I had my first attempt at maintenance on my mower and it didn't got well. I changed the spark plug, had the blade sharpened and drained the oil from the mower. I purchased a 20 oz container of oil and poured the hole thing in the mower. I did not know how to add some and then check the dipstick until the full line is reached. Without know I put too much in I started the mower and heard a loud rumble that startled me and I turned it off immediately. When I attempted to restart it I could not pull the start cord until after many attempts. When it did start up it sprayed oil out of the muffler. I shut it down again and started to freak out. I called the hardware store and my father who advised me to drain the oil and start over. When I pulled the spark plug oil poured out. There is oil everywhere. I drained some of the oil and then mowed my lawn. My husband and I thought the noise and smoke would stop once some of the oil burned off. The smoking stopped however the loud rumbling did not. It is new last season. It is a Briggs and Straton push mower. Is there oil in something important? Did I ruin my mower in one season?

I would guess you mnay have a plugged up exhaust, remove the two bolts and clean it, I would start it without the muffler and see if the rumbling noise is gone. Good luck. Make sure oil is at the proper level.

Wow. It is possible that you may have damaged the mower. Sorry. Good try on doing the maintenance yourself. Is it otherwise running smoothly except for the low rumble? For now, the best thing is to have a professional take a look at the mower and see if it needs further repairs. Does the rumble begin when you start the mower or when the blade is engaged? Is the rumble just from the engine or does it come from somewhere else? The rumble may be an unbalanced blade or loose blade, both of which are dangerous.

Otherwise, you really need to educate yourself on mower repairs before you attempt anything else. Read the service manual which is probably online. Check out small mower repair at the library. Most of all be safe.

If you had ALL the oil drained from a briggs and stratton engine, it would have held the 20 ounces with no problems. Briggs did drop the oil bottle down at one time to 18 ounces, but 20 ounces would have been fine in ANY briggs engine. What I think happened is that you did not get ALL the oil out of the engine to start with, now you may have irrepairable damages. Now if this is a larger briggs engine it could have held from 46 to 54 ounces depending on the engine. But all the smaller briggs, say 6.5 hp and less should do fine on 20 ounces unless otherwise noted in the owner's manual.