You may occasionally get ripped off by a mechanic or auto repair shop.

While there are some honest and decent mechanics and repair shops, some take advantage of car owners with high prices, problems not fixed properly or repairs that don’t hold up.

There also are some auto repair shop scams that you need to know about: Knowledge is power.

Some may be innocent and may just be a salesperson trying to make sure your car is extra safe, while others may be simple fraud.

Here are some of the more common rip-off scams and what to watch out for and what you should do:

1. Types of engine oil. Which type of oil does my vehicle take and how do I know that I am being sold the correct type of oil? There are three different types of engine oil. Conventional oil, Synthetic Blend Oil and Full Synthetic Oil. Conventional oil is standard oil. Synthetic Blend oil is a mixture of conventional oil and synthetic oil. Synthetic oil is lubricant consisting of chemical compounds that are artificially made. Each vehicle manufacture recommends a particular type and weight of oil for optimal engine performance. Check your owner’s manual for the oil recommendations and oil change intervals. This will prevent you from spending more than needed, and will prevent you from possibly voiding your engine warranty.
2. Frequency of oil changes. Most oil change shops recommend 3,000 miles for an oil change. However, today’s vehicles have sensors that are designed to measure the viscosity of the engine oil. Engine oil viscosity will change on your driving conditions, long trips versus short trips, traffic conditions that you drive in, short trips but long times of running the engine. The mileage recommendations that you see on your oil change sticker is used as a tool to remind you of your oil needing to be changed. Change the oil based on mileage and NOT on time.
3. Upsells. Most people see this as a way for an automotive repair facility to make extra money. In fact, each vehicle manufacture recommends routine maintenance intervals. How can you be sure that you are not being taken advantage of? Check your maintenance intervals in your owner’s manual. Keep in mind that these are recommendations from the manufacture, different conditions may affect vehicles differently.
4. Air filters. You’re sitting in the waiting room, a service advisor approaches you, shows you a dirty air filter and says this came out of your car. The next step is to sell you an air filter. But how do you know if it really came out of your car? You will need to see your vehicle, so that you can see that the air filter you are seeing is definitely yours.
5. Buying a tire versus flat repair. Not all flat tires need to be replaced. As long as the puncture is not on the side wall, the tire should be able to be repaired. There are different ways to repair a tire. Some automotive repair facilities will use a plug where you do not even have to remove the tire. Others will use a patch on the inside of the tire or a plug and patch combination, if the tire can safely be repaired. Ask your service advisor to show you the damage to your tire, and have them explain completely why a new tire is being recommended versus a repair.
6. Used parts being passed off as new. If you are paying for new parts, you should be receiving new parts. Do not be scared to ask to see the new and/or old parts being installed. Make sure that the parts being installed are Original Manufacture Parts, or OEM parts.
7. Engine Flushes. Engine flushes are designed to break down oil sludge in your engine and also prevent oil sludge from forming. Utilizing engine oil cleaner & conditioner is a proactive approach to avoid engine oil sludge from forming. If an automotive repair facility recommends an engine oil flush due to oil sludge, make them prove it to you. Have them show you the sludge that is causing them to recommend it to you. Normally it can be found on the bottom of your oil cap on the engine. This is a common up sell that is NOT needed.
8. Fuel Injector Cleaning. Cleaning fuel injectors is a service frequently recommended by dealers and repair shops. But unless there are noticeable signs of clogged fuel injectors (such as a rough idle, stalling, poor acceleration or high emissions levels), it might not be necessary. One tipoff is that fuel injector cleaning is not typically listed on automakers’ routine maintenance schedules.

Whatever work you get done on your car, get a written estimate and be sure that no work is done before you approve that it proceeds. In the meantime, go look for a good mechanic who you can trust. It will be a relationship you’ll never regret.

Check the reviews on their website, Google, Facebook, Yelp and NextDoor. Customer reviews go a long way. Go with your gut. If you do not feel comfortable, then get a second opinion.

Get more "car smarts" in my book, "Lauren Fix's Guide to Loving Your Car”

Lauren Fix, The Car Coach® is a nationally recognized automotive expert, media guest, journalist, author, keynote speaker and television host. Post your comments on Twitter: @LaurenFix or on her Facebook Page.