I use PBX 5W40 exclusively in my '04 Ford 6.0 company van, it is now up to 240K miles, no oil-related troule whatsoever, it is on it's ORIGINAL variable-vane turbo, which spools up as well as it did new. Hauling 9K in total weight every day, occasionally 3-7K tandem enclosed trailer in addition, engine runs HOT in summer, I usually look at the cartridge oil filter when VIOC changes it, barely looks dirty after a 5K OCI. Usually only uses less than a quart in 5K too. I'm a believer, now if they could get the price down a little...