Breaking in a car: is it important?

[Cristatus]

Is it important that when you take delivery of a brand new car that you break the car in by driving slowly, and carefully, or is it ok to start revving the engine high?
And is it 1000 miles in the US, or other imperial measurement countries? Because I believe the garage told us it was 1000 km, which doesn't seem like a lot of miles.

 

[mwmorph]

Break in

as for break in, there are advocates against it, but everyone i've talked to that's got some credibility in the automotive field says you should follow break in procedure, including a engineer at Honda Motors. Now you can see that as some guy covering his ass, but I'd like to believe the guy who designs the cars knows what he's talking about.

 

[Jeff7181]

The engine isn't the only thing that needs to be broken in. Any moving part has a break in period.

 

[cbrsurfr]

Follow the manual and you won't have to think about it...


Here's what the manual for my new GTI says:

For the first 600 miles (1000 km)

- Do not drive faster than 3/4 of the top speed shown on the speedometer.
- Do not use full throttle.
- Avoid high engine speeds.
- Do not tow a trailer.

From 600 to 1000 miles (1000 to 1500 km)

- Speed can be gradually increased to the maximum vehicle speed or maximum permissable engine speed (rpm).

During the first few hours of driving, the engine's internal friction is higher than it will be later when all the moving parts have been broken in.

*For the sake of the environment if the engine is broken in gently, the life of the engine will be increased and its oil consumption reduced.

 

[woodie1]

There are many theories on breaking in a car. You should always avoid making a panic stop if at all possible for the first few hundred miles. As for the motor, once you allow time for the oil to reach normal operating temperature you can drive it how you normally drive except you should avoid constant speeds and wide open throttle for about 1,000km or 621 miles.

 

[jagec]

Whichever breakin theory you follow, all agree that break-in is important, and that you should NOT drone at a fixed speed/RPM for very long (ie freeway driving).

Varying engine loads and engine speeds are important. And don't open 'er up until it's completely warm.

Of course, lots of people report success using all manner of break-in procedures, from the very mild "drive like a grandma until 1000 miles" to "Drive it like you stole it to get the rings seated"...so clearly modern engines aren't horrible picky. Just don't lug it, and don't do any long-distance freeway.

 

[JulesMaximus]

Originally posted by: Cristatus
Is it important that when you take delivery of a brand new car that you break the car in by driving slowly, and carefully, or is it ok to start revving the engine high?
And is it 1000 miles in the US, or other imperial measurement countries? Because I believe the garage told us it was 1000 km, which doesn't seem like a lot of miles.

Read the owner's manual and follow the recommendations in there.

 

[exdeath]

Some say that with a new engine, you should load it up and floor it and take between idle and redline as much as possible in the first 100 miles or so (after it warms up of course, that is never ignored break in or otherwise). This puts the greatest possible pressures on the rings while the crosshatch is still fresh and sharp, allowing a limited window of opportunity for the rings to file themselves to seal against the cylinder walls before the crosshatch fades. Esp. with moly rings.

This is likely where "vary the speed, don't keep it in one place" comes from as in order to rev against a load you have to slow it down first so you can then step on it to bring it back up again. Cruising at one RPM doesn't present a load to the engine like having to climb to that RPM in the first place does, and once you climb up there and can't go any further, all you can do is let it drop then do it again. Hence the 'vary the speed' principle so that you are always climbing the revs and exposing the engine to load as much as possible.