I've never had any problems with my moon roof. My 4th Gen normally is parked in the shade or garage. The last two days, I've had to park it in the hot Southern California sun during the day. When I opened the moon roof and it reached its fully open position I heard a strange noise. It sounded like a belt slipping. After sunset I opened the roof again and no noise. The same thing happened two days in a row. When I used the tilt function, the same slipping belt noise happened. Is this a sign of an upcoming problem?

 

Probably not a problem...I've heard that low viscosity lube slip many times....my Max has been in the Nevada and Southern Cal sun for 4 years and the roof (slide or tilt mode) always sounds the same...a slight humming, but no mechanical evidence of hesitation or slipping. It's just freer in the heat and makes that louder humming noise.