the valves or rings are allowing compression blow by to enter the crankcase which causes excess pressure that is brought to the carburetor by the breather tube. your engine is getting tired or you have too much oil in the crankcase.
The 15.5 Briggs does not have an oil filter.
Briggs & Stratton part # 491056 NAPA filter # 1348
You can get that info on the Briggs and Stratton website. Just go to: http://www.ereplacementparts.com/briggs-and-stratton-parts-c-16758.html?gclid=CPCZj4vGr58CFZdM5Qodp3bDsA and enter your engine model number.
There are a couple different oil filters that fit a Briggs and Stratton 24 hp engine. The most common oil filter is a PE 105.
Try servicing the air filter.
For a Briggs & Stratton Intek engine "PH8170"
696854 is the Briggs Filter on my 24 horse now that is probably a Sears part number.
48 oz. without filter.
The fuel filter for a Honda self propelled push mower with a Briggs and Stratton engine is located between the fuel tank and the carburetor. The fuel filter is only about one inch long.
Yes, it has an oil filter and the Briggs & Stratton part number is 492932S.
briggs and stratton oil filter part no.696854 replaces 795890.
wal mart super tech filter # st3614 or Fram filter # ph3614