AMSOIL makes the same claim, 25k under "normal driving conditions"; 20K under "harsh, dirty & dusty conditions". I've been going 20-25K between changes since back in the late 1980's, hardly ever had to ad oil (only when towing a heavy load) & never had a oil related problem using AMSOIL. I usually sell my cars / trucks around 200,000 - 250,000 miles. I'm sure Mobil One is a good oil & will give good service. == there are no rules or regs. on the term "par synthetic" as to how much "synthetic" is in the mix. A drop, a cup, 50/50, who knows? The term "oil is oil" is not true, there's a huge difference between quality name brand oils & no name, auto parts or big box store oils.