10 things your car mechanic won't tell you

An oil change is to a skilled mechanic what making brunch omelettes is to a talented chef — something of an insult. That said, oil changes are the most common maintenance need for cars. You can buy an oil-change kit at an auto parts store for less than $40, while having a mechanic do it will run you around $75 (yes, I know some shops are much cheaper, but I don't think you should expect a mechanic to do the dirty work effectively for free just to keep your business).

Oil changes are easy money for repair shops and dealers, so not only will they steer you toward them, they'll endorse the "every 3,000 miles" standard, even though modern oil can last much longer, with some synthetics requiring a change ever 10,000-20,000 miles.

You CAN stick to the tighter schedule — and to be honest, fastidious oil changes in certain cars can help with resale value down the road, as some buyers want records to fussy prior ownership.

However, in my book, if you don't mind getting dirty and having to deal with disposing of the used oil, an oil change twice a year is the classic DIY option.

The check engine light strikes fear in the hearts of inexperienced owners, but it usually just indicates a non-serious problem with the vehicle's exhaust system.

In many cases, you can ignore it, unless you have a very old car whose emission components could be wearing out.

You can't ignore it forever; a trip to mechanic is warranted at some point. But you car isn't going to blow up if you wait.

There is one exception to this guideline: if the check engine light is flashing, you need to get to your mechanic as soon as possible.

Once you start changing your own oil, you might think about doing your own brake jobs. This is one that mechanics often don't like talking about, because changing brake pads and rotors for them is like printing money. It's easy to do, but it takes while, so the labor costs bring in serious coin.

You can do it yourself, but it's both tricky and dirty — not to mention a bit exhausting if you don't have a repair-shop hydraulic lift. Using a jack, it will consumer several hours, and that's if you don't encounter any problems and are dealing only with swapping worn brake pads.

Do it once, however, and you might do it yourself forever.

This is less about the mechanic and more about the body shop. Ever been to a good body shop? While car repair joints can be classic grease pits, body shops are often temples of organization and tidiness. That's because simply walking in the door usually cost $1,000.

I once owned a Mazda Miata that had an acceptable dent that I decided to have a body shop deal with, and it wound up costing me around $1,200. All my other cars have seen me fix the dents and touch-up the scratches and scuffs.

You don't get professional-grade work, but the results are OK. And if you're still unhappy, your mechanic will be happy to refer you to a body shop.

The truth is that there are times when a new car is the best choice. You want three to five trouble-free years, you desire the lastest technology, or you simply have the resources to follow a dream.

Not that much is apt to go wrong with a new car, and if something does, the dealer will usually fix it under warranty.

Seasoned mechanics hate this because they want you to buy a good used car and employ them to repair it. Part of this is business, for sure, but there's also tradesman's pride at work: an old car that you develop a relationship with is simply better.

See slide number 5. The ultimate achievement for a TRUE mechanic is getting your car to vintage status, with a few hundred thousands miles on the odometer and paint that looks new. Any mechanic worth their salt will tell you to drive your car until the wheels fall off — which they won't as long as you keep them in business.

This is more my thing, but I distrust mechanics who think it's acceptable to jake up cars with aftermarket details, such as spoilers, weird wheels, and exotic paint jobs.

BUT all this stuff is easy for a mechanic to add, so most are unlikely to discourage your tackier inclinations.

Infotainment might not excite somebody who turns a wrench for a living. Additionally, the software side of in-dash system is typically handled by the dealership, with support from the manufacturer.

Some mechanics offer services in this area. But the bulk of mechanics are focused on what's under the hood, not behind a screen.

Professional mechanics aren't fans of improvised repairs. Into this category would go anything involving duct tape, for example.

That's because mechanics always have the right tools for the job, while car owners are lucky to have one or two tools that are specifically intended for auto repair. Mechanics have invested in those large, red, rolling tool cases that you always see at the garage. They're filled with tools. And those tools are meant to be used.

A good mechanic does the work as estimated and never overcharges unless they find something serious while doing the agreed-upon repair and update you.

This is the opposite of the dealership service center, where a moderate amount of upselling is to be expected (feel free to decline it most of the time, unless the agent tells you can't have your car back until they fix the problem).

A mechanic who's adhering to the profession's code would rather drop an engine block on their foot than subject a customer to surprise sticker shock.