.....but I've put tens of thousands of miles on pre-unleaded engines, using unleaded fuel with no issues at all.
I agree with that Tiny. I believe back that (back when) i ran into that question, it was determined that with normal driving, one would loose 10% of the valve/seat life. Not a big enough reason to just do it because the leaded gas wasn't available in my book. I figured to go through the expense as needed.
