While I still buy Delo 15-40 for my diesel equipment, I purchased a lifetime oil change agreement from a Lithia dealership when I purchased my truck at 12k miles, even though I bought it used from a private party. The truck had been bought and serviced at a Lithia dealer in Montana, but the local dealer offered me the same deal... $595 for lifetime oil changes every 3000 miles up to 4 times a year, which is just the way I drive it. I figure the first 12 oil changes cost me $50 each (that's about what oil and filter would cost) and the rest are free. Or another way to look at it is that every time the oil is changed, the cost per change goes DOWN even more. By now at 68k I have had 18 or so oil changes, so cost of each is LESS then $35. I can barely buy the oil for that price now!!!
I DO realize that they use only CJ4 oil, but I figure at 3k oil change intervals, the CI4+ versus CJ4 oil quality issue is simply moot. And even though they occasionally (depending how busy they are) use an oil monkey instead of a mechanic, they are backed by the full dealership service dept. The only time I had a problem, (overfull and smelling it in the cab) I drove right back and they took care of it and chastised the monkey. IMHO,it has been a GREAT deal and one of the smartest things I have done for my truck!!!