Okay, here's another one that will likely get 20 different answers, all contradictory. For the first time I'm starting to wonder about DOT ratings and what I should put in my Chryslers. I hate to admit to such ignorance, but it never really concerned me before. I was reading an article which stated that DOT 5 should not be used in an old car. Correct? (DOT 5 is silicone brake fluid, right?) More important, you CANNOT mix DOT 4 and DOT 5 because they are not compatible, will attack each other, and the seals. Yes? No? However, DOT 3 and 4 are okay for old cars and CAN be mixed. DOT 2 is strictly for older systems-- drum only-- and should probably be thrown out. Right? How often should people change the brake fluid in their, say, 1968 Imperial??? Thanks in advance y'all MM