I guess nearly everyone has gone to a local talyer for routine preventive maintenance service (PMS), expecting to save, but only to drive away after paying a lot more in backgrounds and correctional work. I’m not saying that this is usually the case with most of our local neighborhood car shops. I would want to believe that most shop owners and mechanics are honest, hardworking people who only want to help. But some do take advantage of our ignorance…
Here are some common signs that the shop owner or mechanic is trying to rip you off your PMS:
1) When he tells you to buy his own brand of oil…because he claims that any oil will do.
Some mechanics will tell you that your car can use any kind of oil, especially if it will save you money. There is only a little bit of truth to this. Let's take a very common oil, 5w-30, as an example. The first number is the viscosity, or the ability of the oil to flow, at 0 deg C. The second number is the viscosity at normal operating temperature of most vehicles.
Some vehicles in extremely cold climates use a thinner oil, such as 0w-30, in order to start easier in the extreme cold. Notice the second number, the viscosity at normal operating temperate, is the same as our previous example. Many vehicles can run on this thinner oil in order to get better efficiency in the minutes after starting and is kind of irrelevant in our tropical climate. But that second number, the 'hot' number, isn't one to mess with. Using a thicker or thinner oil than recommended for normal operating temperatures can result in damage to your vehicle. So in this case, not all oils are the same.
This is the same for ordinary mineral oil versus semi-synthetic and synthetic oil. Each of which has different properties and a number of pros and cons. Synthetic oil is more expensive, but can also be better for your vehicle. Some turbocharged and high-performance vehicles even require synthetic oil in order to perform properly.
So don’t get fooled by mechanics telling you an ordinary diesel oil is okay for your gasoline engine. Read your car’s manual.
2) When he tells you to change to closer periodic maintenance intervals. Before you agree to any maintenance, check the maintenance schedule in your car's manual. This maintenance schedule is the only schedule you should be following unless some kind of oil contamination necessitatesflushing and replacement.
Shady shops try to convince you that the vehicle's manufacturer just sets the limit and anything before that is always a good idea. They might even go as far as telling you that they have seen vehicles just like yours that did not have the service performed early and broke down. But this is all a ploy to get you to spend more money more frequently. The manufacturer has done years of rigorous testing in all sorts of conditions to develop your maintenance schedule. They've even tested the vehicles in the coldest arctic weather and the driest and hottest desert conditions in order to find things that fail in order to fix them before manufacturing even begins.
Small shops may do this, but many dealerships also use this trick to upsell. It’s best to refer to the car’s manual.
3) When he tells you, you should replace the entire assembly. Sometimes you need to replace the entire part assembly when something is wrong. But other times, just a simple repair is required. Like for example, a busted airconditioning auxiliary fan. Some mechanics would prefer to let the owner buy an assembly as it is easier to install as compared to just buying an electric motor for it which entails more work. The only way to avoid these things is to ask for a cheaper alternative, or better yet, get a second opinion.