Is engine braking (downshifting) bad for your vehicle?

Maintenance/Repairs
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1

I have a 2005 Cadillac STS V6 with about 130K miles that’s a lot of fun to drive. It has an automatic transmission, but I like to drive it in ‘sport’ mode where you push the gear selector to the right and then can control when the car shifts by pushing the lever forward to upshift or pulling the lever backward to downshift. Many times, I will downshift to slow the vehicle rather than use the brakes.

Recently, I have had a couple of issues with the vehicle and I’m wondering if they might be due to driving the vehicle in the manner described above:

1 - Extreme tire wear on the rear wheels. I put a new set of tires on about a year ago. When I went to install winter tires, I noticed that both front tires look brand new with plenty of tread depth left while both rear tires are worn nearly to the wear indicators.

2 - I have to add about one-half to one quart of engine oil every couple of weeks. The car does not blow white smoke out of the tailpipe, and I don’t know if this amount of oil consumption is normal for a vehicle of this age and mileage, but it seems a little high to me. I also don’t know where all of this oil could be going. By comparison, I hardly ever have to add oil to my wife’s 2006 Mitsubishi Endeavor (Although it should be noted that she doesn’t drive as aggressively as I do). cough UNDERSTATEMENT cough.

I’d like to know if downshifting to slow the vehicle rather than using the brakes could be causing the two issues described above. Also is doing this bad for the vahicle in general?

I would really appreciate your thoughts on this whenever you wake up from your nap. Or if you’re too busy to answer this, maybe you could pass it off to one of your lackeys…

2

Downshifting an automatic may cause some accelerated wear of the internal clutches. Brakes are far cheaper to replace, since the only way to replace the transmission clutches is to fully rebuild the transmission.

Using the transmission in this way is putting strain and additional wear on the transmission. The transmission will operate at it’s optimum performance in Automatic Drive. Especially if you drive as aggressively as you state. The driving style probably has a lot more to do with you’re tire wear than the method of shifting. To even out the tire wear, you should have the tires rotated and balanced every 5,000 miles. Many tire stores offer this as part of a tire installation package that also includes free flat repairs.

3

How many miles per quart of oil?

4

Well…I run into this question from time to time… I firmly believe that the IQ of the offenders predominantly hovers around 70 or below.

Unless you are driving an 18 wheeler that is CAREENING down a mountain pass…and smell your own brakes burning…THERE IS NO RATIONALE TO DOWNSHIFTING AN AUTOMOBILE IN ORDER TO SLOW IT DOWN UNDER NORMAL DRIVING CONDITIONS.

The reasons are so many I wont attempt to list them all. The entire conversation is a waste of time and oxygen as a matter of fact. ALMOST ANY vehicle made after say 1980 or so has brakes powerful enough to slow not only the vehicle itself but also one or two vehicles behind it…

To downshift your vehicle to scrub speed ( on a regular basis and not in a dire emergency) is not only harming almost every component in your drivetrain, but also spreading Horrific driving patterns on to a rather suseptible and naive new crop of drivers…

Forgive me for my rather harsh assesment of this driving technique, but I’d rather nip this in the bud so to speak before other people ask the same question…yet again. Lets KILL this HORRIBLE rumor before it spreads further.

Blackbird

5

Since it seems like you love your “sport” mode, that’s most likely the major source of these problems. Downshifting the transmission won’t hurt it too much, but it won’t help it, either. Brakes are a lot cheaper than a transmission, I’d suggest you start using them instead.

Using the transmission like this really should be confined to steep declines where you’d burn up your brakes keeping the car slowed to a reasonable speed…and there are not that many of them around.

Hmmm…maybe downshifting it the way you do will hurt it a lot. If you’ve already gone through a set of tires in about a year, I’d say your rear end is spending a lot of time with the wheels spinning…either in forward, reverse, or while slowing. Neither of those conditions is ideal. However, if you’re willing to repair it constantly, put new tires on it once a year, and feed it oil like most would feed it fuel, have fun. It’s your car, after all. Just put a nice big note in the dash for the next unsuspecting buyer. “Thoroughly thrashed vehicle - buy as a very last resort”

6

Driving in sport mode probably isn’t harmful to the transmission for upshifting–it’s not like the thing doesn’t have to upshift anyway. It may even be slightly better for the transmission since the ‘manual’ shifts are likely firmer than the automatic ones, which will save on the clutch material. Though the higher RPM shifts may be harder on the U-joints, differential, etc. But downshifting all the time is likely increasing wear. And since you’re driving in sport mode all the time, the engine is holding higher RPMs than it normally would, wasting gas and probably contributing to your oil consumption. The downshifting is probably contributing to your tire wear as well, since the rear wheels are doing all of the stopping when you do so.

So I wouldn’t downshift all the time, I’d consider rotating your tires more often, and to help with the oil consumption, consider switching to a different brand and/or a full synthetic oil. I’d recommend Valvoline Synpower or Mobil1. Since you’re harder on your engine than most people, this will also have the benefit of protecting it better.

