Lets start with the fact that glow plugs confuse me. There are are so many on the market (hot, medium, cool, etc.) and OS makes enough to help with my confusion. I need to purchase some for my .61 FX. I use either 10% or 15% nitro fuel. I looked at the manual and it listed the #8, A5, and A3. In the tower catalog it mentions there is also the P series plugs. What should I purchase? Also, any info on how to understand the various plug designations would be helpful.