I got 6 gallons through mine. It died because the air filter came off and some dust got sucked down the carb. I just traded it in for another TRX 3.3.

Unlike planes, rc truck engines operate in a very dirty environment so regardless of how much you spend on a motor, it's not going to last as long as a plane engine. Traxxas knows it's not going to last forever so they don't build their engines to last forever because dust and poor tuning are going to kill more RC truck engines than anything else regardless of how well you engineer it.

This is compounded by the fact that a lot of people's first nitro engine is the stock engine, so you have a lot of people running their engine through the wringer while they're learning the ropes of tuning, maintenance etc. Traxxas and HPI both have a nifty engine replacement program that saves you $$$ trading in your old engine for a new one.

After you've become a guru at these things, only then does it make sense (to me anyways), to invest in a better quality engine so you can get the most out of it. Picco, OS, Novarossi, RB all make great engines for monster trucks.