CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

What is the best way to break in an engine?

I was forced into replacing a much beloved car because of unexpected engine trouble. I purchased a Ford Fusion with a 2.4 cylinder engine. There seems to be a lot of differing information about how to break an engine in. I would like to hear how you would break an engine in to make it last. Also, why would they not specify an oil change regimen at 3000K in such a small engine? Will fully synthetic oil improve my chances?

Thank you

Read your owner’s manual. Synthetic oil will not improve your chances since most people extend their oil changes based upon the synthetic oil. If it makes you feel better then do the first oil change at 3000 miles. If not then follow the oil change schedule in your owner’s manual.

Assuming your daily use is “normal driving,” just drive it. You might open the hood and familiarize yourself where to check and add fluids and do so when filling up but otherwise, enjoy.

Your engine is broken in within the first 20 miles. However, you should drive it reasonably for the first 1000 or so anyway.
The reason why car makers refer to 1000 miles break-in periods is because they’re trying to assure that someone doesn’t take that brand new car, beat it into the pavement, and then come back in for a warranty replacement. Each new car is budgeted a certain amount for warranty repairs and one damaged engine will eat that amount up PDQ along with a chunk out of other new cars.

Granted, this can happen anyway but the car makers are just trying to improve the odds a bit.

My feeling is that oil should be changed on a new engine within the first few thousand miles, whether it’s a new car or old car with a new engine.

Engines and lubricants have improved greatly over the years but generations-old advice has not. As stated by OK above, your engine is broken in within a day or two of normal commuting. And it should be all right to follow the manufacturer’s recommendations regarding oil.

No problem if you want to change the oil sooner or use more expensive synthetic oils; do so if it will make you feel better.

And 2.4l is not ‘such a small engine’, it’s pretty much the standard size for mid-sized cars. Also, there’s no relationship between engine size and oil change interval.

I second Rod’s suggestion, and would add to spend some time familiarizing yourself with your oener’s manual and its accompanying recommended maintenance schedule.

Over the past 40++ years I’ve broken in numerous new cars and driven most of them into the hundreds of thousands of miles (338,000 in one case) without ever wearing out an engine, and I’ve done it all by driving the vehicle the same way I alway drive right from day one. Heck, my current vehicle has 179,000 on it and runs like new. I’d probably still have the vehicle with 338,000 miles if it hadn’t gotten hit.

The primary thing to do is to follow the instructions in your owner’s manual.

For what it’s worth, as a general rule, I think they typically say to vary your speed (so avoid the cruise control and try to mix two-lane roads and four-lane highways) and to avoid high RPMs. Also, some makes (such as Honda) use a special break-in oil, so you don’t want to change the oil early on those.

My comment about the “small” engine reflects the feeling that I have that the car as I purchased it is underpowered. It has good pickup but it is not the Buick that I left behind. The 3.8 l 6 would get you out of a serious jam if it needed to- I don’t have the confidence yet in this engine nor have I had to test it. I went for the 4 cylinder for the gas mileage improvement without the hybrid price tag.

Thanks for the comments.

I can understand why you’d be disappointed in the performance having left the 3.8L buick behind for the 2.4 cylinder [sic] engine. How’s the mileage on the new car been?

@NotWiser–I think you made a good choice with the Ford Fusion. The last vehicle I used from my institution’s fleet was a Fusion. I drove it about 120 miles–about 90 miles interstate and 30 in stop and go traffic. I don’t know what engine the Fusion had, but I know it wasn’t the hybrid. if I were in the market for a car, the Fusion would be the first one I would consider.

You’re right, the 2.4 won’t have the torque at low rpms that the 3.8 did. Once it’s broken in you may be pleasantly surprised at the 2.4’s power at higher rpms. I recently switched from a 3.0l v6 to a 2.5l 4, and haven’t had any problems.

There’s another looong discussion on hp vs torque…

Quote from NotWiser: “My comment about the “small” engine reflects the feeling that I have that the car as I purchased it is underpowered. It has good pickup but it is not the Buick that I left behind. The 3.8 l 6 would get you out of a serious jam if it needed to- I don’t have the confidence yet in this engine nor have I had to test it.” Unquote

My wife and I have driven many miles in a 1.6 liter 51 HP VW diesel. She has her own car now but I still drive the diesel once in a while. We live in an urban area and drove much of the time on city streets and urban freeways and found no problem merging into freeway traffic. Neither she nor I hesitate when merging; just step on the pedal and go. Passing in rural areas may require a little planning but it can be managed. What is the serious jam that you speak of?

This post is to simply assure you that your car will have plenty of power.

I had no specific idea of a jam but I have had to punch the pedal to avoid an accident many times. I do lots of highway and rush hour driving. People can be a bit insane on the way to and home from work. I work at avoiding problems on the road- my car works with me.
As for the mileage, time will tell - the dash says I have 380 miles to go until E. I will be astounded if this is true.
Thanks again for the comments.

No need to be astounded, the “Miles to Empty” display on new Fords is pretty close, but a tad pessimistic. I have made it into gas stations with the display reading “1 miles to Empty” and still not put in the full stated capacity of the tank on my Escape. I wanted to put a gas can in the back and drive it until it runs out to see how far is left at “0 Miles to Empty” but I don’t think it’s great for the fuel pump or injection system to run out.

I think the 2.4 l 4 has plenty of punch, even in the Escape which certainly outweighs the Fusion. You just have to let it wind up some.

I had a Fusion with the 2.4 as a rental for a week last year, and it was the only rental car I’ve had that I wasn’t anxious to give back. I drove it about a thousand miles during that week, including a long highway trip. If I remember I averaged 32 mpg (and I’m a “spirited” driver), and the 2.4 was surprisingly peppy.

I think the best way to break in a new “modern” motor on a new car is to drive it normally. Just avoid abuse which is a full flat out floor it start, and running up the rpm over 5000 for the initial 500 miles. After 500 miles you should and can push the motor harder. Watch the oil level with a dipstick check every 2 weeks as new motors might burn a bit more oil as the new parts wear in and seat together.

When to change the oil initially should be covered in the owners manual. If not, I do like an earlier than normal oil change for the 1st one. One exception is Honda. Honda recommends against an early oil change as they use a specific factory filled oil for the break in. Follow Honda recommendations as per their owner’s manual.

Thank you all for the comments - There seems to be a lot of expertise accessible here. I appreciate this greatly.

Am I the only one that knows that the Fusion never had a 2.4L engine available for it? The current model has 2.5L I4 and the first gen model had a 2.3L I4. But never a 2.4L.

But to answer your question. There’s not much breaking-in to do on a modern engine. Just vary the vehicle and engine speed during the first 1000 miles or so, and that’s it. Most of the break in is done in the first two dozen miles.

Look at the owner’s manual to make sure that synthetic is not required. If not, I’d just use regular oil of the proper viscosity (likely 5W-20 or 5W-30) and change it and the oil filter every 4,000-5,000 miles. This works very well for me. Just don’t do anything goofy, like putting 20W-50 in it. Modern engines aren’t made for that heavy stuff. Others on these pages would disagree, but I’ve never seen any advantage to using synthetics in normal conditions, and I know a couple people who have messed their engines up doing the synthetic oil/extended change interval thing.