You can buy a Sproggy MK3.5 as a kit or just a PCB. With a kit you still need to buy the main Maxxim or Linear Technology and National Semi (for 12V) chips.
Oh, changing car oil isn't that hard. For the past 15yrs I only brought my car to dealer for changing oil 5 times because they offer free car wash with any service.
I can change the oil in my Matrix within 15 min but about an hr on the Supra because the oil filter location on the Supra is freaking hard to reach. It stuck between the side of engine block and the Turbo charger.