What would happen if there is little oil in the valve train?
Valves are designed to fit into their seats perfectly and allow for a very little leeway. If your valve guides and seals are leaking, oil can accumulate on the top of the valve and cause it to lose its seat or create a gap. This could cause compression issues, which lead to poor combustion and power loss. via
How do I check my PCV valve? (video)
What are the symptoms of a burnt valve?
Bent or burnt valves can also cause your engine to misfire. This means the engine may jerk, stall, or hesitate when your car is in motion. Your vehicle's fuel consumption could also increase if it is misfiring due to a bad valve. These are some of the many symptoms of a bad exhaust valve or intake valve. via