How many stress cracks have you seen that originated from the lifter valley?
Answer - none
OK - lets try - how much faster do you think the
oil will drain from a painted versus an identical
oil wetted polished cast surface?
Answer - not much if at all
The encapsulating dirt idea at least sounds viable. Except that, if the adhesion fails at any tiny spot, you are introducing debris instead of containing it.
At least the stuff does really look cool - - if you had a clear intake so people could see it....
I still don't like paint...your builder will disagree...if you put ten builders in a room five will be on either side of this discussion
