There seem to be two camps. I've seen those that advocate stomping on the engine to high revs and backing off in the initial break-in because of some alleged benefit.
Then there's a more traditional school of thought, such as this post:
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Both claim scientific reasons for their method. It seems the "flog the engine" guys say to change the oil soon after an initial run period of say 20 miles to get rid of initial metal particles, the above quoted appears to say those metal particles are beneficial.
Any thoughts? Real world tests of engines broken in one way vs another?
There are no studies offered to back up the claims made in the post.
Such real-world tests, unless done with the proper controls and done with several trials would be anecdotes. The plural of anecdotes is not data.
The best advice would be to follow the break-in procedures recommended by the vehicle manufacturer, the people who know the engines the best, and the people who employ people with real expertise.
Indeed. The manufacturer's engineering staff know what is best for braking in that engine. If you do not trust the manufacturer, why buy his product? If you trust him enough to buy the car, believe the manual.
When in doubt, the procedures in the owners manual take precedence.
That said, I *still* think that you need to be overall gentle on the car for the first 1,000 miles or so, and vary speeds deliberately on the freeway rather than nail the Cruise Control at 70 and stay there. If you need to stand on the gas for accident avoidance feel free, just don't do a drag strip launch at every green light.
And even though they keep insisting it isn't necessary, do the first oil and filter change early, say 1,000 miles. They may not be using straight-30 non-detergent "break in oil" anymore, but the engine is still going to spit out more friction products as the final bedding in process happens.
And don't switch to synthetic oil till you have enough mileage to determine the rings are bedded in and it isn't burning oil - 5,000 miles minimum.
Jeff make some good points. I have never seen any real-world, double-blind studies examining this topic. Common sense would seem to indicate that, with today's close manufacturing tolerances, an extended break-in is unnecessary. But even with close manufacturing tolerances, there are still going to be high and low spots on the cylinder walls, ring diameters, bearing surfaces, etc. that will have to mate in with their corresponding surfaces. This will take time and will result in higher wear products than will show up later in the life of the engine.
All I can do is tell you what I do with a new engine:
I drive it easily for the first 500 miles and very the engine rpm's within reason (I don't lug the engine at low rpm's, neither do I hit red line).
After the first 500 miles, I will run the engine up to red line, at full throttle for brief intervals. I hold it at high rpm for just a moment then ease off to normal engine speed.
I change the oil and filter after about 1000 miles using a name-brand multigrade conventional oil with the weight recommended by the manufacturer.
After the first 1000 miles, I drive normally. The second oil and filter change is at about 3000 miles. The rest are about every 4000 to 5000 miles. I use name-brand, multiweight, conventional oils and name brand filters, no house brand oils or filters for my cars.
This has resulted in engines with will over 100,000 miles that don't use more than a quart of oil between changes. It works for me so I don't see any reason to change.
Automakers generally know a lot more about their engines and how they are manufactured than the people who work in repair shops or write magazine articles and blogs, so IMO, the safest thing to do is to follow the automaker's break-in recommendations. I'm not sure about other automakers, Toyota runs new engines to redline for a while after they are assembled, and then again on a chassis dyno as the cars are coming off of the assembly line.
I don't necessarily follow what I preach, and when got in the 200 ~ 300 new cars I've driven, I just drove them the way I expected to use that particular car, and experienced no engine problems.
One poster said he would accelerate the engine to the redline. I'm clearly no expert, but I've never had the engine in either of my Toyotas within 1500 rpms of the redline, and in fact tend to back off on the accelerator to get the trans to shift into a higher gear as soon as warranted. I've got 140K on the older engine and 55K on the newer one with no problems and they perform perfectly. So I'll leave the redlining to somebody else.
The good thing about modern electronically fuel injected engines is that they have an engine RPM limiter to prevent damage from over-revving. An occasional trip to redline won't hurt the engine, although a steady diet will tend to wear stuff a little more quickly.
That's a good idiot proof measure to keep most of them from over rev damage Ray, but for the few folks that prefer to run the engine to red line and then down shift, they mechanically take the engine way over red line and usually incur engine and at times drive train damage as well using that method. It's only money.
Been there, done that, blown the 2-3 upshift in my Trans Am, fortunately didn't bend any pushrods. (went 2-1 instead of 2-3, didn't get the clutch all the way out before realizing what I had done, but probably overreved it.)
FWIW, the engine still runs fine. The clutch didn't survive the nitrous though.
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