About the only way to destroy a 4040 PS transmission would be to drain the oil and run it. Many years ago had a neighbor using a 4230 PS tractor planting double crop soybeans with a 8 row planter in field where I was combining wheat. Tractor would come to a stop and after a while would go back to moving. Did this no less than 4 times in an hour. Finished combining and drove over to the tractor and tractor owner ask if I had any HyGard in pickup. No oil on dipstick, leaking hose had run transmission out of oil. He put 5 gallons in tractor and went back to work. Never did have a problem with tractor and it burned in a barn fire 6 or so years later. Bought tractor for salvage and used transmission parts to repair another 4230 later on. Do not tell me the 8 speed PS is weak.