I like the side of the door because you can see it every time you get in. At the rate my Cummins uses oil/fluid (zero) I don't get under the hood much. On work rigs I put the label right above the odo, that way others can tell me when it's time to service rigs that I don't use much. I use the Dynamo underhood for filter/belt numbers, oil capacities/types, etc. Beats thumbing though the manuals.