I will be sending in a coolant analysis this weekend on one of my cars thanks to the offer from Stinky Peterson. I have a 1994 Pontiac Grand Am 3.1L V6 & a 2002 Honda Accord V6. Which should I draw my sample from? The Pontiac has Neo propylene glycol with a 5 pack of GM cooling tabs. The pressurized radiator cap is on the overflow tank so I don't know exactly what would be the best way to get a "clean" sample. The cooling system was flushed a couple months ago so it should still be pretty clean. The Accord has the factory fill with ~33k miles. This might be a good time to check it to see how it's doing before the warranty runs out. I had thought about draining & refilling it at 45k miles.