Because the manufacturer realizes the damaging effect that dirty oil has on the critical parts of your engine. Even though your car or truck has a factory-installed filter, you must drain your oil periodically. Why? Because it’s dirty! The cost of an average oil and filter change today is more than $30. When you pay them 30.00 dollars you know than and there that in 3,000-5,000 miles, you will be back to hand them another 30.00 dollars for another oil and filter change. This money literally goes down the drain.

What you may not realize is that when you start your car to leave, all that clean oil has to do is splash around in your dirty crankcase, and you drive home with dirty oil. The longer you drive, the dirtier it gets, causing excess wear on the engine.