I use Valvoline full synthetic. My grandfather, father, and uncles are swear by it so I use it too. I like it because its cheaper than Mobile 1. I do use a Mobile1 oil filter though. Autozone had a deal going for a while that was like $30 for 5 quarts and the filter. I use 5.5-6 quarts. Use to burn a quart every 1500 miles which stopped after switching to synthetic. Just for reference this is in a 2k sierra 4.8L