my slant wont turn over!

the dart that i just picked up had a froze up motor from sitting for over 10 years. i couldnt budge it either, so i used marvel mystery oil (pretty much same as tranny fluid i think) i let it sit in the cylinders for about a week with the plugs just loosely threaded in. went out just to see if i could get it free, and incredibly i was able to turn the motor over by the fan. it just took a little force at first, then moved freely by hand. i think the trick was to let it sit for a week. good luck.