7

Ugh…I think we are all in agreement here. This practice basically DOUBLES the normal wear on your vehicle.

Think about what happens in a manual shift vehicle…Not only do you use the clutch to move the car forward…which stresses the U joints and all other drivetrain components in one direction…THEN you need to use the clutch and ALL of its components again…(Thats 2X at least) in order to engage a lower gear and stress the parts in the other direction…etc…ad nauseum.

Just please dont do this… I care about mechanical things…lol…I do… You are hurting yours Its almost akin to coming across a guy beating a nice Porsche with a sledgehammer…I’d try to stop him if I could…SaVvy? Maybe I’d get flattened by the sledge tho… LOL… But you get me…

Blackbird

8

Disregarding transmission and clutch wear, if iI remember correctly, both Continental and Lycoming strongly warn against operating their engines at a high rpm/low manifold pressure condition, such as happens when you make a steep descent using the windmilling prop to brake the plane. Their claim is that the low cylinder pressure allows the inertia of the pistons to unseat the piston rings causing ring flutter, something that can lead to broken piston rings after a while.
I personally don’t believe in either free revving an engine at high rpm or allowing the load to rev the engine at high rpm.
It definitely doesn’t do your engine any good.

9

First, I want to thank everyone for their informative and heartfelt responses. I can tell from the spirited responses that you all know your stuff and really care about cars - that’s why I posted my question here.

I want to clarify a few things about the driving conditions that the vehicle is driven under, my driving style and how I maintain my vehicles:
1 - I drive this vehicle 35 miles each way to work every day under mostly highway conditions.
2 - I only drive aggressively and shift the car the way I described in my original post when I’m alone in the vehicle, so I’m not passing my bad driving habits on to any other driver.
3 - I’m hard on my vehicles, but I take good care of them. I do as much of the maintenance myself as I can and I do it when it needs to be done. This includes oil changes, fluid level checks, filter changes, tire pressure checks and rotation and brake jobs. If there’s maintenance that needs to be done that I can’t do myself, I take it to a shop. Basically, I don’t defer maintenance on any vehicle that I own.

In regards to the tires that wore out in a year, I was running the Continental ExtremeContact DWS that I bought online from the Tire Rack. I did my research online and bought these tires since they were billed as an Ultra High Performance All-Season tire. After seeing my excessive wear, I went back to the Tire Rack web site and found other users that reported wear problems with these tires. Here are three quotes from the Tire Rack web site written by people who also purchased these tires:

From April 17, 2011: “12,000 miles and tire is down to thread wear indicator! Stay away from this tire!”

From November 09, 2011: “These tires are wearing poorly and really noisy. I checked with my mechanic to see if my car was out of alinement and he said no, the tires are just wearing badly. One of them is really loud. My mechanic always gets tires from Tire Rack and he says these are the worst he as seen. Now after 12,000 miles I am buying new tires. Definitely not Continental.”

From December 14, 2011: “Do not buy these tires! We are authorized installers and have had to remove more for vibration and failing Road Force in the last year than all tires combined in 20 years. I have been through 9 on my car, and have MANY unhappy customers. We have even requested Tire Rack to stop shipping these to us.”

Don’t get me wrong - these tires get a lot of good reviews. That’s why I initially bought them. However; you can search online to find other drivers who have had fast wear out with this tire. Maybe there are just a small number of drivers out there who drive as bad as I do. Maybe these tires just shouldn’t be billed as “Ultra High Performance All-Season tires”. In my opinion, an Ultra High Performance All-Season tire should be able to handle some spirited driving.

Finally, I never stated that I shift the vehicle this way to avoid putting wear on the brakes. I’m also not that worried about gas mileage.

I never understood the logic of people who buy a vehicle and then don’t want to drive it because they “don’t want to put too many miles on it”. I also don’t get why someone would purchase a high performance vehicle and then drive it so gingerly because they “don’t want to put too much stress on some component or other”. Automobiles are made to be driven. High performance automobiles are made to be driven hard.

Every choice we make as drivers has a cost. If I choose to drive in a more spirited fashion than another driver, then that means that I’m willing to accept the costs associated with that decision (more fuel, oil, brakes, tires, etc.) and I’m OK with that.

I drive the way I do because I have a lot of fun doing it.

