Chevy High Performance Question and Answers - Performance Q&A

Kevin McClelland Jul 26, 2010 0 Comment(s)
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Give Me A Break-In
Q I have a fresh 355ci I assembled myself and it has not been started yet. I've heard two schools of thought concerning engine break-in, (not counting cam and lifters): The old school is to run it mildly for 1,000 miles so you don't glaze the rings, then you can go nuts. The newer theory is to break it in the way you intend to run it. What do you say? Also, at what mileage would you change the break-in oil: 500, 1,000?
Michael Roshon
Pataskala, OH

A Drive it like you stole it! Seriously, components and machine work have come a long way over the years. Back in the day, you needed everything to get real happy with each other before pouring the coals to it. Modern piston rings have been lapped at the factory to speed in break-in. Also, honing techniques and equipment have advanced greatly.

A break-in procedure we've used for years is to find a slight grade or hill in your area and run the car or truck up the grade at first with light throttle loads until you reach the top. Then turn around and, using the engine compression to limit the speed of the vehicle, return to the bottom. What this does is puts load on the rings as you go up the hill and creates heat as they break in. When you then come back down the hill, the engine braking creates high vacuum in the combustion space, drawing oil up to the rings, cooling them down. Next, run up the hill, progressively running the engine harder. Do this several times, stopping after three or four runs and letting the engine cool down. On your final track up the hill, run the engine under about 75 percent throttle. After you have taken the time to break the engine in this way, then change the oil and filter. We like to change the oil after break-in, long before 500 miles. This will get any debris out of the engine that has been shaken loose from the early running and any contaminants from everything getting happy with each other.

Once you have a fresh filter and oil in the engine, run the engine as hard as you wish, within reason. You probably can't run the thing wide open for five miles; however, this should give you a very good idea if everything is OK. We'd certainly have no problem running it right down a dragstrip.

For break-in, make sure you use petroleum-based oil and a high-shear additive like Lucas Engine Break-In Oil Additive, TB Zinc Plus (PN 10063, available at most auto parts stores). This additive replenishes the zinc and phosphorus that have been reduced in our current motor oils. You can also use this as an oil additive to protect flat-tappet camshafts. Source:

Still Going To Burn
Q I am 17 years old and a senior in high school. I recently bought an '06 Monte Carlo SS with a 5.3L V-8 that has displacement on demand and is front-wheel drive. This car had 86,000 miles on it and now has 90,000. Since I bought the Monte it has used oil, about 1 quart per 600 miles. The dealer I bought the car from was in touch with GM and they thought it might be a lifter problem. The dealer replaced the lifters and GM covered half the bill, but it still cost me over $1,000 to repair. The problem now is the engine is still using oil at the same rate. What do you think the problem could be? Thanks. Connor Hiebner Via email

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A We turned to our good friend Ken Casey at Burt Chevy, and he checked all the technical service bulletins related to your car. The only thing reported for your car is a couple of oil leaks at the rear main cover and at the oil pressure sensor. There is nothing about excessive oil consumption like yours. He did state that there has been an issue with roller tappets in the 5.3L truck engines and the dealer may have done you a favor having you replace them.

Back to your oil issue, I'm assuming you don't have the leaks listed above and that you've done accurate consumption measurements. Your engine should be sealed up and have no problem going for 3,000 miles on an oil change without needing to add oil. Not knowing the history on the vehicle before you purchased it, we can only make a few guesses. Luckily, there is no oil path to the intake manifold like on the Gen I and Gen II small-blocks. This leaves the rings and the valveguides/seals as the leak path. If the engine was ever overheated badly in its past, it could have either cooked the valve seals or reduced the tension on the piston rings. Both are very tough to identify. A good technician should be able to see deposits on the spark plug if the intake valve seal is the leak path. When the piston rings are the leak path, the oil comes up around the head of the piston. If it is severe, the oil will make it up to the plug, but in your case the plug lights the mixture burning down to the oil.

We would push back on your dealership and have them help you with diagnosis of the rings or valve seals. These engines have come so far over the years that they run incredibly dry. Oil consumption issues have become things of the past. Hope these few tips will help. Good luck.


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