Exhaust smell after oil/air filter change

About a month and a half ago, I took my 2005 Honda Civic LX to a mechanic for an oil change. He informed me that my air filter needed to be replaced as well, so I told him to go ahead and do so. Ever since I got the car back, however, I’ve been smelling car exhaust unless I push the button for recirculated air. Any idea what could be causing this?

He might have spilled some oil onto the exhaust manifold. I’ve done that. It’s easy to do. And sometimes it’s tough to get it out of all of the cast-in crevaces. Take it back and ask him.

I agree with the oil-on-the-exhaust theory, but I think any spilled oil should have burned of by now.

Hot oil has a smell that differs from exhaust fumes. Are you smelling hot oil or exhaust?

Yep, spilled oil. Nothing to worry about. It will burn off on its own.

I’d agree about the spilled oil and also think that its been a long time - but there are little crevices and such where the spilled oil can pool up and thus can continue to burn off over time. Eventually it sort of turns into a greasy sludge in some crack or crevice & can take a while.

However, it is also quite possible that - quite by coincidence - you may have developed an actual exhaust or oil leak. If this oil change was done by a “real” mechanic - and by that I mean not a quickie-lube or other corporate chain type of place, then I would go back. Describe the issue and ask them to take a look.

If it was a quickie-lube or other corporate chain kind of place you’re better off just finding a good, locally owned shop. Ask around for one with a good reputation if you don’t already have a place that you trust.

@mcparadise: It definitely smells like exhaust to me. (It’s like I’m constantly in back of a really old car or something.) Does burning oil smell that similar, or would I definitely be able to tell the difference?

It can smell like exhaust to you unless you’re familiar with the difference.

Again, just take it back and ask the shop.

Well, I don’t know why I didn’t do this sooner, but I opened the hood last night and discovered that the auto shop didn’t put the cap back on my engine after the oil change. It doesn’t look like oil sloshed around the underside of my hood or anything, so my question is, should I just buy another cap, or should I take it back to them and make them correct their mistake? (It’s been nearly two months since I took my car in, so I wouldn’t be surprised if they try to get out of owning up to their mistake. I admit that it was stupid of me not to think of taking a look under the hood, but that doesn’t excuse something that sort of oversight.)

Congratulations. You’ve discovered the mechanics’ secret to solving a great many problems…opening the hood and looking around. You should bill yourself $100 for a diagnostic fee.

First, check your oil level.
Second, call them and see if they still have the cap.
Third, reinstall or replace the cap.

Consider the new cap a really inexpensive education. It’s well worth that few bucks to learn the “open the hood” technique of troubleshooting.

Sincere best.

Did you check the oil level? That’s critical right now. And yes, they should buy you a new cap, but it might not be worth the trouble. Do NOT use them again for serviec.

Yeah, I checked the level, and it’s about midway between the first and second dot. Also, on further inspection, there was definitely some oil that spilled out. Since everything underneath is black, it’s hard to tell the extent of the spill. My main concern right now is how much damage could be caused by said spill.

I doubt there’s much, if any, damage, I’d just get a cap, clean up the engine compartment with a roll of paper towels (no power washing), and wait for the smell to go away.

I agree with Texases. You’ll be fine.

The way the system works is that the oil pump draws oil up from the pool in the oil pan and, under pressure, pumps it through the system. It then just drains back into the oil pan. The fill cap is just an opening to the oil return paths in the head. You pour oil in and it drains down the return paths into the pool in the pan. Absolutely nothing has happened that would have affected the engine. Your oil level stayed above the pump’s “pickup” tube, the pump kept pumping, and the oil kept lubricating, all as normal. The engine never knew the cap was missing.

By the way, kudos for being aware and for checking into the smell. This kind of awareness can prevent minor problem from becoming major problems. It did so in this case.