I'm with doubledutyemt. I don't care what HAL says. It will be every 3000 for me. It has worked for me on my past three vehicles totalling over 500K miles. It is simple. When the odo is divisible by 3000 evenly.. it is time to change. (or three months, whatever comes first) Oil is the cheapest insurance for engine longevity you can buy. Why chance it on a computer algorithm?