Syn blends

So im beginning to wonder if I should begin usuing the high milage motor oil such as valvoline maxlife. I have a 99 5.3 silverado, with about 135,000miles. So far i have no oil leaks or any trouble (knock on wood). I currently use Mobile clean 5000. I and i change it every 2800 miles just because. Does anyone think changing to a syn blend would be a bad idea? I know "if it aint broke dont fix it" but i'll probably have this truck for atleast another 5 years, and I have heard good things about maxlife.

Thanks
FF18

Changing that often, I dont think it really matters what type of oil you use. Even conventional oil really wont break down that fast