Spark Plug Residue
I replaced my spark plugs yesterday (changed from NGK to Bosch super 4's) and noticed that the front 3 cylinders had a reddish residue all over the are within the combustion chamber. The back 3 cylinders had a greyish colour, with a very smell amount of red material.
Never seen anything like this before. Anbody got any clues??
btw I run mostly on LPG, with about 1/2 running on Petrol (std unleaded) every 2000Km. Gas system is an Impco, and I have a pod air cleaner sitting behind the Headlights. Car is a 95 XG XR6 with about 130,000K, and the headgasket has been replaced about 5000K ago for the second time.
Driving style is not agressive, and mostly country driving cruising between 110 and 140.