Suggestion:
Flushing the Engine is Only one of the Many Things you need to do "After 6 Years". Replace Hoses, Clamps & Belts, 6 Years in a shed- Tires are "Junk", You'll need to Flush the Cooling System & Replace the Thermostat after/If you get the Car Running, Change Transmission Fluid & Filter or Gear Oil, Lube (Very Well) Cheese and Wheel Bearings, Check and/or Replace Shocks & Struts, 35% Brake Shoes/Pads are still good, Replace Plugs & Plug Wires, Etc.
"Question is….is the Car worth it to you?"

{ 4 comments… read them below or add one }
Buy a bottle of engine flush…usually available at any auto parts store or walmart. Empty the bottle in, run the car and then drain the oil, (put a drain pan under the oil pan and take the drain plug bolt out) . You'll also want to check all the hoses and belts for cracks, check tires for dry rotting, Make sure brakes are not seized etc. Put fresh fuel in it before driving the vehicle, Or add a stabilizer and a bottle of injector cleaner would not hurt either. Would be a very good idea to change the antifreeze,brake fluid, transmission fluid and power steering fluid too…since it had been sitting for 6years. Keep in mind..all this if you plan on road driving this vehicle.
Good advice from Kyle. I would add that the tires are not going to be usable after six years – they will have permanent flat spots and the strength of the cords after all this time is dubious.
i would,nt bother flushing it. i would just change the oil and filter.
CRC is the best crankcase flush cleaner. NAPA and Carquest has it or can order it for you. Read the directions carefully! Do not drive the car with the cleaner added to an otherwise full crankcase full of motor oil. It's OK to add one quart of cleaner to your crankcase even though it's to the full mark on the dip-stick with motor oil. Add the CRC cleaner and let the car idle for 30 minutes for the best results. DO NOT DRIVE THE CAR.
Unscrew the drain plug while the motor is still hot. Let it drain for at least 30 minutes before changing the oil filter and adding fresh oil.