I thank all of you for your advice and information! When I said my engines were old, I'm talking 30-40 years. I don't know the history of glow engines, but I know they have been around since at least the forties. Most of mine are 1960's. The K&B Stallions maybe older than that. I have three that were my first "big" engines, and 25 years ago, they ran like new on castor oil and 5% nitro. I hope they are O.K.
now. They all have untold gallons of fuel through them, all pure castor lube. I know a lot of the "modern"
engines are of ABC construction, and make a considerable amount more power than did the older cast piston/steel liner engines, but from what I can tell, they don't last as long, and they are far more cantankerous to tune. Maybe they are too hot? (souped-up). A couple of guys I work with have nitro cars and trucks. One, called the T-maxx has a .15 engine,they refer to as a 2.5, has a claimed horsepower rating 1.3 horse! It also has a life expectancy of three gallons of the recommended fuel, and is VERY
hard to tune. I tried to help them tune it, as I was the only one that had any experience with glow engines at all. the recommended fuel for these engines is synthetic lube, 16% with 20% nitro. I wonder if using caster oil in these engines would increase the life expectancy? Just curious. Are the newer R/C and C/L engines ABC? I wonder if I need to do anything special before starting these engines that have been sitting. They are a little dusty and gummy. I know fresh fuel will free them up, but should I oil them, or clean them internally?

Thanks again guys!
Bud