Originally Posted By: Wolf359
Originally Posted By: raytseng
calculate out the MPG and use fuel consumed.
Did you actually do this? MPG tells you nothing about how long it takes to consume those gallons.
I think using fuel burned has its advantages because it already takes into account things like short tripping, cold weather operation, extended idling, high speed/spirited driving, leisurely driving, etc.
The tough part is figuring out what that amount should be per OCI if all you were given is a standard 10K mile figure from the manufacturer. You could be conservative, and assume that this 10K mile OCI applies under ideal driving conditions, for example with mostly hwy driving. Now, say your vehicle gets 33 mpg in such driving, then your amount of fuel burned would be 300 gallons (10,000 / 33).
Now, if during your next OCI your mpg dropped to 25 because you did less hwy driving and more city driving or idling, then you should drop your OCI to 7,500 miles (300 gallons x 25 mpg).
OP, if you're interested in some alternative OCI calculations that take into account a number of parameters (including fuel economy), check out this spreadsheet:
https://docs.google.com/spreadsheet/ccc?...p=sharing#gid=0