Greetings, that engine carries the escape at the head of the vehicle, when there is an inclination, the oil level at the top of the head increases as much time as the persisting inclination. It is likely that the cylinder valve guide that is wet is already worn as well as the valve seal; There is an oil product that could help with this, it is called Restore, it exists for 4.6, and 8 cylinders; Pour it to your engine where you fill the oil and start the engine. Product molybdenum bisulfur content seals micrometric wear walls and valve stamps are softened on the contact lips with the valve. I hope it works for you. A hug