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Did I do irreperable damage to my new car?

Greetings Car Talk community!

I am the proud owner of a brand-new 2010 Subaru Impreza Outback Sport. This is the first car I have ever owned and I love it so far – although I am nervous about how I handled the vehicle for the first 1000 miles and how this will affect future performance.

I purchased the vehicle on Thursday, June 25. Immediately following, I took the car on a road-trip vacation with my gf and drove about 1500 miles in the following ten days. The car performed beautifully.

When I returned home, I finally got around to reading the Owner’s Manual from cover to cover and was alarmed to read the following in the ‘NEW VEHICLE BREAK-IN DRIVING - THE FIRST 1000 MILES’ section:

“Do not drive at one constant engine or vehicle speed or a long time, either fast or slow.”

Well, I basically did the exact opposite of this! The vast majority of those first 1500 miles were spent going 65mph (w/ cruise control engaged) on the Interstate Highways to and from upstate NY.

I am curious as to 1) why maintaining a constant speed in the first 1000 miles is a bad idea; and 2) what damage I potentially did to my car and how it could affect its longevity since I purchased the car planning on a 200k+ mile lifespan.

I have put on about 300 miles since returning from the road trip and the car is running like a dream.

Any and all comments are greatly appreciated!


I noticed a typo in quoting the Owner’s Manual. For clarity, the manual instructed: “Do not drive at one constant engine or vehicle speed FOR a long time, either fast or slow.”

If you did this, the piston rings didn’t seat properly. And this can result in the engine burning oil at a later time.


I assume you stopped for lunch, stopped to go to the restroom, stopped for gas.

Hey, I’ve had a number of vehicles over the last 40 years including my current one that were broken in primarily on the highway. And none of them ever suffered any ill effects. I had an '89 Toyota that I broke in commuting 103 miles each way for the first year of its life, 95% of that on the highway. That engine was still running well when the truck got hit and totalled 17 years later at 338,000 miles. At that mileage it still wasn’t burning excessive oil.

I don’t advocate ignoring the owners’ manual, but based on my own long experience I feel the likelyhood of your having created a problem by breaking the vehicle in this way is extremely miniscule.

Enjoy your new ride, sleep well, and congratualtions on having read the owners’ manual. Far too many do not.

Owners manuals have said this since the 1940’s…I think it’s urban legend stuff. Tens of thousands of rental cars are treated the exact same way you treated yours with no ill effects…Modern engines don’t care…

Irreparable damage?? NOT! (disregarding for a moment the fact that it’s a Subaru)…

My current car’s owner’s manual recommends:

For the first 600 miles

  • Not using full throttle (funny considering it is FI diesel)
  • Do not go faster than 3/4 of the maximum on the speedometer.

That’s all she wrote.

My feeling is that your car will be fine. Truth be known, the engine is pretty much broken in within the first 25 miles. The other 975 is pretty much fluff from the car makers who are trying to make double sure they’re off the hook breakin-wise.

Just monitor the oil level over the next 1000 miles and see what happens.

Many new crate engines and some makes of new cars are run up on a dyno at full throttle before even being sold to anyone. I think Harley Davidson runs every new motorcycle they produce on a dyno before shipping it from the factory.

Thanks for the great responses – I can definitely sleep better at night. Btw, I’m absolutely LOVING the new ride!