Those nuts didn’t tighten my lug nuts!

Dear Car Talk:

Is it possible for lug nuts to loosen over a period of time (after 2,500 miles) if they were improperly installed? I had seasonal tires changed at a service location, and about a month later, six lug nuts were missing (four on the right rear and two on the left rear). The service center is stating that it is unlikely that they are responsible. However, I am hearing and reading otherwise from other sources. – Barbara

RAY: Oh, it’s very likely that they are responsible. Someone forgot to tighten your lug nuts or didn’t tighten them enough. And that’s exactly what will happen.

Over time, they’ll slowly work their way loose. Every time you hit a pothole or a bump, they’ll get a little looser. Until finally, one falls off. Of course, you won’t notice that. Then, a few days or a week later, another one falls off. Eventually (if you’re lucky), the car will start shaking, and the wheel will make banging noises as it wobbles around. That’s when you check and find out you were one lug nut away from a major accident.

Normally, when we install tires, we’ll start by tightening the lug nuts in a crisscross pattern. Then we’ll go around once clockwise to make sure they’re all tight. It’s a simple job, really. It’s something shops do many times a day. But doing it wrong can be deadly; it’s important to have safety systems in place so no one drives out of your shop with loose lug nuts. That’s Auto Mechanics 101.

Who knows what happened in the shop that day? Maybe the mechanic’s battery powered wrench was low on power? Maybe the roach coach arrived, and he had a sudden urge for a tofu burrito and forgot which wheels he’d already tightened.

In any case, I’d let this shop know that, having spoken to other mechanics, you are quite certain they neglected to tighten your lug nuts properly, and it created a very dangerous situation for you. Tell them you hope they will be putting better systems in place with their employees to ensure it doesn’t happen again.

In the meantime, let them know that someone else will be tightening your nuts from now on, Barbara.

His Subaru Forester is burning the midnight oil

Dear Car Talk:

Can you help me identify what is causing a burning oil smell in my car?

We drive a 2011 Subaru Forester X. The engine is leaking oil, and we think it’s dripping down on a sensor, which is causing lights to turn on on the dashboard. How can we fix this? – Mitch

RAY: You can fix it by pulling out your credit card, putting a pleading look on your face and handing the card to your mechanic, Mitch.

In our experience, the most common oil leaks on low-to-moderate mileage Foresters come from the valve cover gaskets. The oil leaks down from there onto the front exhaust pipe, which gets very hot. The instant a drop of oil hits that exhaust pipe, it starts to burn, and produces a very strong smell.

That smell wafts into the nearby fresh air vent at the bottom of your windshield, and from there, right into the passenger compartment and up your nostrils, where it causes you to feel lightheaded and seek out brochures for 2019 Subarus. It doesn’t take much oil at all to make a lot of smell. A drop or two will do it.

Replacing the valve cover gaskets is not a big deal. It’ll cost you a couple of hundred bucks at most. Unfortunately, the higher your mileage, the greater the chance that it’s something much worse: the cylinder head gaskets. To replace those gaskets, you have to remove the engine. That’s a job that’ll cost you over $1,000. Maybe way over.

So, a test is in order. We start by cleaning the whole area because it’s always an oil-soaked mess. Then we insert a fluorescent dye into the oil. After running the car for a few hours, we shine a black light on the areas that we suspect are leaking. That usually tells us exactly where the leak is coming from.

If you’re lucky, and you’ve lived a good, clean life, it’ll be a valve gasket or two. I’ve never seen so much oil leak that it shorted out a sensor. So, if you’ve got dashboard lights coming on, those may be unrelated to the oil leak.

Start by figuring out what’s leaking. Then your mechanic can scan the computer and figure out which sensor needs to be replaced.

Once you have the full picture of what it’s going to cost to bring this Forester back up to snuff, you can make an informed decision about whether to fix it or grab those 2019 brochures. Good luck, Mitch.

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