Tacky or Techie? The Tachometer.
August 27, 2022
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 Star Lube & Auto Repair

In the Hot Seat (Repair and Maintenance of Seat Heaters)
April 27, 2025
It's chilly outside. You flip on that switch that looks like a picture of a seat with little heat waves rising from it. You expect soon you'll feel that warmth but wait! It's not getting warmer. Oh no, what's wrong with my seat heater? There could be lots of reasons it's not working, and it cou... More

Alleviate the Creaks and Squeaks (Chassis Lubrication)
April 20, 2025
If your vehicle creaks and squeaks when you drive down the road, it may mean that some of the metal parts are rubbing against each other and need to be lubricated. Those could be parts of the suspension, steering system and the drivetrain. Years ago, most vehicles had to have their chassis (wha... More

A Fluid Situation (Check Fluid Levels)
April 13, 2025
There's one fluid in your car you are always careful to keep at a certain level: the fuel. If you don't have fuel, you're not going anywhere. Your vehicle has other fluids which are vitally important to proper and safe operation, too. So, here's a "level" headed approach to those "other" fluids... More