Sorry to hear about your heater core. It is harder to remove than a radiator! I've used Gunk & Prestone radiator sealers and yes they work. I can't say at how many microns they are no longer effective, but for a heater core I'd sure pour in the sealer. The worst case is that the sealer could seal up the some of the cores in the heater if they were already marginal with mineral buildup. But hey, you need to replace it anyway.
I had to add a can of sealer to Pea Soup on the way to the races. It was 119 degrees on the track and the car's cooling was normal ... it wasn't adversly affected by having all that gunk floating around. I'm like you though in that I take pride in having clear looking coolant with just a touch of rose tint to it.
Thanks very much for the wool FDNY hat! I'll pass it along to one of the officers in our FD.
Last edited by Robby Ackerman; 12-31-2001 at 06:55 PM.