I remember this just like it was yesterday, "25,000 miles Between Oil Changes" read the cover of Popular Science in 1975. Mobil One was just going to be introduced. That sold me right there. I've been a user in my autos ever since (except for the smoking station wagon). Mobil One never advertised that potential because I'm sure the auto manufacturers didn't want their buyers to see it, so Mobil One pushed the 5000 mile recommended oil change. The behind the scenes talk was that synthetic oil could lubricate forever but the filter would have to be changed to keep the oil clean. Then lately I started seeing Mobil One with 10,000 miles and 20,000 miles between oil changes. I actually called Mobil and supposedly talked to an engineer and asked why they don't advertise the 25,000 miles between changes and he denied that they have ever recommended 25,000 miles between changes. I mentioned the magazine cover but he said that was never true. I'm sure the magazine article was older then he was. I know it wasn't advertised so he never knew about it. I was shocked when I saw David state that Mobil One gave in and started adding petroleum distillate base stock to their product. I see Mobil One has a Advanced Full Synthetic and a Fully Synthetic oil. I think the Fully Synthetic is a real synthetic, it costs $15+ per quart at Grainger, $24.37 for 5 qt bottle on Amazon. This destroys my true synthetic theory. I always use a Mobil One filter.
Gary 05 AMB DST