All of this is very true. It is necessary to have hardened valve seats if you want to run unleaded fuel. Otherwise it will burn the valves. A lead substitute can be purchased at any auto parts store or even a wal-mart for that matter. I am not sure on the statement made by rustbucket53, on whether you need to use it for occasional use. The way I look at it, lead substitute is relatively cheap, only needs a cap full to a tank of fuel and is probably worth the investment if it means I might lose an engine. I run it with every fill up in the Chevelle, and will with every fill up in my 50 when it is finished as well.
