Re: lead additive for older engines?
Tetra-ethyl-lead was added to gas to increase the octane rating. An added benefit was some cooling of the flame front due to the increased octane rating, which helped to prevent valve burning.
Low lead (and now no lead) caused the refineries to reformulate the production of gas to get to the same (or actually slightly lower) octane rating without the additive, a carcinogen (tetra-ethyl). It is more expensive to produce a given octane rated gasoline without the additive.
Lead is a heavy metal element. It causes severe learning disabilities, especially children. Graphite is a form of carbon, also an element. They are not the same.
These are just my views and I'm probably wrong as usual, but I thought I'd throw my two cents in.
I wasn't born in Texas but I got
back here as soon as I could.