Small Engines (Lawn Mowers, etc.): B&S lawnmover. Oil over filled,,,wont start..., lawnmover, throttle plate

Question
QUESTION: B&S lawnmover. Oil over filled, then mover would not start. Drained oil, removed sp plug and turned over engine. Cylinder pushed out oil. Dried plug and replaced. Still no start. Oil is dripping from muffler. After 2 days it will start if I prime the carb, but stalls after 5 seconds. Gas tank is full. What do I do next?  tks, pa

ANSWER: First off you need to change the oil it is contaminated with fuel, that's why it's over full. From trying to start it you tied too long and flooded the cylinder with too much fuel, allowing fuel to wash by the rings and into the oil crankcase. This will now cause 2 problems, 1. Not enough lubrication protection. 2. The viscosity of the oil has been compromised, now the oil is to thin to produce a good form of compression between the rings between the piston, and the cylinder wall. But neither will fix the prior problem which is why it wouldn't start to begin with, you need your carburetor cleaned well, and rebuilt.....That's why it is only starting on the primer circuit, and then dies out. It's main circuit is the one that takes over after hitting the primer bulb. The main circuit should pull it's own fuel up after the initial start from the primer. ..........Tom

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QUESTION: thanks Tom, I changed the oil. I used 40 weight, the engine label did not say what viscosity. I also have 5w/30. Would that be better?

Someone suggested putting my hand over the carb during the 5 seconds to create vacuum to clear out the fuel jet and that worked! Now it runs, but the speed keeps varying fast and show. rapidly alternating fast-slow-fast-slow. That thing that comes out from the pulley wheel and is attached to two springs and to the throttle plate keeps moving back and forth opening and closing the throttle plate and making the engine speed vary. If I hold it still then engine runs smooth and constant speed. I know you said rebuild the carb, but I tried this instead. Why does it run like this?  

Answer
It runs like that because it still needs a carb rebuild, the governor is trying to compensate for the lack of fuel it's getting......As far as oil straight 30 in a warm climate, 5-30 for winter or colder climates.....please remember to rate answer please..Good luck, Tom