I'm running Camguard at the proper ratio in various aircraft. In my personal Cessna (200HP IO360) I'm discovering excessive spark plug deposits all of a sudden. It coincides with my use of Camguard. The deposits are located deep inside the lower plugs, not near the electrode, but down inside, by the insulator. They are brown/tan in color, looking kind of like dried dirt. They are not "rock hard" like carbon and lead deposits. They can easily be picked out by a piece of safety wire or paper clip. The deposits are chunky in nature and are quite large. I can easily break up the chunks and it looks like dust/dirt. My best guess is that since my engine consumes about 1 quart in 4-6 hours, I'm seeing the additive in Camguard forming this deposit. By 10 hours, the lower plugs are full of deposits. Weird... They don't seem to affect how it runs. I have not changed oil brand, type or viscosity. Nor have I changed any other parameters. A quick look inside the cylinder reveals nothing unusual.