I've been wondering this for a while. The manual (as well as any car manual I've seen) talks about a break-in period of the first "x" miles (1000 in the case of the F150). It says to avoid towing, and avoid aggressive driving during this time. Now, I don't know anyone who doesn't test drive a new vehicle and want to know what it's capable of during the test drive. Many vehicles go on multiple aggressive test drives before the break-in period is over, and in some cases, vehicles leave dealer lots with 500+ hard miles from during the break-in period.

When I took delivery of my ordered truck, I paid close attention to the break in procedure and made sure to drive it lightly for the first 1000 miles, and I would assume this would be common practice for others who ordered their trucks. But does it really make a difference?

I've been unable to find any studies documenting anything like this, and I'm curious if any of you guys have ever found information regarding this. What I have read seems to emphasize the importance of break-in, but I've never seen any hard data showing the results.

I have talked with a former Ford engineer that says there is a definite correlation between the amount of time a vehicle spends on the dealer lot and how many warranty claims it receives, and that he would advise avoiding any vehicle that's been on a lot for much more than a few months--perhaps for the subject reason.

 

It's true, we called it Lot Rot.

Having known about Lot Rot, I still bought a brand new 2005 Ford Five Hundred in October, 2006. It had been sitting on the dealer's lot for over a year. It only had 23 miles on it when I got it.

We had that car for just over two years and 30,000 miles. We never had anything go wrong with it, and it was still flawless when it was totaled in a wreck.

 

Ouch! That's early the game to lose a new car! I hope everyone made it out okay!

So if lot rot is primarily due to my aforementioned speculations, perhaps your Five Hundred was somewhat immune due to the lack of many test-drive miles. I know I would feel better about buying a lot-squatter that had 23 miles on it than one with over 500 like some of the 2015 F150s I had looked at. Although I suppose the clientele would be something to consider in that equation as well. I wouldn't be as nervous about an aging Buick LaCrosse on a new lot as, say a Mustang.

 

Anything with more than 200 miles can't be sold as a new car. That's a used car and should cost quite a bit less.

 

I've never seen anything either, but it is an interesting question. I see car salesmen beating the crap out of lot cars all the time. They don't care about break-in periods, or even letting a car get warmed up before whipping it to the nearest coffee shop. I'd be leery of any lot car with more than 100 miles. I've never floored a car during a test drive, but I'm sure many do.

When I ordered my truck, I specifically told my salesman to make sure it wasn't driven by the "general population" when it arrived. He gave me a knowing look and replied "Yeah, I know places to hide vechicles". Ironically, he took it for a spin. Liked it so much bought one a few weeks later.

 

I really don't believe that break-in matters that much.

I don't imagine the majority of vehicles get a careful break-in period when they're sold new, and it's downright rare to hear of engine failures in modern vehicles. With the expense of replacing a modern engine I can see engine manufacturers taking steps to ensure that the engine is broken in before it ever leaves the plant.

I paid close attention to break-in on my first few new vehicles, but in the last decade I haven't even given it much of a thought. I've never killed an engine before, either, and with the exception of my '00 Excursion I've never had an oil burner.

 

Well my experience with many new vehicles is it don't matter. Just lately I owned a 2011 F150 cc with 5.0. No issues with it my son bought it from in 2013 and it now has over 100K. I ordered a 2013 F150 cc with 5.0. It was identical to the 2011. I had a exhaust valve go bad and replaced the left head under warranty. Later with 70K and lifters went bad. Replaced under extended warranty. Both truck I bought new and was the only one driving it during the break in.

 

With the exception of piston rings, your engine is wearing out from the very first start. Piston rings need to be broken in by putting the engine under load which raises the cylinder pressures. Bearings etc do not break in.
Automatic Transmissions (Mark can add to this or comment) will experience higher temperatures when they are first run in under medium to light loading and will tend to run hotter than normal and possibly overheat if used for towing in the first few hundred miles.
Differential gears do wear-in and in most cases, the factory backlash tolerance is tighter than the service spec by a very small amount. There are various wear-in procedures for differentials. As far as I am aware, most if not all manufacturers no longer require a 5 or 6,000 mile service for differential lubricants. One truck I owned (bowitie) in 2002 required the differential lubricant to be changed after 500 miles before it could be used for towing.
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All that said - I don't think I would worry much about a vehicle that had been test driven - even test driven hard.

 

You've obviously never been to an automotive assembly plant. Pretty much every vehicle has been floored before it ever leaves the plant.

No, they are not. They each have a minute or two on a final test stand before they leave the engine plant, but they are not broken in. A lot of development has gone into reducing the need for break in.

I've never observed this. I've towed at max GCWR (F-550 - 30,000 pounds) through the Rockies with a brand new trans and didn't have any heat issues. I don't know what would cause more heat in a new trans.


Me, either.

 

Depending on programming and how firm the shifts are - you will always generate more heat with softer shifts when towing. The clutch plates and disc surfaces may be lapped to a finer tolerance than they were back in the 3 and 4 speed auto days..

 

Break it in the way you intend to use it. I break them in pretty hard and have never had an oil burner on a new bought vehicle.

As far as ordering. The last truck I ordered was my former '08 F250 V10. Delivered spanking new in May of '07 with 3 miles. The A/C went out at 2k miles, catalytic converters went out at 56k miles, the front end got the shakes at 80k miles and it went through two six disc head units. I also had a drivabilty reflash at 25k miles.

Current truck was bought of the lot with 30 or so miles and was in stock for a month. Zero issues.

 

My 2011 truck sat for six months and had about 60 miles on it, no issues and I'm just over 70K miles.

However, if this really was an issue, how would the car rental fleets survive? They get a vehicle in and rent it as soon as possible and we all know how those vehicles get treated right from jump.

I was told by the man who replaced the engine in 1988 F-150 to break it in the way I intend to drive it. I put over 100K miles on that reman engine without incident.

 

I know a couple of guys who are into racing, and they swear by the "hard" break-in for their race cars and personal daily drivers. Myself, I have never worried about it, but I usually purchase used anyway.

 

Yea, I doubt that hot shot driver pulling a goose neck trailer with that brand new F450 is going to waste 1000 miles of fuel to break it in.

And I know law enforcement does not worry about break in miles.

Although I've always felt that Ford does something with the programming to limit RPM and torque for the first few miles.

 

Bad assumption....... As long as a vehicle hasn't been titled, it is sold "new" regardless of miles or age. Not uncommon for vehicles to arrive at a dealership from the factory with 50, 60, 80 miles on them if they are pulled for QC. It doesn't take much for dealer traded vehicles to get over 200 miles on them prior to being sold.