Driving a Brand New Car Many Miles Home - Doesn't that Break a Break-in Rule?

Every now and then I hear about someone buying a brand new Prius, then driving the thing a hundred miles home or more. Call me straight, call me square or whatever, but in the owner's manual ....

'for the first 600 miles, avoid driving at a constant speed for long periods of time. '

I'm quite sure new engines like varying loads like suburban driving when new. Hitting the highway for a long stretch seems to break one of Toyota's break-in rules.

What say you?

btw, I'm avoiding any long, cruise control type highway stretches for at least 600 mi.

You can always use highway pulse and glide lol

I don't worry about the break in rules. I, do take it easy for the first few hundred miles but I don't stress over it. If you can avoid very long trips then do it. If you can't then don't worry about it. FWIW some of the quickest (drag racing) unmodified cars I have driven were beat on from mile 1.

Cruise control on the Interstate would certainly break this rule. But most regions still have other roads, labeled 'highways' on the state road maps, where slower and variable speeds are quite reasonable.

I bought by car from a dealer 100 miles away. The roads were US highways and not interstates. I was just advised not to use cruise, try to vary my speed as much as possible and not to hold one set speed for too long on the drive home. I was able to do this without any problem and continued to do this up to about 1000 miles to be on the safe side.

Used to be that you weren't supposed to drive faster that 55 for the first 1000 miles too. I wonder how many accidents that caused on the interstate? Anyway, all these break-in rules are BS in light of modern manufacturing, with how tight tolerances are due to emission rules. It's just folklore that is dying away slowly. If anything, setting cruise on a CVT-type car in rolling terrain would give the motor whatever rpm variance workout that it might need.

If break-in truly made any difference, then we'd hear stories all the time across all makes/models how the motor or trans blew up at 10K miles due to lack of adherence to the rules.

That last sentence makes perfect sense now that I have had the car for some time with a ScanGaugeII and have monitored ICE, MG1 and MG2 rpm along rolling terrain. At the time that I bought it I would not have understood that.

Shows again how much the sales people do not understand about the Prius.

I seem to remember varying load on new engine was for proper 'seating' (sp?) of piston rings. Not sure though.

Yes, varying load is an important part of it. High throttle presses the rings harder into the cylinder walls, then light throttle relaxes the load and allows better lubrication.

The other important part is to avoid sustained high loads on the engines.

Gears in the transmission and differential also should be shown a little mercy at first. As good as manufacturing process are these days, there is still a small amount of high initial wear as the parts become better aquainted.

I picked my new 2006 Miata up in Cleveland with 4 miles on it and drove 1157 miles in the next 24 hrs to Florida. Ran perfectly for the next 5 yrs. and oil samples showed less than their normal wear metals readings and encouraged me to extend the oil change intervals (I changed at 5K always and never extended even at their suggestion). Did the same on my Ford Ranger pickup with same results. Didn't do it on the Prius only because I bought it locally, but probably wouldn't have worried about it if I did. Not encouraging anybody else to vary their program, just relating my experience with this subject.

This is a rule I will be breaking when I take delivery of my new Prius Plug in. My first commute in the car will be a trip back home from Carson, California to Fort Worth, TX. Maybe I should spend a few days in California and put 600 miles touring the state.

Newer engines with more advanced materials do not require the break-in periods that older engines needed.

I just found this on the Internet:

You didn't mention what make of car you bought. Having worked for Honda and being associated with the people that write the manuals, I can assure you that frequently, they print errors and old wife's tales. Driving your car at a reasonable constant speed won't hurt it. "Wear in" or "break in" was something extremely important in the earlier days of automobiles when machine tools were not as precise as today. The closer the machine tolerances and the better the finish, the need for allowing the parts to mate one to another through wear decreases. Your rings need to seat, but that can take place at a constant (reasonable) speed. Take your trip and don't worry about it. Remember to change your oil and filter at the specified interval.
Source(s):

Garage Owner

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I will be picking up my Plug-In Prius in Tucson and driving it 1,000 miles home to the Dallas area. I will be driving it at a reasonable speed and not "pushing" it. I'm sure the engine will be fine.

The 2010 Owners manual contains:
" Breaking in your new Toyota
To extend the life of the vehicle, the following precautions are recommended
to observe:
l For the first 200 miles (300 km):
Avoid sudden stops.
l For the first 600 miles (1000 km):
• Do not drive at extremely high speeds.
• Avoid sudden acceleration.
• Do not drive at a constant speed for extended periods."

As stated above in other posts, if you've ever watched a "Scanguage" you will see the engine RPM vary all over the place, even on "level ground" in cruise.

I don't see any problem taking a new car on an extended highway trip. Just keep your speed down a bit (take secondary highways). Oh, and don't drive like an idiot.

My car was driven up from Maryland to find a buyer. For those who want to take the owner's manual as Gospel, what is "extremely high speed"? 55mph? 65mph? 70mph? 88mph?

What is an extended period? 15minutes? 30minutes? 1 hour?

It seems the owner's manual would be better off if Toyota's paragraph was replaced with David's phrase : Don't drive like an idiot.

I don't know who wrote the book but I'm sure it wasn't an engineer. people expect to receive a book with the car. It's cheaper & easier to copy & paste "the old one". It doesn't matter if it refers to things the particular car doesn't have because chances are, few people will read it.

I don't know who wrote the book but I'm sure it wasn't an engineer. people expect to receive a book with the car. It's cheaper & easier to copy & paste "the old one". It doesn't matter if it refers to things the particular car doesn't have because chances are, few people will read it.[/QUOTE]


Ooh! Ooh! Cynical you!

With a CVT it certainly won't matter ... it's like a snowmobile ... go up a hill, down a hill, the RPM's will vary between about 1000 and 2400 constantly ... even on level terrain it varies all over the place. Nothing to worry about.

REV

The FUNNY part is when Pearl was very young I took a secondary highway to Drumheller (see my Avatar). That highway crosses an old river valley about 500 - 1000' deep. It pretty much goes straight down into it and straight up the other side. Pearl reved up to almost 5000 RPM on the way up on cruise, and OMG!!! she only had a few thousand km on the odo. Now turning just 70,000 km. Hasn't blowed up yet!

Yes, a lot of the owner's manual is a cut-and-paste job from previous owner's manuals from all sorts of Toyota vehicles.

Prius engine will do a good job of breaking in itself, just drive it normally. The brakes do need some break in during the first 1K miles or so. Remember we have re-generative braking that stops us most of the time so you should deliberately use the friction brakes, gently but firmly, during those first 1K miles or so.

actually it is not as much seating per se.

Piston rings are designed to rotate under normal conditions (not stuck in burned oil deposits), and driving with constant speed can cut spiral marks in bores and cause excessive blow by. It is not a problem after the rings/bores are seated in and sharp edges are grinded down.

As pointed out before, the engine speed of a Prius is not related to the speed of the car. They are entirely decoupled. In other words, the engine in your Prius can run at any speed it sees fit to best meet current power demands. This means that CC on the highway will not result in steady engine RPMs, unless the highway is perfectly flat, traffic is consistent, and winds don't vary.

I wouldn't worry about it, but I would avoid wide open throttle and panic stops. Take it easy for the first few hundred and all should be good.

Tom