Dirty air filter can cause more vacuum in the air box and draw more oil in through the breather. Borescope the cylinder and do a leak down test. 172-260 psi is what the book calls for. Valve guides in my experience doesn't cause much oil burning. You typically only notice it when the machine is first crunk from oil draining down the guide after shutting the machine off. You can pull the breather hose off the side of the air box and get someone to rev it up and see how much blow by you have.#1 I have issues just wanting to see if I am alone. 185 lbs. of compression, I think the valve guides are bad.