I have 145,000 on my truck, no oil leaks, I change the oil every 3-4,000 miles, oil filter every other change, however had alot of radiator problems, some kinda tube under motor rusted out, big bucks, and the radiator had a little split in the side, since they're made out of plastic had to get a new one, big bucks, so I am now going to get the system flushed out every other year. I thought it was just a way for mechanics to make money by doing the flushing, also how could something rust that has anti-freeze in it. Just something to think about, always flush.
Now, I always wondered, if you use an additive to clean out carbon wheres the particles go?