2002 gt center engine under cover necessary?

Employee at the oil change place stated that this cover can be left off. Said that leaving it in place causes greater heat to be retained by engine, tranny, oil pan, etc. Leading to faster deterioration of oil, fluid, etc.

Any opinions on this?

Damn thing keeps falling off anyway.

Any heating of the engine by this cover is unmeasurable. None of your components rely to any extent on airflow under them to cool them. The cover protects them against debris flying off your wheels or already on the road. Leave it there - but it's not critical.

Rule #1. Never listen to anything people at an oil change place say. 90% of the time they are full of shit.