Welcome to the technology era. I've run Amsoil to 75k with regular oil analysis...and it always comes back ready to go. This was in an F150, 5.8L HO, regularly used to pull trailer loads in excess of 10,000 pounds. It did burn a quart of oil about every 5-6k. I run oil analysis on my Contour, I've yet to have a result that said I actually needed to change the oil, but since I take the sample as I drain it, it's too late...and it uses no oil between filter changes (12k miles give or take a bit of procrastination.) Also in a Mustang with a 302 and a 7500 rpm redline. 12k miles on the engine before I wanted something stronger. Over 300 1/4 mile runs, plus shifting at 4k almost all the time, and generous throttle usage during the entire 12k miles. Tore the engine down, upgraded the pistons (old ones had ZERO deposits, no visible wear...rings still had the grooves in them) and heads, and put it back together. The initial layer on the bearings was of course gone, but all parts measured EXACTLY the same as they were put in, as verified by my machinist. The hone marks in the cylinders were still very visible. If anything, the engine wasn't broken in yet. I switched to 20w-50 Amsoil at 1500 miles. This current engine (only changed the rings) will be run up to 3000 miles before the switch to try and run it in a little better. Again, oil analysis showed the oil to be like new. No additional oil was ever added to this engine.
Amsoil is a proven product, and there are plenty of people with over 100k and no oil changes...oil analysis shows good. Amsoil has a very good warranty on their product, and has had so for over 30 years, to the best of my knowledge. Probably trillions of miles...and NO claims. If you can't believe their track record...you're not going to believe anything.
Get out of the 60s, and into the next century.
