forgive me if this is in the wrong place of if this has been beaten to death, but the idea that oil knows only miles and cannot tell time is a little odd to me. case in point ... i've got two old trucks that don't get many miles. the one is my powered wheel barrow and plow truck. on it's best year it gets 300 miles. that being said, half of it's miles are in reverse backing up while plowing. being an 83 the odometer does indeed count backwards in reverse. not that it matters much. the other has seen 300 miles since 2011. its my back up heavy hauler and generally only gets used to haul hay. it is also somewhat of a toy, and is a truck i just like. now the plow truck gets way more idle time than miles and rarely sees the road, while the other still gets plenty of idle time it sees the road when when it gets uses, and usually with a trailer behind it. i'll freely admit that i'm from the "oil is cheap" camp. i usually change oil annually on anything that gets used. even if it is not needed, a 5quart oil change and filter only costs me about $15. an oil analysis costs as much or more, and an engine failure would put the truck in the junkyard. (can't put more money in the truck with an engine replacement than it's worth as a whole). i've got another car that has been sitting in the shed un used and un started for probably 5 years. i did an oil change on it before the last time i had it out and the oil may have 100 miles on it. now i agree that it hasn't been "used up" but who knows if it has collected moisture via condensation. maybe it has, maybe it hasn't but i can either pay for the oil analysis and know, or for the same money i can drop the oil and filter and know for sure. so if we go by the 3,000 oci for "severe use" on the two trucks (which i feel would apply), then the one truck should get it's oil changed every 10 years, and the other truck wouldn't be due for another 30 years (based on current trends). is there anyone here that would feel comfortable changing their oil every 30 years? how about 10? oil can't tell time -- only miles, right? not looking for a fight, just looking for some insite.