Oil analysis from Valv Extended Protection 5w30 with 2000k mile heavy trailering through the south in June vs Mobil 1 5w30 with no trailer towing. That Extended Protection is good stuff. This is with 4.8 V8.
Well, gross combined was 11,900 lbs. I can’t know for sure how heavy the trailer was (tongue weight vs trailer wheel weigh) however, empty weight of the truck is like 5700 or so (If I recall). GCWR of that truck with 4.10 gears (I have 4.11) is 13,000, so its having to earn it’s money. Went about 2200 miles with it.