I have a B&S V twin that has a small oil leak at the front of the engine when going downhill. Everything else with this engine is excellent. Could it be the engine breather since that sets at the front of the engine?
Could be the breather, intake gasket or head gasket. The oil to come to the front of the engine and drip on the muffler when going downhill. I suggest you clean and degrease and dry the engine and then watch to see where the oil is coming from.
I use the old fashion farmer method. Clean and dry the area I suspect and throw flour or spray powder all over that area. Run the unit and you can back track the oil to its source. This works extremely well when you have hydraulic or other clear fluids. Shows my age.
These engines are notorious for sump gasket leak under the right hand cylinder when facing the cylinder heads. Good advice above on checking for sure where the leak is. IF sump leak, expensive gasket set to fix ~ $30 - $35. I can send you a Service Manual IF you like, address below, put in proper format and remind me engine model number and what you want.
What??? Haven't you ever used or heard of the UV dye that you put in the engine's oil to find oil leaks. The one I use needs a 465 nM ultra violet light source to light it up. I have engines where the oil appeared to be behind the flywheel to only for to be somewhere else like the oil cap seal. It also can be left in the engine. This really help on a pressure washer that developed a secondary oil a week later I found the initial leak. Oil was a secondary leak from the pressure pump instead of the engine as no UV dye wasn't present in the new oil puddle.
There also a version for the coolant systems which is why I know where my truck engine is leaking antifreeze. Some idoit used RTV and didn't it cure before putting the water/antifreeze back in so I got an intake manifold leak.
One thing about this is the light pen and glasses they provide in the kits is worthless. I had the UV wavelength light source that was strong enough to light the UV dye in full sunlight.