Let's get this out of the way. I used Mayhems Pastel for 4 years and didn't touch it. I'm a terrible enthusiast
I'm honestly impressed with now well it did hold up. I had my pump on High and load temps were a little over 60C, so no harm no foul. Just... a marathon week of cleaning ahead.
Things looked pretty much as expected when I opened up the block for the first time.
The black plastic top is in great shape after just rinsing it out, so no issue there.
I scrubbed the copper plate with a toothbrush and tooth paste for about 5 minutes and made pretty good progress.
I'm not worried about the oxidized patina, but there is still some hard gunk deep down in the grooves. I have a Mayhems Blitz kit (parts 1 and 2) coming, but I was wondering if I should treat this with a vinegar soak or something first. Seems part 1 is just for the radiator, and part 2 needs to be pumped through the loop for a period of time. Is part 2 going to be enough to get this out, or is it just a pH neutralizer? Should I rig up a way to soak this in Blitz part 1?
Any thoughts are appreciated. Pics attached. Thanks!