See full version: How to Start a Car That Has Been Kept in Storage
Hopefully, before the car was parked for the long term, its battery was disconnected, removed, and stored safely away from moisture. Then all you would have to do is clean the battery posts and terminals with a baking soda and water solution, give it a good charge, and reinstall it.
Give the suspension a good lube job and look for worn or loose ball joints, deteriorated bushings, rusted shafts, leaks at the shocks, and missing or broken bump stops. [links]
Thoroughly check your brakes as well. With the car up on a jack, rotate each wheel by hand with someone working the pedal. Each wheel should brake solidly and release cleanly. Your inspection should include making sure the friction linings, drums, and rotors look in good order. Calipers and wheel cylinders are subject to corrosion, as well as leakage, so check those, too. [links]
With the spark plugs removed, turn the engine over with the key several times to allow the oil you put into the cylinders to lubricate the cylinder walls and to prime the oil and fuel pumps prior to ignition. You should keep cranking the engine until the oil pressure gauge reads normal or your oil pressure light goes out before returning the spark plugs and leads back to their correct position. here
My car has 137000 miles.
My car has an automatic transmission.
Hi. The most common cause of this problem is worn internal engine components. The engine’s valve seals could be leaking oil into the engine. The engine would then burn the oil, causing oil consumption without any external oil leaks. Worn-out piston rings could cause this as well. You can try using oil additives designed to slow engine oil consumption to help with this problem, or you can use a thicker oil in the engine. Higher mileage vehicles tend to burn 1 to 2 quarts of oil every 1000 to 1500 miles; this problem is not uncommon for high-mileage engines. If you’d like to enlist some professional help with this issue, you can always contact a certified technician, such as one from YourMechanic, to diagnose and repair your oil consumption problem for you. [links]
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing [links]
Motor oils are lubricants, not cleaning solvents. Any modern oil has detergents in it and will slowly work to slowly clean things up.
1. Could high-detergent oils over short OCIs clean up carbon buildup on piston rings?
2. Any suggestions of oils with high-detergent compositions for this sort of situation?
Choose a quality oil in the right spec for your engine, do regular OCIs and keep track if consumption changes. That's it.
Drain and refill the oil. If it has been standing for a long time it would be worth doing this again after a few miles. Replace the oil filter. here
Check all the perishable components - hoses, tyres etc. [links]
And yes, checking rubber parts for dry rot and stuff like that is good practise when reawakening any vehicle but I'd save that until I knew it was running OK. more
I'll take a slightly different stance here - having a vehicle stand for a year or a little longer than that isn't that long, so I'd try to get it running first before I start changing out parts.
To expand on xpda's answer, and genericise it for any engine that has been standing for some time: