I assume because the winds from the right were not allowing air flow from the engine fan through the oil cooler.
Errrrmmm.... If you are flying in balance, it doesn't matter a rat's patootie whether you have a crosswind, tailwind or headwind, the relative airflow will always be coming from dead ahead. Same with your door popping open, if you are in balance, that shouldn't happen - assuming the door is rigged correctly. Judging by your comments, the previous owner just didn't take proper care of it.
But maybe I am biased, I detest every hour I flew in Enstroms.
