Carb was bad last season. Flooding. Engine hydro locked. Changed fuel soaked oil. Engine fired right up. Just rplcd. with new carb, fuel and air filter. Started right up. Ran perfect. Drove from back yard to driveway. Let idle a few minutes to warm oil. Shut it down. Changed oil with B&S 30W to correct level. Now its hydro locked again. Took plug out. Turned motor over about 10 seconds. Spun freely. No oil blew out. Rplcd. spark plug. Hydro lock again. New battery. Ran fine til I changed the oil. Literally ran like brand new about 5 mins. shut it down,changed the oil and it barely turns over unless I take s plug out. Why was it running fine til I changed the oil? Again, flooding carb, hydro locked, chngd. oil ran fine. installed new carb, air/fuel filter, drove to driveway,ran perfect, shut it down, chngd. oil again, now hydro locked.