it is my experiance that the dipsticks in many vehicles are designed in such a way that either the oil doesn't show up as with my current car that has a yellow plastic end to the dipstick, or else the routeing of the pipe work to the sump means you are smearing any old oil over the dipstick,

therefore i propose a system of diposable dipstick covers, that fit over the end of the dipstick providing better contrast. This would be used with a bore cleaning patch, similar to those used on firearms to ensure that the oil depth in the sump is checked rather than any oil/greasey buildup in the tube to the sump is measured.