Hey, you'd probably never notice anything, but my only note about your comment is that you need to be aware that there are actually TWO factors with each type of fuel; not only is the octane important, but the flame temp.

Race gas is always your best option because not only is it high octane (higher resistance to ignition, but once ignited, it burns hotter than anything else.) If you mix it with anything, you're really defeating it's true purpose. Hotter combustion=more power.

If you're only looking for resistance to detonation, pump and xylene are just fine and much cheaper. I never put any lubrication when I put it into my tank. Just for reference, I put xylene in about 80% of my fillups from the time I had EM until just before I went overseas...probably every tank for a year and a half. I didn't notice any damage to the rubber in my fuel tank (the fuel pump gasket and fuel pump/filter assy.), nor along the hoses to my fpr, nor in the hoses from fpr to injectors, nor the injectors themselves.

FWIW