I used to just have the Jiffy Lube boys slap in a new air filter when they showed me a dirty air filter. But yesterday, I took out the filter to look it over. The air filter holder, an "air box", I guess, didn't make sense to me, though. The bottom black plastic part seemed to have no opening to let air in. The filter goes on top of that part, like the lid on a tupperware bowl., which doesn't make sense to me, Does anybody know where air enters before it goes through the air filter?