Will running leaded fuels mess up your stock O2 sensors? I normally mix in some 100 unleaded octane at the track. I want to use some 110, too bad they don't sell any C16 it my track.

 

Leaded fuel will foul up the O2 sensors and if you have cats it will mess those up as well. Is your compression high enough that you even benefit from 100 octane?

 

"Octane" is a measure of a fuels ability to resist pre-iginition or detonation. It is not a measure of the energy content or even the specific gravity. If your truck doesn't ping on 91 octane fuel then you won't get any measurable advantage from higher octane fuel unless it is oxygenated. Some racing fuel has higher levels of oxygenation that allow you to run the mixture slightly more rich for some added power.
To benefit from higher octane fuel you have to also at the same time increase cylinder pressures and/or add timing.

Some people may tell you that running leaded fuel for just a few races won't do any damage to your cats or O2 sensors - that is completely WRONG. Do not run leaded fuel at all.

 

I know my WB O2 said not to use in vehicles that run leaded.