RC NITRO ENGINE "HOW TO READ YOUR GLOW PLUG"

OS and Turbo glow plugs go grayer sooner(easier) than Mccoy,traxxas or fox plugs; this does not make them bad glow plugs.
Actually when "A" new plug wire just goes slightly gray after a 5 or 10 minute hard run it means your very close to an optimal horsepower tune.
READING YOUR PLUG:
1} Wire and surrounding bottom of plug wet, with like new shiny wire = rich side of optimum power
2} Wire and surrounding bottom of plug starting to dry and wire starting to gray = very close to optimum power
3} Wire and surrounding bottom of plug dry, wire totally gray but not distorted optimum power
4} Wire and surrounding bottom of pug dry, wire distorted = slightly lean "DANGER!"
5} Wire and surrounding bottom of plug dry, wire broken and distorted or burnt up = extremely lean possible engine damage!
Note: You can only "read" your plug in a nearly new state(Wire like new and shiny) A gray plug can still operate good.A fter a plug has gone totally gray, engine performance can suffer greatly. To test the plug put in a new "GLOW PLUG" and if you do not notice a difference in engineperformancethen save the gray plug or put it back in the engine and run with it.
"MOST IMPORTANT"
If your engine does not feel or run right try a new glow plug before making any major tuning changes!