fuel system

You will eventually burn a valve out, you can use an upper cylinder lube, this will help a lot as well.

Lead acts as a lubricant for the valves but since we did away with lead, valves and valve seats have been built with better metal alloys so it isn't needed. It also makes fuel harder to ignite. Your car is supposed to be using unleaded fuel. That's true of all cars since the late '70s. Using leaded fuel will not hurt your engine but it will plug the catalytic converter. That will greatly reduce power.

Fuels today use other additives to increase the octane rating which reduces pre-ignition. They also have really good detergents compared to just a few years ago, but those detergents won't remove the lead buildup in your catalytic converter.