Ditto on Blackstone Labs. They just settled my nerves concerning coolant getting into the crankcase on SS's Tribute. Then I found external leak at coolant pump. Whew!!
Our '99 Winny has a third-of-a-million miles on it ... runs well ... and with Blackstone's help hope to get half-million. I also have no ownership equity in Blackstone ... darn it!!
In our crankcase, we wish to have only Mobil 1, no cleaners or other stuff. Nothing snorted up the intake. Seems to work for us.
Good luck to you.
PS: I have visited that plant in Oakville ... hope to afford a Flex some day.