I have done oil analysis on several of our family vehicles, ones that have over 100k miles. Using synthetic, they all can go 10k miles per oil change according to the TBN count and show below average trace elements for that oil change interval. One of the vehicles with a 10k mile oil sample had LESS trace metal than average cars with a 5k mile oil sample. So that engine is wearing extremely well.

 

Not a Lexus....but still.....
http://www.synthetic-motor-oil-chang...oil-change.php

 

i've heard and read great things about amsoil. i've seen the oil analysis on an STi after the owner changed their oil at either 20k or 25k mile mark, i forget which. but the results were good and it was great to know amsoil lasted that long. i've heard stories and rumors of it going up to 40 or 50k miles--but again, these are rumors and stories, i don't actually know anyone whose had this experience. marketing is quite a funny thing because you can always twist things around to deceive the public.

For instance in this article published by Amsoil themselves on their own or affiliated website, just means it's more hype and propaganda, come on, where's the oil analysis? 409,000 miles without an oil change? how do you even define an oil change? full drain, full fill, replace filter? why yes, of course.. so you're telling me that the 18 wheeler is not going to eat up any oil during use? bull, of course it will, and as a result, you'll need to continue adding more oil to maintain its proper oil level. so the old oil gets burned, and the new one is replaced.. okay, but not really an full oil change right? regardless, you're still introducing new oil to the system. what about the filter.. their own website says the by-pass filter should be changed every 60k miles.. so i'm sure the one on the 18 wheeler isn't 409,000 miles old. just saying, don't believe everything on the internet.. i have no doubt their oil is good and can last maybe even up to 30 or 40k, but 400,000k plus? hm..maybe santa claus is real..