Agree there is a big difference between 10k and 15k. I went 10k in the Land Cruiser based on my UOAs and those of others on the same engine. I suggested to the OP, sampling every 2,500 miles after 10k to establish when the oil starts to fail. I would recommend the same to anyone exceeding factory intervals and even then build in a bit of cushion (i.e. oil hits the used up point at 17.5k, run 15k intervals). I believe in maximizing value, but not being penny wise and pound foolish.You are not doing 15k, you are doing 10k. There is a significant difference.
And I am very happy to hear about your positive experience! Seriously, that is great. But not everyone will have the same result.
$1500 over 20 years time is a relatively small expense when the owner values long-term reliability. Speaking in generalities, not your particular circumstances![]()