Here is what I have done in the past. First disconnect battery. Pull plugs, get a hand pump oil can, fill with diesel fuel, put a generous amount in each cylinder. Let this sit overnight, go back and do it again. Do this for 4-5 days. Don't get in a hurry. Then get a socket that fits retaining nut for balancer on front of crankshaft. Using a breaker bar or long ratchet try turning it slightly. You will want to rock it back and forth just a little. If it breaks lose just rock it back and forth a few times. Don't rotate. Then go back with a squirt of fuel in each cylinder. Let sit for a little while then rock it a little more. If it starts to move easily just rotate back and forth in larger arc's until you can completely rotate crank. Keep luring cylinders and rotating until she is smooth. Then squirt some good clean oil into each cylinder and rotate to clean fuel off cylinders. Let sit overnight. Then drain oil and replace and new filter. Put plugs in and fire her up. This is what seems a slow process but it sure beats busting a ring. After you get it fired up run it for a while then change oil and filter again.