I figure you only live once, so if you have to drive 70 miles a day to get to your boring, grey cubicle you might as well have some fun doing it…

Now I have to go schedule that IQ test…LOL…

10

LOL…we should all schedule an IQ test… My results are in… 138 the first time when I was 20 or so… and recently this year…146, not bad I guess… certainly not Einstein but I don’t need to be that bright… I don’t really know what the IQ test even means…I think its the ability to reason or such… SO I can reason well…yet I will give my last dime to a homeless person and then starve all week…real bright…

I agree with you about people who are afraid to drive their cars…I’m not one of them… Its just wanton abuse that I have an issue with…but to each his own. I drive my cycles hard but also take care of them…I don’t abuse them, but use them properly…same with my cars. Its almost akin to using the clutch or grinding the gears… I’m a clutch man…

11

In tire nomenclature, “ultra-high performance” means “ultra-short tread life”

That holds true for cars, too…By now, the car is 7 years old and has accumulated considerable mileage, hard mileage I would suspect, so you must be getting tired of it by now, the short-star motor nearing the end of it’s useful life…Time to pick up a subscription to Car & Driver and start fantasizing about your next road-toy which will hopefully deliver more even tire wear…A CTS-V would more than meet your driving needs…

12

I assume the STS Cadillac the OP drives is RWD. Aggressive driving will put alot more wear on the rear tires if rapid acceleration and deceleration are common. The front tires will wear more on the edges if there is a lot of hard cornering too.

Your best bet is to rotate these tires more frequently to balance the wear. You could also just replace the rears when the winter tires come off and then rotate more frequently. I’m not a fan of Continental tires, so run them out and switch brands. Toyo seems to give good service and decent tread life, kind of like a less expensive Michelin IMO.

13

Caddyman,

You’re right on the mark.

I have been looking and the CTS-V is high on the list. My second choice is the Jaguar XF-R - both of which are way out of my price range at the moment. Maybe Santa will leave one of them in my driveway next week…LOL…

I’ve been Googling CTS-V vs. Jaguar XF-R a lot lately. There are a lot of videos out there showing these cars squaring off, but in my opinion, the V is the winner…In any case, I think that I could get into some REAL trouble with either of these cars.

So I think I’ll keep dreaming and keep driving the '05 STS until it finally gives up the ghost. As I said - it’s been a great car so far and I still have a lot of fun every time I drive it.

Again, I want to thank everyone for taking the time to share their thoughts and insights.

I hope everyone has a safe and happy holiday season.

14

First I’d like to say that in my experience driving my dad’s STS, I find the sport mode useless. My own car has a 6-speed stick, but I think the STS does more than well enough on it’s own. Engine braking is a silly thing to do on most modern cars. An STS has more than enough brakes to slow the car down repeatedly without overheating, especially if you don’t over-use the brakes, which brings me to my final thought on this matter. A skilled driver can drive fast…Very fast!..without abusing the car much. Yes, it will be harder on the car than driving a little easier, and people really shouldn’t drive that fast on public roads. I remember watching a race where they showed passenger seat views of the drivers. Most of them were hacking at the wheel like crazy and grabbing gears like they were $100 bills. The guy that won the race (one of the elder Unsers) looked like an old man driving his grandchildren to school. All the cars in the race were identical.

15

UncleTurbo,

Thanks for the post.

You’re right - it is RWD.

I like your advice on the tires too and I think I am done with Conti’s…

16

My I.Q. is that of room temperature measured in Celcius, but here is my suggestion. Try driving your Cadillac non-aggessively for a month. Don’t downshift and see if your oil mileage improves. When you downshift, you create a higher vacuum and are probably sucking oil in around the valve guides. If you really enjoy downshifting, you can purchase the parts for a manual shift kit that you can easily install from WalMart. Go to the plumbing section of the store and purchase a short handle plumber’s plunger. Go to the automotive section and select a gearshift knob. Affix the knob to the opposite end of the handle of the plunger from the suction cup. Attach the suction cup of the plunger to the floor of your Cadillac by pushing down on the gearshift knob. You are now ready to downshift (and upshift) as you drive. This will save wear on the transmission.

17

Mmmm The CTS-V…isn’t that the 550Hp monster of a Caddy? Now that looks fun…even the wagon with the same engine.

18

You said it, Blackbird.

CTS-V coupe base model = 556 Hp, 0 - 60 in 4.0 seconds…

Like I said — I could get into some REAL trouble with that kind of muscle. (drooling…)

19

YES

20

Aw YEAH I think we could all find ways to get into “trouble” with that many Ponies…and a shapely body to boot. I have ALWAYS wanted to sample the CTS-V… I have driven almost EVERYTHING else…

I was a Bell Boy/Valet in San Diego in another life…when I was 20yrs old… That’s when I could say that I have driven them all…nowadays…not so much. My GOD the things we would do with those cars…Ever see Ferris Bueller’s day Off? LOL…

No, I’m joking, but we DID have to move vehicles from one lot to another rather often when the hotels lot was full…the lots were about 5 blocks apart and I did A LOT of Dreaming in those few blocks let me tell you.

It was the Bristol Court Hotel…I will NEVER forget that place…the top floor had a ballroom…and when you threw a switch…the ENTIRE ROOF would roll back…like a big convertible. That place has to still be around…it was rather famous…Oh the things we did there…LOL… I met quite a few celebs there…and partied with more than a few of them…There were more things that I CANNOT mention than things that I can that went on there… The items and services that would get requested for room service in the wee hours…Aw man…I’m surely getting old… I was nutz as a youngster

Blackbird