[kimlinh]

Your oil is not getting dark because it is the wrong oil. The air and oil filters also have little to do with it. It gets dark because of the incomplete and inefficient combustion of the Model A engine. Unburned fuel and water are the biggest culprits. Your modern car stays cleaner-looking longer because it is much more efficient. Raise the temperature of your engine with a thermostat, use a higher compression head, run leaner and advance your timing as much as you can without preignition will all help you burn your fuel cleaner, however, a Model A engine will never be as efficient and clean as a modern engine. Don,t worry about it, It's normal. Just enjoy your car, and if you don't use an oil filter, Keep changing your oil at 500 miles.