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Do I Really Need to Get My Air Filter and Fluids Replaced, Or Is the Oil Change Guy Full of Shit?

If you ask them, everything needs to be changed

If the modern automobile had a status on Facebook, it would undoubtedly be “It’s complicated.” With their computer-controlled fuel injection systems, continuously variable transmissions and three-phase four-pole AC induction motors, the days when every Dick, John and Harry could wrench on their ride seem long gone.

But you don’t need to be a gearhead to master the basics. In fact, despite cars’ complicated nature, not much has changed when it comes to the simple stuff — and when it comes to Car Knowledge 101, there are no questions too dumb.

I went to get my oil changed, and in the process of getting lubed up, the service tech pulled out my air filter and told me that it needed to be changed. I feel like I just changed it, but I don’t know. Also, like it’s always gonna be dirty, right? That is, how am I supposed to know if it’s this-definitely-needs-to-be-changed dirty (otherwise my car might explode), or just doing its job and showing off the (dusty) fruits of its labor? Same for my other fluids — brake, transmission, etc.
Ahh, I know that feeling. Feels like every time I get my oil changed, the same thing happens to me — you pull in, start getting your shit drained and the next thing you know they’re saying you need to replace basically everything.

Upsell, or genuine concern?

The honest answer is it could be both. Many quick-lube chains incentivize their employees to get you to change more than just your oil, but at the same time, you might really need to get that filter changed. The bottom line is, it’s up to you to know for sure. And that’s where your car’s service manual comes in to play.

Inside the service manual, each manufacturer lists the maintenance that needs to be done at each mileage interval. Many manufacturers will recommend that air filters be changed every 10,000 to 20,000 miles for your first couple, and possibly as often as every 5,000 to 10,000 miles once your car/engine begins to get a little long in the tooth. So if you know how many miles your odometer was clocking the last time you got your air filter replaced, and you’ve checked your car’s service manual for the manufacturer’s recommended replacement schedule, you should have a good idea of whether the person at the quick-lube place is full of shit or not.

Unfortunately, service manuals aren’t always easy to find, or maybe you don’t know exactly how long it’s been since the last time you changed out your filter. No big deal: There are some telltale signs it’s time to swap out that puppy, pronto. Let’s start with the obvious: Does it look like it needs to be changed? If you can get it out (this goofy guy will show you how to remove it), hold your dirty filter up to a light — can you see the light streaming through it? If not, it’s time to replace.

Other more, shall we say, urgent signs your filter needs replacing include a decrease in fuel efficiency, reduced horsepower, or most obviously, a “check engine” light.

As for your fluids, the general rule of thumb is, the darker and murkier, the more likely you need to change them. Brake fluid is typically amber in color, and transmission fluid is typically red; if what you see is dark brown, blackish and/or cloudy, it might be time for a flush. But honestly, you shouldn’t have to change them very often — brake fluid is an every two to three years kind of deal, and if you have an automatic, transmission fluid shouldn’t need to be changed until 50,000 or even 100,000 miles, if at all. To check for yourself, they all have reservoirs or dipsticks; so as you would with your oil, give it a look and see if the color seems off.

Or heck, just take the tech’s word for it.