How important is the break in period?
 

My '13 hybrid had 10 miles on it, but I received it with 50 miles as the dealer had to secure it from another dealer's inventory. The manual says for better performance in the long run, avoid going over 55mph and vary the speeds for the first 500 miles. I have about 200 miles on it now and did drive at 65+ on the freeway for 70 miles or so. I haven't braked (is this a word?) aggressively per manual for the first 200 miles. I also obviously avoided full throttle starts as I rarely do that anyways in a big truck.

I will do my best to stay under 55 for the next 300 miles or so but it's not very practical. Ideally I'd like an engine that doesn't burn much oil if any. Varying speeds at 55 and less on the freeway is no fun and not safe. What's the science behind the break in rec or more importantly how critical is it to follow them down to the t? I know about the rings needing to seal etc so I'm looking for better insight that readily available know enough to be dangerous fodder. as u can imagine there will be tens of thousands of owners who aren't nearly as careful as we enthusiasts are with our trucks. Even I forgot about the <55mph rule!

Thanks!

Re: How important is the break in period?
 

just drive it normally, nothing too aggressive, hard braking or fast acceleration, etc. you should be okay and remember to use only mobil 1 synthetic, preferably the extended performance version.

Re: How important is the break in period?
 

Will follow your marching orders gladly. thank u!

Re: How important is the break in period?
 

Evois has it well described but don't change the first oil change before about 1000 easy miles. Factory oil has some extra additives that aftermarket doesn't. And you don't want factory oil all the time either. The main thing is the rear axle. Hard towing early on can cause a nasty gear lube smell and possibly bearing failure later. The main thing is not to do very long steady running early, IE coast-to-coast right off the bat. 15 minutes to half hour steady followed by some long decelerations like coasting off a long down hill exit ramp. You are probably doing everything right from the sounds of it. So enjoy the ride.

Re: How important is the break in period?
 

Thanks HH! I was hoping you'd reply to this thread. I'll change the oil at 1K miles.

Re: How important is the break in period?
 

The reason to vary the speed is to develop a wide wear pattern on gear mating surfaces. That helps to avoid gear noise. Do not set the speed control and let it go for long periods of time before 1,000 miles. If you are going on a long trip, take some county roads at 45 MPH to mix it up with the 55-65 MPH highway speeds.
I would leave the factory fill oil in for 2-3,000 miles to ensure that the rings have seated properly.

Re: How important is the break in period?
 

Shall I change oil with fully Mobil 1 synthetic at 3k per my original plan or just follow the dic?

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Re: How important is the break in period?
 

Split the difference. 4k and go full synthetic.

Re: How important is the break in period?
 

And then moving forward follow the DIC or change every say 5K with fresh?

Re: How important is the break in period?
 

DIC after that is more than fine with synthetic.