the higher grade of fuel, you should not need to worry about harming your engine. I occasionally run a tank of 93 through mine, and it seems to like it (a lot). I make do with 87 Chevron or Shell routinely, and recently when I pulled the intake manifold, the injectors, and the intake, all the way to the valves was clean as a whistle. I'm happy with the stuff. I have not a clue why you would have 190-195 pounds of compression, unless someone took a serious cut off the head, or crammed in an ultra high compression set of pistons.

Bill
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Those who beat their swords into plowshares, will surely plow for those who did not.