Originally Posted by ka9mnx
"This being said, however, it is still not recommended to use synthetic oil in engines that have experienced significant actions - specifically, those that have reached around 75,000 miles on the odometer. This is usually a signal that the engine is getting older and is more susceptible to wear on its inner gears and moving parts."
WOW! When I bought my F150 at 182k miles and B2500 Van at 162k miles I switched them to synthetic. Oh my, what have I done to those poor engines, transmissions and rear diffs?
Lol and I switched a 290k mile 89 Caprice to synthetic and ran it until 335k miles when it got too rusty. Clearly the synthetic oil caused holes in the frame. Lol.
I also run synthetic oil in my 44 year old 350 Oldsmobile V8 and 36 year old Chevy 305 V8 with tons of miles on them. I put 100k miles on the 350 in the past 13 years. Total mileage unknown, but likely well over 200k. I didn't read the whole article, the quotes posted in here are enough to discredit the entire article.
Come to think of it, every engine I've had was high mileage and I switched all to synthetic oil. I don't think I've ever had anything as low as 75k miles.