This works. Check your dipstick each day after putting the Seafoam in. Depending on how dark your oil is now, and how dirty the crankcase is, you can gaue the cleaning progress. First time I did this I went from golden/brown to jet black in a few days, about 150 miles. When I took the filter off it weighed about five pounds. There was sludge coming out of the clean side of the filter, the dirty side was completely full. And I had cleaned my valve covers before doing this. That was about 25K ago, at 185k. Been running Mobil 1 since then, 5k intervals. I have cut every filter open since then, they have gotten progressively cleaner. Last oil change the filter was practically spotless. Ready for another change, so I put a pint of Seafoam in the case last week. Drove about 200 miles, the oil barely changed color. Did the oil change today, cut the filter open. The dirty side was a little blacker than last time, but very clean. No sludge at all.Put some seafoam in your crankcase about 100 miles before you plan on changing your oil. Just follow the instructions on the can. I've used it several times with impressive results.