Exhaust smell inside cabin?

[BabyBlue2010]

So lately, I've been smelling a slight engine smell inside my car.
1.) it smells when i have the heat on
2.) its only in two of four vents
3.) it only smells like that until the car heats up and i get going.
4.) and cars a 2010 Hatchback. LT

I did recently have an oil cap leak but that problem was solved by just tightening up the cap.
Any feedback?

[RicochetRandy]

Gasket leak?
Is the smell more gasoline-like, or is it burnt smelling?
I've also heard about the throttle body contributing to this sort of issue as well.
Let's hear a little maintenance history on it! Ever change your plugs or valve gasket?

Edit: typing on phone is potato.

[BabyBlue2010]

I don't believe it's a gasket leak. considering I recently had the problem of smelling burnt oil only when i opened my hood, well I fixed that. And Gas? Not at all. it just smells like the engine, It's really hard to explain it but It's the exhaust smell coming inside the car through the vents only when the heat is on. and only for the first few miles.
History? Nothing has been changed thus far considering it only has 33,000 miles on it. I do change my oil every 3,000 miles.

[petrified.rabbit]

this could be as simple as your rain tray is full of leaves (or snow or something) so the draw of fresh air is coming from the engine compartment. but it could also be a slight leak to the heater core.

if it is truly only with the heat on, i would lean toward the heater core, because just fresh air would come from the same intake. it could also be a smell that is only appearing when it is warm enough for you to smell it. Maybe the mechanic touched something near the vents with his greasy hands, and once the heat warms the old grease you can smell it.

[BabyBlue2010]

Thanks! I'll look into it and post my findings.