Should I trust Alpha oil level light?

Ray Magliozzi
Ray Magliozzi

Dear Car Talk:

My 2019 Alfa, with a 2-liter engine, doesn’t have a dipstick to check the oil level. Can I trust the oil level light on the dash? Thank you. — Luke

RAY: You don’t have much choice, Luke. Unless you have a gastroenterologist in the family who doesn’t mind getting his colonoscope oily. I’m a bit old-fashioned, and I like having a dipstick, too. But it’s going the way of the roll-down window.

Most people are only too happy to never have to open the hood of their car, so carmakers are responding accordingly. In fact, if you do open the hood now just to look at your engine, you can’t even see it anymore. It’s covered by a big piece of plastic called the “engine cover.” They might as well emboss it with “Nothing to see here, folks!”

The oil level on your car, Luke, and on most new cars these days, is measured electronically, with a sensor inside the crank case. And it is reliable. Put it this way: If you ran out of oil in the next few years and didn’t know it, Alfa would owe you a very expensive engine. So THEY trust the sensor enough to protect their financial interests.

If the level gets too low, the sensor triggers an “oil level” light on your dashboard and tells you to add a quart. They usually build in sufficient leeway so that when the light comes on, it’s not a dire emergency.

Unless it’s pouring out the bottom of the engine (in which case other warning lights will soon join that oil level light), you have time to mosey to a gas station or a Walmart and buy a quart of oil. And on some cars, including your Alfa, Luke, you can even perform an oil level test on your touch screen. And you don’t even have to be able to read Italian.

If you burrow into your screen menus, you’ll find one that says “Car Status.” In there, you’ll see an option for “Oil Level.” Park the car on a level surface, follow the prompts, wait a couple of minutes while the sensor reads your oil level, and — Che Bellezza! — you’ll see a graphic representation of your dipstick on the screen. And if you miss the part of the experience where you burn the tips of your fingers touching the hot dipstick, you can always touch the car’s cigarette lighter.

What pushes brake pads away?

Dear Car Talk:

What moves the brake pads away from the brake rotor when you remove your foot from the brake pedal? — Jaime

RAY: Not much, Jaime.

First of all, when brakes are working properly, the difference between the brake pads when they’re “away” from the disc rotor and when they’re touching the disc rotor is a few thousandths of an inch. That’s thinner than a Kate Moss (that’s the mechanical engineering term, I think). So the pads don’t have to move much either way.

When you step on the brake pedal, hydraulic fluid applies hundreds of pounds of pressure to the brake caliper pistons. Then, each piston moves the pads on that particular wheel toward the disc rotor. There’s a seal around each caliper piston that keeps the fluid from leaking out. And that seal has a sort of physical memory, and when you stop applying pressure, the seal naturally wants to go back to its original shape — and take the caliper piston a few thousandths of an inch with it.

I suspect that the vibrations involved — going over bumps, engine vibrations, any slight warp in the disc rotor — also contribute to pushing the pads back from the rotors. And as I say, they don’t have to go far. In fact, if they were more than a few thousandths of an inch away from the disc rotors, when you stepped on the brake pedal, it would sink to the floor.

That’s why whenever we do brake work on the car, after we put everything back together, we have to return the calipers to their proper position, just a few whiskers away from the rotors.

And we do that by getting in the car and stepping on the brake pedal. The first time we step on it after a brake job, the pedal goes to the floor, but the fluid pushes the piston a little closer to the rotors. When we step again, the pedal goes maybe 80% of the way to the floor, and the pads get closer. Eventually, after five or six pumps, the pads make contact, and that’s when we know it’s OK to give the car back to the customer.

Before we figured that out, we lost a couple of garage doors and a soda machine as customers were driving out of the shop after brake jobs.

Got a question about cars? Write to Car Talk write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.

In Other News