Tacky or Techie? The Tachometer.
October 5, 2025
There's a gauge that many vehicles have that says RPM on it. And there are a lot of people who either don't pay any attention to it or don't even know what it is. Here's why it's a good gauge to know about.
It's called a tachometer, and that "RPM" label means it is measuring how many revolutions per minute (RPM) the engine is turning. Automotive experts know that a vehicle's engine can be damaged if it turns too fast (revving too high) or too slowly ("lugging" the engine).
A tachometer (sometimes called a tach) is almost a "must-have" gauge for vehicles with a manual transmission; the driver has to manually change gears; the tach helps the driver know when revolutions are in the optimal range.
Some say you don't need a tachometer if you drive a vehicle with an automatic transmission. It's true that most drivers of automatics don't even look at it. But there are times when paying attention to the tach can help you prevent an expensive repair.
Here's a good example. Manufacturers now build many of their automatic transmission vehicles with shift paddles. They let you shift gears without a clutch. That's manual shifting, and drivers need to know they're not revving the engine too high. That's where the tachometer comes in, since it shows you visually when you are in the red zone (RPM too high).
Here's another way the tach can help you: fuel economy. Generally speaking, the lower the RPM, the better the fuel economy. It's not good to go too low, of course, and the tachometer will help you find that spot of maximum efficiency.
You can also spot problems by paying attention to the tach. When your vehicle stays in first gear longer than usual (higher reading on the tach), then the RPM dip lower than usual after shifting, it may be that your vehicle's transmission is skipping a gear. Plus, if your vehicle's RPM go up but your speed doesn't, it could mean your transmission is slipping. Either situation should be checked by a trained technician.
If your commute takes you down some long grades, you might like to put your vehicle in a lower gear to help slow down the car (and not burn up the brakes). Having a tachometer keeps tabs on when your engine is revving too high.
So, consider the tachometer a "bonus" gauge. It's one more helpful assistant that can help you spot and prevent problems in your vehicle.
Need Service?
More articles from Charlie's Fast Lube Dexter

It's Brake Time (Brake Calipers)
November 9, 2025
Race car drivers have demonstrated the advantages of disc brakes, so most modern vehicles use them. Sometimes just the front wheels have disc brakes, but many vehicles now have them all the way around. A major component of the disc brake is called a caliper. It works by squeezing brake pads ag... More

Tracking True in Dexter: Wheel Alignment
November 2, 2025
At Charlie's Fast Lube Dexter, we occasionally see severe tire damage that could have been prevented with proper wheel alignment. During a Charlie's Fast Lube Dexter alignment service, your vehicle is put on an alignment rack where the tires, steering and suspension parts are inspected for probl... More

Do you have a Clue (Get the Most Out of a Service Visit)
October 27, 2025
When you head to the doctor, you probably have it in your mind what you're going to say about why you don't feel good. That way your doctor can use that information to diagnose your problem. You might want to think of that same approach when you take your vehicle in for a repair. Experts say wha... More
