Maybe I am just imagining things, ~450:1 helped to quiet down/smooth out the idle noise on cold mornings on my tC...
Using super-tech TCW3.
This is a second time I am doing this treatment. Had about 2 tank "break" to clean out the system.
BTW - I never noticed, but Amsoil PI bottle has handy markings with gallons 5, 10, 15, 20... 15G mark is almost exactly 4 OZ. This makes it easy for me to make/dispense 450:1 concentration for my tC.