I run both off-road and on-road GT- the on-road engines just get so much more punishment, especially if you tune them for their full potential. They are on much higher revs almost all the time. It is good practice to replace the conrod after 1-2 gallons, there is just no doubt in that. After that it depends on what you want from that particular engine.

I also think it's good to pre-heat it as well, regardless of age, I think it's just common sense. I do it almost all the time. I have one made from an old hair-dryer and a can: it gets to the same temperature as the RC ones but in less than a minute. I think the RC heaters maybe heat the whole engine a bit better (I have both), but I don't need to wait for 10 minutes to get it up the temperature. However pre-heating is definitely not the difference between a 8 liter and a 30 liter life-span. So this is a personal preference, but conrod change is a must.