Is it a bad idea to break in a new car by driving it 300 miles home on the freeway? I've heard long highway rides at a constant rpm and speed are not good for a brand new engine.

 

Agree with that statement. Well, that's how I've carried out "my" break-ins.

If freeway driving is a neccessity, then vary your speed constantly. Annoying, but effective. And I don't mean by 5 mph. More like 20 mph+ and shift often if you have an M/T.

The alternative is use your GPS or Google maps and plot a route home using side roads by-passing the freeways.

Good luck and post pics!!!

 

The Owner's Manual only has a line about not accelerating too rapidly or braking too rapidly for the first 600 miles. Why all the comments about varying speeds?

 

Most cars suggest that. I don't think my 2012 Fit did though.

 

Is the engine max revved on a dyno bench before installation? I thought all new cars were but I don't know why I think that.

 

so maybe I just don't get it... but why do you need to "break in" a vehicle at all? Isn't a machine built to run?

 

Mostly has to do with seating piston rings and getting the best seal you can by "breaking it in" properly, letting the parts clean themselves of any casting imperfections, things like that. Changing RPM, letting off throttle in gear, high load acceleration (not necessarily high throttle), all that stuff is supposed to help do that.

Honestly I don't know how much of a difference that stuff will make in modern low tolerance engines... i'm sure Honda builds them to the lowest common denominator and assume the general motoring public will just drive normally and not pay any attention to break in.

I play it safe and still did all that stuff because i'm a car nerd. But I also didn't keep the break in oil until the MM told me it was time to change. IMO 10k miles is too long. Call me conflicted. It's more about the filter than the oil, but that's another story.

Can't go too wrong following the owner's manual though, so just do that.


TL;DR
I wouldn't recommend a constant throttle 300 mile road trip to break the engine in.

 

There is some reason behind it. Its too allow parts to fit in better, specifically the internals of the motor: rings, cylinder wall.............. etc...... Fit better results in long term vehicle performance.

With today's tighter tolerances (thanks to robotics and automated machinery), its not as critical as 3 decades ago but it still will help.

We know we should refrain from red-lining every gear change in a new car, but at the same time, we also want to avoid under-lugging the engine.

AW, has the dealer changed your rear chrome trimming???

 

How can I break it in while bringing it home? It is a manual tranny, so I can vary the gear, speed, and rpms... I hear its good to vary the rpms, including going up to decently high rpms for all distances of piston travel? I can also stop and let the car cool off in the middle of the trip if that helps (a heat cycle?) Thanks yall, i've never broken in a new car before, and would like to do it properly, but the car is about 266 miles away and I'd need to bring it home.

 

You've got the right idea, go with it

No need for "heat-cycling" though. Stop if you need to eat or use the bathroom though that's good.

 

A break-in trip isn't a bad idea, but you want to do it on the blue highways where you will vary speed, use the brakes, etc.

In response to a previous question, engines are not red-iined on a dyno before installation. That would be pretty hard on the rings and bearings. I don't know about Honda specifically, but most manufacturers' engines are spun on a fixture and oil pressure is checked, but the engine isn't run until it is installed in the car.

 

Enjoy your drive home , just your speed some and do not brake really hard and I think you will be just fine. As mentioned these are not the cars of yesteryear and the cars are put through a lot during R&D. Just go easy for the first 600 miles.
Good Luck!

 

What are these "blue highways" you speak of? I've seen you use this term once before, but I'm not familiar with it. I'll be driving on the Interstate

 

Spaceballs is correct!

On page 317 of the 2015 Owner's manual, it says the following -->

"During the first 600 miles (1,000 km) of operation,
avoid sudden acceleration or full throttle operation so
as to not damage the engine or powertrain.

Avoid hard braking for the first 200 miles (300 km).
You should also follow this when the brake pads are
replaced."

 

Whaddaya mean?

Thanks everyone for the explanations!

 

My bad. Was thinking of another FF who had bubbling on her Fit's rear chrome trim. She's from Texas!!!

 

Ohhh, haha. I wish I had a Fit even if the chrome bubbled up. No Fit yet! I'm originally from Texas and female, so you were close!

 

Great 80's novel by William L Moon about traveling the back roads during a rough patch in a marriage.
Easy on the new brakes is a good rule to live by. A hard stop early on will negatively impact the life of new pads forever.

 

I suspect that constant highway driving would be the best way to break in an engine. However, since you are driving a manual transmission, I would avoid most forms of engine braking; I would simply clutch in and use the brakes (within reason and not doing anything unusual that could compromise your safety).

Honda guards against sudden acceleration and heavy braking. As for the brakes, they probably want to make sure your brakes are fully broken in to avoid uneven wear or scoring of the rotors. I wouldn't worry about the brakes too much since they are so cheap to replace and since you have a manual transmission, your brakes should last a very, very long time.

Constantly driving on a flat highway seems to me like an ideal way of running the pistons at a constant speed and allowing the rings and parts to wear in properly and evenly. There's nothing more violent on a car that city use, with constant braking and taking off from stops which wears the clutch.

However, I would be conservative in accelerating on the highway but this really is a no brainer. It's rarely a good idea to gun it until you get to speed, just accelerate normally, shifting at a usually RPM and not running your engine too far up pas 5k rpm and you'll be fine.

I can't comprehend how constantly varying speeds and RPMs would be a better way of braking in an engine rather than running it at a constant RPM.

 

Correct me if I'm wrong, but the theory goes that a new cylinder wall needs to have the piston rings seated properly. This involves full travel of the pistons (varied rpms,including decently high rpms for full travel) and pressure (which means engine braking). A constant rpm would cause more wear at a certain height or level of piston travel in the cylinder, as opposed to variation of rpms. Hard acceleration would also help seat the rings as well. I wouldn't overdo the acceleration, though, but probably just a touch. All this after warming the engine up fully. It seems that city driving would be the best for breaking in an engine, not a highway drone.

edit: just put a down payment on an incoming White LX Manual