Was losing 1 qt. every 500 miles on a '93 dohc with 120k miles.
Tried mmo soak, twice last year, didn't do it.
Tried gm top engine cleaner soak upon someone's advice who had something to do with Saturn at some point in another state. Helped some, and seems to have broken up ring deposits into chunks that came out the holes, yet, only improved oil loss to 1 qt. per 750 miles. Did seem to have more power though.
Upon Saturn parts guy recommendation, and after finding the marginal improvement by the gm top engine cleaner ring soak, tried the engine flush kit they, Saturn, sell. Freaking wow! Engine running much quieter. Car charges up long, steep hills and can accelerate like this engine was brand freak'in new. Oil loss, currently, only 1/2 quart per 1400 miles. You should see what that engine flush took out. Unbelievable. After the flush and 800 miles, I could NOT see the oil on the dip stick. It was that clean!! Oh, I'm getting 34 mpg around town and better on a trip now. I cannot believe the improvement. I cannot believe it.