A website recommends hard acceleration and deceleration for the first 20 miles followed buy an oil change. The reason give is "that gas pressure from hard acceleration forces the rings to contact the cylinder around their entire circumference, which is the only way the rings can properly wear into the exact shape of the cylinder to seal the combustion pressure."

It also claims that if you follow the factory's break-in recommendation, you can lose 2-10% power.

Is this how you would break-in your new Challenger?

The website address is:

http://www.mototuneusa.com/break_in_secrets.htm

 

I don't know about other break in procedures on other cars..but for mine with 400hp

According to the manual of my car....it is stated not to exceed 55 mph for the first 500 miles. The car had 26 miles on it when I purchased it. I drove mine home 90 mins when i picked it up. I hit speeds of 75 mph not knowing anything about this break in. The sales manager never told me about it. I did not beat it, nor did I get on it, smoke the tires or anything of that nature. I drove it sensible and with great restraint. I now have 21K. I burn no oil between 5K oil changes. I get 25-27 MPG on turnpike and straight freeway driving 65-70mph. I get 18-21 round town and occasional bypass driving. I generally refuel at 1/2 tank and alternate 92 and 89 octane. If the 92 octane at refill is a few cents more than 89 I will use the 92(many times I have seen a 12 cent difference in octane). Manual says it recommends high grade gas. Key word being recommends. It further states 89 octane will not harm the engine but you may experience a slight loss of power at take off. I have not noticed any loss of power. No knocking or anything.

I have read other posts of guys who did not adhere to the 500 mile break in procedure and some burn 1 quart of oil at 3K intervals some burn more. Some get 17-19 mpg at best. Some guys just cannot resist or wait for the games to begin.

IMO I think if you take a new motor out and baby it for the first few hundred miles rings and such should seat properly.
I have been fortunate enough to have had 5 new cars and exercised restraint at break in and I have never had a car burn oil or valve taps or piston slaps or any other problem associated with improper break in. I think the key is drive sensible and take it easy.

Incidentally my first oil change was at 2K. It's all synthetic Mobil 1.

 

All new cars run a knock sensor. You will not hear it unless it is extreme. The car senses knock and the computor retards the timing. That is why you can't feel the loss of power, but you are losing some power through the loss of timing. Run the good stuff and you will get all 400 of those ponies. Run the lower octane and you will lose horsepower, but you will not hear it or feel it. Some newer engines are running in excess of 10:1 compression and for that you will need 91 or better gas for the max horsepower output.

 

I agree........ I know about the knock sensors. The compression is 10:1. Some guys tried using 87 octane and had all kinds of knocking... [sm=badidea.gif] At minimum I have a 50-50 mix of 92 and 89 octane. Most of the time though its at 92. I drive conservatively with it and I have no problems accelerating when I need to. My wife tells me I don't drive fast enough. She says once we get the Challenger she will start amassing speeding tickets. This I gotta see.

 

I must agree with the Judge on break in. The only exception is I change my oil after the first 500 then 1000 miles and every 3000 miles there after..

 

I do what the manual says to do. One good reason, if something happens, they can't dispute warranty claims with "You didn't break it in properly"

I change every 6 months or 5000 miles. With the technology of the new oils these days, it isn't like the old days of chaging every 3 months or 3000 miles.