Gas engines aren't built as strong as diesel engines. Therefore to produce more power out of a gas engine, you're putting a lot more wear on that engine. Power also produces heat, another negative effect on an already inferior design. Don't get me wrong both fuel types have their strong points. For a gas motor, I'm driving that for throttle performance. So I like the power on tap at anytime, no turbo lag. If I'm driving a diesel, I'm driving that for fuel economy, longer maintenance intervals and less stops at the pump. Under the right circumstances, either engine will last the same. But you can get a lot more hard work out of a diesel with better fuel economyWell....there are only 2 ways to cool a turbo....water, or oil....not sure about why you would think a diesel turbo would be superior to a gas turbo, unless your are talking about the engine, then, I would have to agree...if these engines shut down while stopped at lights, then, NO fluid is going to run through the turbo to cool it, while sitting there...yes, it's not running at the time either, however it was just running, and being heated by the exhaust which was just driving it...Mack engines require three minuets of idle run time prior to engine shutdown, to cool the turbo....I only speak of Mack trucks as that is what we used in our business in the 70's & 80's