Using the lower gears on an automatic transmission

My car has a continuously variable automatic transmission. Is it OK to shift to lower gears on a daily basis while traveling downhill? I drive downhill to work, which results in a lot of brake wear.

I have been told by a good friend (who may or may not be credible in this arena, I don’t know) that using the lower gear settings could damage my engine, and should be used sparingly. Is he right?

Also bonus question: how about for driving on snow? Going down- or uphill in snow is very nerve-wracking. Wondering if this would help.

IANAMechanic, but AFAIK engine braking going downhill and hauling things uphill are really the only reasons you have low gear settings at all.

ETA: In older cars, locking the transmission in a low gear could damage the engine if it reaches too high RPM, but most modern automatic transmissions will shift up to prevent any damage.

I have used my lower gears in mountains for years and have never had a trans fail, just don’t forget and leave it in low gear once you get back to highway speeds as your trans can heat up. No comment on snow driving I live in Ca.

Most recent vehicles will not allow you to over speed your engine. Either by not allowing a gear change that would do so, or automatically changing up when required. There are probably some sports models that won’t do this, but my Ford pu and my Subaru Forester work this way. Your dealer or owners manual may have additional information.

Unless it’s the kind of downhill driving that could cause potential brake failure (ie long downhill mountain road) I would always use the brake over the transmission. Brakes are so much easier and cheaper to repiar than transmissions. If I had to choose a place to put the extra wear, I’d do it on the brakes.

My variable transmission hybrid’s owner’s manual said to only use the low gear specifically for downhills only. You wouldn’t have brake wear issues going up hills anyway.

Yes, it’s a good thing to reduce wear on your brakes but more importantly to avoid brakes overheating to the point of failure. Saving brake wear is a bonus.

Could? Sure. Will? Unlikely. There are controls as others have said to avoid hurting your car.

Using engine braking instead of brakes in snowy conditions is safer since you are less likely to lock up the tires and skid. When starting in snowy conditions you want less torque to avoid spinning your wheels so you should stay in higher gears. Most Automatics don’t really give you enough control for that but check your owner’s manual; some have a “winter mode”.

What great information, thanks guys! I’ll have to practice using it now.

They won’t lock up, but, engine-braking torque may cause them to break loose and spin more slowly than the road is going by. Once that happens, a flustered driver may not remember to upshift (or shift into neutral) to let the wheels regain static traction.

Likewise, most cars sold over the past couple of decades are equipped with ABS, which means the brakes are considerably less likely to lock up the wheels than the transmission is.

As for engine/transmission wear during engine braking…it’s infinitesimal. Less than you get when powering forward. Brakes, OTOH, are guaranteed to wear when you use them; that’s how they work.

Going down a long, steep hill in good weather? feel free to downshift and let the driveline keep your speed from getting out of hand; your brakes will thank you.

I’ve been engine braking for the past week because my rear brakes are near-shot, but I can’t get an appointment with my mechanic until Monday. Luckily, I have an Acura automatic transmission that allows me to manually shift through all 5 gears.

My method is to not downshift until the engine speed is below 2000 RPM, although with a red line close to 8000 I’m sure I’m just being a bit over cautious.

My experience engine braking on snowy/slippery roads is exactly as Machine Elf has described: if your momentum is too great for the lower gear you will definitely lose traction until the vehicle slows down.

In my experience using downshifting vs. braking in the snow isn’t an either/or question and there is an element of knowing your vehicle and its gears relative to your speed. What you want is to use a combination of the two to control and slow the vehicle. So if I’m coming up to a stop light and the roads are snowy and slippery I won’t just rely on the brakes, but I won’t just slam it into a lower gear, either. If you’re, say, at the high end of 4th, you don’t just want to drop it to 3rd or you might run into the problem described by Machine Elf. I’d instead let off the accelerator and maybe lightly brake until I feel I’m at a point where I can downshift safely and then continue that pattern until I’m stopped. Your plan to practice is a good one.

Consider this: worn brakes are a readily replaceable, economical item. Worn transmissions and engines are not.

I will select a lower gear if creeping down a hill at a slow pace. I’ll also use a lower gear if pulling something up a steep hill. That’s about it.

Back in the day of drum brakes, brake fad was a real issue. Using engine braking was better than losing the brakes from fade. With disk brakes, this isn’t much of a worry anymore.

Brake fade is not merely an issue with the past - I had to replace rotors after a long downhill ride. And I thought I was babying the brakes. Down-shifting on long downhills in the snow was practically essential with rear wheel drive; with front wheel drive its likely to lead to skidding and loss of control, on slippery roads.

I do a lot of mountain driving her ein Ca and seldom ever touch my brakes, I shift gears all the time, been driving for 50 years and put a lot of miles on my cars. I have never had a trans problem in my life with any car. If you forget to take you car out of a lower gear and start cruising at highway speeds you may overheat the transmission but it will take a while. Using the gears is safer and more economical.

How exactly do you think engine braking is going to cause more wear on your transmission? I mean, I guess there’s some sort infinitesimal amount of extra wear from the transmission and engine parts spinning around a little faster, but it’s not like your brakes where there’s a pretty direct relationship between how much you use them and how fast they wear out.

Even if there isn’t much risk of outright brake failure, using your brakes too much on a long downgrade will wear down your brakes really fast. I’d be astounded if the extra drivetrain wear from engine braking was even measurable.

It’s not the transmission that gets extra wear from engine braking - it’s the engine itself.

BTW, if your transmission is anything like the one in my 2001 Prius, the “low” setting is not actually a low gear. The Prius drivetrain is designed to freewheel when coasting, in order to save energy (you want to avoid turning kinetic energy to heat). The transmission has a “B” setting where the “L” setting would be on a conventional car. The “B” setting is brake mode - it causes the drivetrain to use both regenerative braking and engine braking when coasting. It doesn’t put the transmission into a “low” range - I don’t know what that would be with a continuously variable transmission.

Well, again, I would expect that the extra engine wear from running an already warmed up engine at a few extra RPMs coming down a hill is basically nil.

That wear ain’t much to write home about. You get far more engine wear cranking out 30-50 horsepower when cruising on flat terrain (or 100+ horsepower when churning uphill) than you do during engine braking. Making power? The engine rings are being forced outward against the cylinder bores by hot combustion products. Engine braking? There’s a substantial vacuum during the intake stroke and most of the compression stroke, very light pressures/low temperatures during the power stroke, and nothing worth mentioning during the exhaust stroke. The engine just doesn’t wear much at all during engine braking.

I guess that is one thing… I had an old truck that would smoke and burn oil (faster than usual) when I did a lot of engine braking. On that old thing, I might have wound up ahead using the brakes instead of the engine by virtue of spending less on top off oil.