Engine Break In Period

You seem to think it might be a big deal. Why did you buy the car with 85 miles on it?

In all likelihood it is probably fine. Modern engines are designed to very tight tolerances and most samples will be fine even if you start flooring it right at 0 miles. Its always nice to have piece of mind that your engine was broken in properly, but you shouldn't buy a car with 85 miles on it if that is a big deal to you.

 

It's not a big deal.

 

If you are at all concerned, just do an early first oil change and a transmission fluid drain/refill at 30k miles. Both are a good idea in a Prius.

JeffD

 

Not a big deal. You just don't want to power accelerate for extended periods of time, or sustained high speeds.

 

read this Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

 

Not that article again.

On every car forum I've participated in, that article is posted multiple times in threads regarding break in procedures. Along with the one on bedding-in new brakes...

 

Greetings and welcome!
:welcome:
Don't worry about it!

Loooooooong and very bloody wars have been fought over engine break-in strategies...and 99.44-percent of the "stuff you read about" is bunk.
Most modern automobiles, even abused ones, don't go the automotive after-life as a result of engine failure. Usually what happens is a failure of several ancillary systems that combine to make a car too expensive to repair WRT its real world value.

Even if the car dealer put your Prius on a race track for 85 miles, it's not going to alter the trajectory of it's life cycle in any measureable way. Besides.....if you're like most Americans, you're going to illuminate the "change owner" light before the car gets to 150,000 miles anyway....and it'll hold together that long even if you drive it like you stole it.

Enjoy your new car and don't worry about the first 85 miles---really.

 

Motoman's dyno break-in procedure is not all that far from what some engine OEMs were using in house as far back as the 1970s, probably well before that. His street break-in procedure is an adaption of that. For the general population though, his instructions are risky. It's too easy to overdo it.

His instructions give power application cycles for high performance motorcycles that result in high power applications of a very few seconds at a time, then backing off the throttle. If you copy his procedures in a relatively low performance car (like a Prius), you will be on the throttle a lot longer and that is bad for a new engine.

I think the main reason car manufacturers give such conservative break-in procedures is that the average driver isn't well enough atuned to vehicles to follow an agressive break-in without an unacceptably high risk of engine damage. The manufacturers break-in procdure is a little less than optimal but it's safe for even the dullest driver to follow.

One of my first gigs as a new mechanical engineer involved running dynos in a military vehicle manufacturers development shop. As a gearhead I was rather shocked at the break-in instructions we received from the engine manufacturers, but they weren't all that different from what Motoman.

I've also been in two manufacturing facilities where vehicles are randomly pulled of the end of the assembly line and given some full throttle blasts on a dyno. But, the full throttle blasts were only a few seconds each.

 

The break-in period isn't just for the benefit of the engine--lots of other parts need to be broken in (trans, diff, tires, brakes, etc.).

For example, Porsche also has a recommended break in period, even though they stress test each engine on a bench as part of the hand assembly process, prior to it being installed in a car.

 

I don't think you really have to worry considering the prius engine redlines at like 4,500RPM or something, it's not really spinning that fast to cause any friction damage that those ranges.

 

+ It also shares bottom end parts with the Corolla which has a 6400 rpm redline. The crankshaft is identical, right down to the part number.

 

I had a brand new Hyundai Excel in 1993. That car had a break in period of 500 miles.

Every new car I've bought since then, and I've bought 5 of them Prius included has never had a break in period. Now maybe Prius does but if it did it would be in the owners manual. I have not read that cover to cover, but I think I would have spotted it if it was required.

 

^From page 151 of the 2010 Prius Owner's Manual:

 

I test drove my car with 5 miles on it. The salesman, in the front passenger seat, pushed the power button while I was driving. I immediately hit Eco.

That said, I have had the best luck with newer used cars I had no idea how they were broken in. I'd Just forget about it and enjoy!!

 

A couple of things to remember about the Prius. There is no clutch, torque converter, or transmission. (you read that right ... NO TRANSMISSION) The gas engine is connected to the electric motors and the differential through a planetary gearset ... and they are all connected 100% of the time. The gas pedal is drive by wire ... there is no mechanical connection. And, the motors are all controlled by a computer.

You can NOT over rev the motor. You can NOT race the motor. The computer won't let you. Breaking in a Prius engine is not the same as a car with a transmission where you can redline the motor while in low gear. The computer treats a motor with no miles the same as a motor with 50,000 miles. It starts when needed and stops when not needed.

The ECO mode gives you only part of the electric power available and 11% of throttle on the ICE. PWR mode gives you more electric power and more throttle.

Try a little experiment. Put your Prius in D, put your left foot on the brakes, and floor the throttle. No, you won't burn out the transmission ... there isn't one ... and the gas engine will only run up to about 2400 RPM.

If you wan't to know just about everything there is to know about the Prius, go here. John's Stuff - Toyota Prius and more

 

The only concern would be the break-in particles in oil.
First oil change filter was alot dirtier then on consequent changes.
Still nearly not dirty enough to worry about bypass valve opening, not in unless it is sub-0F.

 

In the manual, it recommends you to:

* Do not drive at extremely high speeds
* Do not drive at a constant speed for extended periods.

both for the first 600 miles. Now on to my question,
What is extremely high speeds, and what is extended periods?
I'm planning on taking my brand new Prius on my vacation, and the drive is about 300 miles (about 480 km) long. The roads down there have speeds ranging from 50 to 70 mph (about 80 to 110 kph).

I'm expecting two or three stops along the road to rest, change drivers etc, but no longer than 10-15 minutes each time.

I guess that 70 mph probably isn't in the "extreme" high speed category, but what about 3 hours on the highway in low traffic doing 70 mph? What exactly is an extended amount of time?

 

^Anything over 10 minutes...and it depends on individual interpretation, but try to stay at 60 or below for those first 600 miles.