i've had an intake valve stick open on my snow trac twice now when temp drops down to around -15.the CHT. has never exceeded 250 since i put the gauge on and generaly when an engine over heats its the exhaust valves that stick the intake valve will free up when it warms up and woks fine otherwise other than a cracked guide i talked to a few aircraft mechanics they think its moste likely no upper cylender lube from unleaded gas a problem they ran into with aircraft motors desighmed to run off of high octain leaded fuel they added marvl mystery oil to fix the problem any other thaughts from some of the vw experts out there.