ensure the engine is probably scavenged of lead just before shut down
do they mean the Lead Bromide thats the result of combustion? and is actually a salt, and far from being a lubricant as clamed in the past? or is it the Tetraethyl lead which might have come out of solution with Avgas and left deposites before its burned and turned into a lead oxide and a bromide? or is it the lead oxide deposits or just plain old lead?
how does running at a certain RPM buring the same leaded fuel scavange the lead byproducs of previous combustion using the same fuel, when chemicals added to the Tetraethyl lead compond are designed to scavange the lead before it can be deposited during combustion, turning into lead bromide so it passes out with the exhaust.. (which freezez at 370deg C, hence leaves the light grey residue in the exhaust pipe)
I wonder if its a co-incidence that car engines became far more reliable once the fuels they used stopped producing a corrosive carcenogenic compound of lead during combustion?