Asking people what motor oil they use is like asking smokers what brand do they smoke. LOL Seriously, you will get as many different answers as people who reply. I have read many, many, many hours of tests & research & have read for days on bobistheoilguy. I also read where a guy has a fleet of 12 diesel pickups & does oil samples every 10,000 miles. He has used just about every oil there is & used Blackstone labs to do oil anayl.. His conclusion was that the cheap wal mart brand of full synthetic performed as well as anything out there. So take everybodys opinion with a grain of salt. ANY engine can fail, & when they do MOST people just get rid of them & NEVER know what REALLY caused the failure. Most are not from lubrication breakdown. They are from component failures, or from oil passages that get blocked from poor maintanence & poor design of them. ANY full synthetic is better than the best regular oil. If you look up Schaffers oil, the guy there has more than one vehicle that has over 680,000 on gas engines. Only way to know for sure is to do oil anayl. on your vehicles every xxxxx of miles. I don't have the money to do that myself, as they cost almost as much as an oil change. But if Obama starts to charge tax on used motor oil, then one day it may be worth it to have them done. I have used Mobil 1, Royal Purple, Super-Tech in my current truck, all with great results & no issues.