With a wife, 3 kids, myself, and company vehicle, I do lots of vehicle maintenance each month. It is a pity that every vehicle uses different air and oil filter, as well as varied amounts of oil. Of course each has a different sized oil plug. The spark plug types are different, so are pcv valves, bulbs, etc. I prefer a quick reference rather than having to search through the owners and repair manuals each time. With 6 vehicles, I can never remember from one to the next. Nothing is more frustrating than to crawl under a vehicle with the wrong sized socket for the drain plug etc. I have gotten around this by taking a sharpie and writing reminders on the engine shrouds or on the underside of the hood, etc. Never again will I look at the 3 new filters on the shelf and wonder if one goes into this car. Never again will I crawl under the car with the wrong socket for the drain plug.