When do you use a "hot" glow plug vs. a medium? This is a general question for my education, but specifically why I am asking is:

I have just ordered a Tower Hobbies .75 engine and they recommend either a Tower plug or OS #8. A search on RCU lead me to a specific thread that mentioned the Tower plug is "similar" to an A3, which is #6 or hot. If this is true, and Tower's recommendation of the type of plug to use is true, then this two-stroke works equally well on medium plugs as well as hot, which leads me to the original question: when do you use hot vs. medium.

The fuel I usually use is 10% Nitro, although I may occasionally buy 5%.

Thanks!