Oil Seal Leak

Depending on which seal is leaking, they could have disassembled the engine to get to it, and poked a hole in it. That would take considerable time. If the oil change was done at a speedy-lube place, they don't do engine repair so there would be no point in purposely causing damage.

On a lot of engines it is common for old oil to run all over the engine when the filter is removed. That's due to the design and difficulty in getting to the filter. That oil can also be very hard to clean off so most people just let it burn off later but it usually doesn't cause a lot of smoke. Most mechanics don't wash it off with engine degreaser and water for fear of causing other electrical problems which are also common.

At the far extreme of coincidence, if a seal or gasket is going to develop a leak, that can happen unexpectedly anytime. The question is, where is the car when that happens? If it just had the oil changed, you blame the mechanic. If it happened in the middle of a two-hour drive on the highway, you blame the person who worked on it last a month ago, or you realize it's just a normal occurrence that needs attention.

While coincidence that it happened just when the oil was changed is certainly possible, it does stand to reason something happened there, but it very likely was not intentional. The first thing to do is determine where the smoking is coming from and clarify what you mean by "profusely". To some people "profusely" means they can see a tiny wisp of smoke if they look closely. To others it's not that bad if they can still see the car behind them.

If the smoke is coming from the tail pipe, the oil was likely over-filled. Draining some out until it hits the proper level will solve that with no damage to the engine. If it's leaking low near the bottom of the engine, spilled oil may be burning off or they might have "double-gasketed" the oil filter. That's when the rubber o-ring seal from the old filter sticks to the engine and gets overlooked, then the new filter and gasket is screwed on over the top of it. Usually the old gasket will blow out well before the car makes it out of the shop, but that doesn't result in smoking. That just results in a huge mess on the floor. It has or will happen to every mechanic sooner or later. The only harm done is embarrassment.

If the smoking decreases the longer you drive the car, it most likely is just spilled oil. If it continues, have it inspected at a different shop and have their diagnosis put in writing. Don't mention the name of the shop that did the oil change so you don't sway their diagnosis or judgment. If the two shops are friends, the second one might tend to downplay the importance of their findings. If they don't like each other, you're going to be in the middle of them blaming each other for causing additional damage. Just get an unbiased opinion as to the cause of the smoke and what could have caused the problem.

Also be aware that some people run into problems when they have the oil changed at whichever shop has a sale this week. They all use different brands of oil that have different additives. Because oil fills the many passages in the engine, only about 80 percent of the old oil drains out during an oil change. Some old oil with its additives remains and those additives are sometimes not compatible with the additives in the new oil. In particular, rubber seal conditioners could break down and allow seals to start leaking. Those are going to be slow leaks and they will take days or weeks to develop. That's more common on high-mileage engines and is not going to happen as soon as you leave the shop. Those leaks will be slow and usually are only noticed as spots on the ground where the car was parked.

When you take it to the dealer, don't ask them to replace a certain seal that someone else diagnosed. Let the dealer's mechanic find the leak himself and come up with an estimate for repair. If you tell them which seal was already diagnosed, they may be reluctant to double-check in the hopes of saving you time and cost. Also, if they think it's something else, they might doubt their own diagnosis which is more likely to be right.

If that seal turns out to not solve the problem, they did what you requested, and if there's still a leak, you have to pay for them to start a whole new diagnosis. We've all had egg on our faces after following through on someone else's diagnosis and it turned out to be wrong. Even worse, mechanics, and especially service advisers, (the guys at the write-up desk) really hate it when they find something else wrong after they've given you an estimate. They feel like the more you agree to additional work, they're going to keep "finding" stuff to fix as long as you keep your wallet out. Sometimes additional parts that are needed can't be found until some disassembly is done. Then it's necessary to call you with an updated estimate, but the service advisers really hate doing that. The guys I worked with got very angry with the mechanics for putting them in that position.

It's normal too for them to find other needed work if the car hasn't been in the shop for a while. Even during simple oil changes, I always "read" the tire wear for hints of worn parts or alignment problems. Some steering parts are really easy to check while you're just walking past the car when it's up in the air. I checked every outside light bulb, all exhaust hangers, and I looked for signs of brake fluid and coolant leaks that owners hadn't noticed yet. It's pretty easy to find something legitimate on almost any car, but you have to make a judgement call on how important those items are and whether you can handle them yourself. Reputable mechanics will not be offended if you decline the extra repairs. They would be negligent in their duties if they didn't point those things out.

We called those things "upsell" items. The oil change special gets your car in the shop, but it's the additional things they find that increase their business. A worn tire complaint can turn into two ball joints and an alignment. An oil change can turn into new wiper blades or a new battery, etc. Dealers often lose money on oil changes and other minor services, but they advertise those things to bring you in.

In 25 years, I can only remember about a half dozen cars that had something seriously unsafe and ready to cause a crash, and the owners refused to believe us. I know there were many more people who thanked us for noticing something important before it became serious.

Something else to consider that I would never have pointed out years ago is it is now possible to run into all kinds of new problems from working on your car yourself. I respect anyone who tries to do their own repairs when they're competent, and I especially love helping people who want to learn about their entire car, not just the current problem, but some things that were common in the past cause big problems now. Replacing a battery is one of them. Due to all of the computers on cars today, many of them have to be reprogrammed once their memory is lost when the battery is disconnected or run dead. In my mind, the manufacturer designed the car that way to be sabotaged during a simple, common repair procedure that you know is going to be needed at some point. Volkswagens must be towed to the dealer to unlock the computers. GM vehicles are almost as bad. The only reason to design a car like that is to make money off the owners. Draining and refilling coolant was an easy do-it-yourself project every two years. Now many engines have involved procedures to burp the trapped air out of the system. If that isn't done, the thermostat won't open resulting in overheating and possibly a warped cylinder head. Those types of things are best left to the professionals now. The reason I got on this line of thinking is your comment about them finding more things wrong with your car. You can always come back here for advice on those additional recommendations. Also, if they're busy and have appointments scheduled, they often don't even have the time to do that additional work. They'll offer to set up an appointment for another day. That will give you time to think it over, ask us for advice, and it's easy to cancel the appointment later if you choose.

Hope everything works out at the dealer. It would be nice to hear if they find something simple and inexpensive.