Briggs and stratten help needed

So, my $2300 lawnmower has 66.8 hours on it. Ove owned it since new, a few years now. 

Last sunday, after moeing the 1.5 acres i mow, it started burning oil at an alarming rate. This was blades off, riding at 3/4 throttle on flat paced surface. Actual consumption unknown at this time. However, oil smoke thick enough that i font have to worry about mosquitoes for a while. Literally a dense fog of oil smoke over my yard and street. 

Still runs fine. No noises, no apparent lack of power in the few hundred yards ive driven it. 

Started trying to diagnose before condemnation of a bad engine (inotek 18.5 ohv briggs and stratton)

Pulled plug. Signs of oil on it, obviously. 

Checked oil level: between the dots, as clean as it was two months ago when i changed it and the filter. 20w50 and wix since new. 

Loosened dipstick and ran emgine. Dipstick bounced 2 inches out of tube. Pulled dipstick entirely, and shot oil onto the underside of my balcony 10 feet up from the fill hole. 

Pulled crankcase breather hose: drips of oil, smoke while running, no excessive pressure or vacuum obvious to my thu.b when capping the tube. 

So, im pretty sure i lost the ringpack. Its all i can think of. Im hoping im wrong, but dont know where to go from here. Im small engine stupid. The insane pressure in dipstick tube is what leads me to this conclusion. 

What do i check/do from here? What am i missing in my diagnostic chain? Anyo e have another engine for me they can bring to the challenge if this ones berkeleyed?

In reply to Dusterbd13-michael :

Sound like a bad head gasket. https://m.youtube.com/watch?v=A9n2RLIR_Xs

Edited to add, I have almost 600 hours over 19 years on one of these engines in a Craftsman lawn tractor.  I don’t think the head gasket would be a terrible job, I’ll bet the head bolts didn’t get torqued properly at the factory.   I wouldn’t give up on it yet. 

Check your engine warranty. Depending on engine it's 12 to 36 months

In reply to 11GTCS :

Good diagnosis but not so great execution. "I'm very experienced at this". "I don't own a torque wrench." Grease on head bolts etc. That was tough to watch. 

But good diagnosis. I would have thought crankcase vent system at first guess.

In reply to fasted58 :

I take no responsibility for the mechanical skills of the U tuber .

 I’ve had to repair a few things on mine over the years.  Valve adjustment at around 400 hours, it stalled and wouldn’t restart when hot.  The valves were about 0.002” over factory settings and that’s all it took.  The fuel cut off solenoid on the bottom of the carburetor got weak when it got hot a bit after that which would stall the engine.  Voltage regulator failed and the battery wasn’t getting charged.  All diagnosed with on line searches and watching a couple of videos.  It helps that I’ve turned a wrench a few times and take the time to look up the critical stuff on the manufacturer’s website.  Just tick under 590 hours as of last Friday. 

Compression test and a leak down test.

Pressure is going where it is not supposed to go.

That being said, you know which cylinder has the issue.  It is just a matter of teardown until you find the problem.

My first thought was crankcase vent as well. Hadn't thought about a head gasket but that looks like a very valid diagnosis. Guess I'll pull it apart and see