Well heck, i just have to be in on this record setting thread.... read about the first 8 or 9 pages, just till tom had the loss of power... in my way of seeing the inside of an engine without actually looking in there, seems the loss of carbon build up dont fly, it happened too fast...more likely a loss of compressin due to lack of oil...no matter the quality , it still needs enough molecules of oil to fill all the voids bettween the ring and the cylinder wall....and as one other post said the the main and rod bearings as well...if the china engine piston and or cyl. is too hard it may never seat properly and is relying completly on the lubricant for compresion... about 20 years ago i got several truck loads of 460ci ford industrial engines , these were new, straight from ford. .. we ran them on propane in wind machines....the rings were chrome moly and would never seat using the dry fuel.... until we switched to cast iron rings... took a long time to get the ford people to pay up... but eventually their engineers admited the problem and it was settled...took two years...anyway, in my mind its just not enough oil .... probably hard metal in those particular engines , which probably varies alot from chinese production run to chinese production run.... would explain the different results from one engine to the next....