Break-in period?

[X5FX]

Yes, I changed my oil at 3k miles and will do so again at 7500, and every 7500 after that.

Also dont be afraid of WOT after she breaks in...its a blast and is good for the engine.

[GPSnV1]

Having just signed for a 2008 4.8 sport yesterday (pick up Tues), I am worried about the conclusion of this thread.

Why? Because it has 150 miles and will have maybe 400 local miles before I launch a 3K interestate trip during July. And since I have DVTs (blood clots) in my left leg, mr cruise control has been critical to my driving habits.

I have read the manual which gives few details other than something as obvious as varying the speed the first 1,200 miles and not exceeding rpms or mph. Anyway, the advice in this thread to stay away from interstate speeds for the first 1K is troubling since there is no way for me to change my schedule.

Any updated advice for the road ahead of me?

[Fastbuck]

Originally Posted by GPSnV1

Any updated advice for the road ahead of me?

It's not the interstate speeds which are the issues, it's just how interstate driving impacts the requirement to vary speeds. You should be OK if you conciously modify your speed whilst on the interstate and don't hold it steady for a prolonged period.

[vinuneuro]

Originally Posted by Fastbuck

It's not the interstate speeds which are the issues, it's just how interstate driving impacts the requirement to vary speeds. You should be OK if you conciously modify your speed whilst on the interstate and don't hold it steady for a prolonged period.

It is the interstate that's the issue. You can only keep varying the engine speed intentionally so many times over a 3k mile trip; and he also mentioned he'll be using cruise control a lot of the time due to health reasons. If it's a trip that long cross-country type, almost all the highway travel will be very open.

[GPSnV1]

Originally Posted by vinuneuro

It is the interstate that's the issue. You can only keep varying the engine speed intentionally so many times over a 3k mile trip; and he also mentioned he'll be using cruise control a lot of the time due to health reasons. If it's a trip that long cross-country type, almost all the highway travel will be very open.

Good grief, I don't want to ruin this new beautiful creature, not to mention expensive.

In the 2004 4.4 sport, I could hit over 100 between OKC-MEM then parts of MEM to Nashville. However, once at MEM then esp Nashville on to Knoxville and parts of NC, etc., there is a lot more congestion so I can't use cruise as much as I like or drive as fast as I want.

Anyway, in terms of the next 1K, these miles will be mostly on open highway and it would be a real problem to vary speeds and reduce the use of cruise but if that's what it takes then maybe I need to add another hotel stay at least going.

But am I being told to worry about the entire trip? There will be some city driving in between the first half of the trip and then the return home, but maybe not enough to really make a difference in terms of what we are discussing. Do I need to add another hotel on the way back? Does driving a shorter distance on a given day make a difference over going as far as we can tolerate?

[vinuneuro]

If it were my car I'd be doing WOT now. Put it in 2nd or 3rd gear and do WOT, but don't let it shift at the rev limiter. Before you reach that point, get off the gas and engine-break (don't use the axle brakes). Do this as many times as possible before the trip.

Make sure the engine is fully warmed up before you do this.

[GPSnV1]

Originally Posted by vinuneuro

If it were my car I'd be doing WOT now. Put it in 2nd or 3rd gear and do WOT, but don't let it shift at the rev limiter. Before you reach that point, get off the gas and engine-break (don't use the axle brakes). Do this as many times as possible before the trip.

Make sure the engine is fully warmed up before you do this.

A colorful experiment outside my experience. I'll need to give it a shot and see what happens.
Thanks.

[mtech8]

Okay. I can understand why it's important to break-in the engine by varying speeds. But what would happen to the engine if we didn't do this? Will anything break?

Also if we had to drive constant freeway speeds for a while, can't we just extend the break-in period longer prior to exceeding the 4500 rpm and 100 mph to achieve the same affects?

A lot of these concepts are so different from what was instructed to us years ago with older cars. ie: I was always told to let the car idle for about 30 seconds if the car's engine is cold (in the mornings) to let the fuel mix and lubricate, then drive slowly until normal temperature is reached.

I'm just wondering if technology has changed or if I was just doing things wrong previously.

[y5choi]

I bought my x5 500km (that's Edmonton from Drumheller, Alberta for my fellow Albertans or Canadians) away from home and I had to drive home after picking it up of course.. steady 120km/h for three hours. After that, i went to Banff National Park for a weekend and did consistent highway driving for up to 4 horus (up to 160km/h at times. manual reads no higher than that speed during break-in.

So that sums up my first 1000km on the X. During the rest of the break-in period i did city driving almost exclusively. I got an oil change at 2000km even though my servince rep insisted that i didn't need it

right now I'm at 4500km and my gas milage is barely making 21L/100km. thats around 11-12 MPG US.

Maybe the break-in has to do with it??

It's an 07 4.8i

[Penguin]

FWIW, here's something I've posted several places in the past in response to similar questions:

The entire point of break-in is to let the parts themselves do the final "machining" and wear themselves into the best possible fit/mating. As machining technology gets better and better, break-in becomes less important... but final "wear-in" is still important. You want to wear down the high-points (on a microscopic scale) without doing it so fast or long that your generate localized heat which causes a "microweld/micro galling," leaving a micro pit or bump. As such, short bursts toward redline (not under load) actually will help "wear-in" the parts. Short burst of acceleration also help, e.g., accelerate for a couple of seconds and then back off. What hurts during break-in are either sustained running at high speed/load, or running at a constant load/speed for a sustained period of time. With different speeds and loads, different areas (again on a microscopic level), tend to be the "high spots."
Think of it as trying to hone the parts together as you would sharpen a knife, with the varying speeds and loads as moving the knife to different angles, but not wanting to get the knife blade hot.

Understanding what you are trying to do is more important than slavishly following the rules ("Gee, I just hit 1,000 miles so I can nail it!). Think of the first 1,000 miles as being similar to a ten minute "limbering up" prior to exercise... start easy the first few miles and gradually work up to normal running over the first 1,000.

WIll disaster come if you don't do this? Probably not. But doing it will increase the odds that you have a trouble free engine that goes 200,000 miles, vs. one that has a bearing problem at 75,000 - 100,000.


Note: When I talk of hitting redline, I'm talking of a very short burst of the engine while it is not under heavy load, e.g., a throttle "blip" in neutral or during a lightly loaded upshift. The "couple of seconds acceleration" I mention is under load while driving and should not ever be near the redline of the engine while breaking it in.

Some people propose to "break it in hard," suggesting that this gives more power. Well, there is some truth to that... but not in the way many people think. Most engines (if maintained) will actually hit their peak horsepower during their life somewhere around 30,000 to 50,000 miles. This is the point when parts and clearnaces have worn to the point that friction is reduced; however, not to the point where compression or other power-robbing things happen. So, if you break it in hard, yes, you might see a tad more power. But that's because you have shortened the life of the engine considerably with excess wear aging it prematurely.

P.S. for those who say engines nowadays are already "broken-in" as they come from the factory due to more precise machining, I did an oil analysis on my Z4 from new. In the first 2,000 miles there was approximately five times the wear metals as in the second 2,000 miles.