Twinturbo

Firstly, my reference is www.mototuneusa.com .

Apparently in modern engines, when breaking in an engine, hard acceleration and de-accelarion runs should be performed. The honing in the cylinder walls is very fine in modern engines, therefore it wears of quickly. To get maximum sealing from the rings, to achieve the best performance and durability, the engine must be worked hard from new, as the best time is in the first 50 ot so km.

If you think your being harsh with your engine by running ot hard, well at the factory ALL engines are put on an engine dyno and revved up to test if everything is OK. And no this is not bad for the engine.

So to wear in your engine correctly and not by the handbook, once your engine is warmed up, progressively, but quickly do some acceleration runs. De-accelartion runs are also important to suck out the oil and debris from the cylinder walls, and to wear all parts of the piston seals.

If you dont believe me, there is a long and detailed explanation on the link above

Turbo2

There have been ongoing debates (and will continue to be) on how to properly break in an engine. Many engine builders swear by the "drive it like you stole it" break in method, while others believe that you should take it easy for the first 1000 miles. However, if Im buying a new car with a warranty I will follow the recommendations of the company, if something happens during the break in period and they are able to find out that you did not follow the guidelines on engine break in your warranty may be voided.

xtianpel

With all due respect, I would not trust a website where on the first page they show an ad to go see chicks and where the article is written in green, red and yellow.
Another problem I have with the article is that it appears on a motorcycle website, regardless of the fact that the article says this method works in all types of engines.
The writer further states that this method was tried in 300 engines "with no problems whatsoever". I have a hard time believing that 1 of of 300 engines would have "no problems whatsoever", I don't care who makes them.
Anytime I hear "never" or "whatsoever" or extreme words like that a big red flag goes up inside my brain as to the veracity of the facts being stated (remember, this guy wrote a book and is trying to sell it).
I don't believe everything I read and at the same time I don't believe everything I hear or watch on TV. I like to be conservative, so I do change my oil every 5000 miles, not every 10000 like MB says I could, and I did follow MB's recommendation to go easy for the first 1000 miles (as hard as that was because I'm also very impatient!).
Maybe I'm too conservative, but if MB is "wild" enough (in my mind) to have me change my oil every 10000 miles I can't believe they wouldn't take advantage of stating another selling point, which would be "no break-in period for our cars".
I'm sure there's a good reason for it, but this is your car, so you can do as you please.

I submit my opinion to you with utmost respect.

theboogers

the site is for braking in racing engines. they get rebuilt frequently. i would drive the car a little hard up to the 4500 rpm line until 1000 miles. ask the guy who is on his second sl55 engine how he broke his in.

sillydriver

I suspect the break-in period specified by the manufacturer isn’t for the sake of the engine at all (in agreement with the website) but is really there for the transmission and particularly the differential. The gearing in the differential has a complex milled shape which doesn’t have the smoothness of the honed parts in the engine itself. The break-in allows the surfaces of the differential gears to work-harden, allowing them to handle the enormous torque you get on a full throttle launch in first gear. If this theory is correct, then what you might want to do is take it easy in the low gears where torque to the rear end is highest, but floor it early on at high speed in, say, third gear to seat the rings.

Twinturbo

yes, both previous opinions are interesting. Although i dont know about flooring it early on if your view is correct, as peak or a high percentage of torque, depending on model, comes around 2000rpm. Why do you think the mototune method is not durable fo the engines, what parts will it affect in the ENGINE. I am not to familiar with how the diff and gearbox should be treated when new, so i will not disapprove your view, but lloking from the engine side of things, why would the SL55's engine blow up, unless it was cracked or faulty from new?

SL Boy

I recently visited the AMG factory and they confirmed it is not necessary to break the engine in. However the same is not true of the other components.

OKHJOON190

im sure everyone has already heard my story about my second sl55's engine going caput. the more and more i read about breaking in periods the more i beleive this led to the demise of my car. i never properly broke in my vehicle because the dealership said :

"have fun, and check out how fast this car is. no need to let the car even warm up... just drive it, its made to be driven hard right out of the dealership."

i definately now say that you should take it easy on the car for at least 2000 miles before going nuts.

SL Boy

I cannot believe the dealer said this. Do you have it from them in writing? Surely no engine is designed to be driven flat out from cold.

There is a huge difference between breaking an engine in and flooring it from cold.

OKHJOON190

no he didnt put this in writing ... he just said it befor i left the dealership ... honestly i never heard anything about breaking in a car until i came to this forum. now i know better

SL Boy

ok if dealer said this to you its probably his fault not yours

Greg Elmassian

I re-read the mototuneusa site...

Well, I think it's wishful thinking on his part, thinking a particular way of breaking in will make it faster.

The funny parts are his theories about how deceleration sucks the particles from under the piston (past the rings!!!) and into the combustion chamber to get them out of the car. If there was enough clearance for particles, your compression would be very low! (Think about it)

One theory that almost makes sense is the higher speed makes the higher pressure that forces the rings out more to make them break in sooner. Almost makes sense, but I would submit that the small difference in pressure isn't enough to make any difference in how quick the rings break in.

The funniest one is he states/implies that if you don't floor it during breakin, then the cylinders will wear in before the rings seat... pretty funny, since it is the action of one against the other that causes the wear on each. How could you make one wear sooner if it is worn by the action of the other?

Bottom line, the reason that sustained high speeds are avoided in breakin is that since the surfaces are not completely smooth, there can be smaller areas of contact, and this could lead to localized heating which could overheat the ring. (Pretty impossible to overheat the cylinder when the piston is covering the length of the bore!)

Another thing during breakin is that the wearing down of the crosshatch honing (which is pretty smooth nowadays) could leave some small bits of metal in the oil, so changing the oil after 500 miles or 1000 miles certainly could not hurt.

Back in the old days, like 20 years ago, the precision of the manufacture of blocks, pistons, piston rings, was not up to today's tolerances, so old "urban legend" information seems to still be around.

Take it easy for 2k miles, run it up to redline, but drop right back off (that does help draw oil up on the cylinder walls, for lubrication and cooling), avoid sustained high speeds and you are ok.

I used to race myself (motorcycles mostly) and there were always the guys that claimed that breaking in the motor "hard" made it run faster. Never could correlate the claims with actual results.

Greg

Twinturbo

OK, here we go, obviously i have interpreted the information differently to you.

Firstly, decelleration runs suck the particles pf the cylinder walls where the honing is, not from below the piston. And if you think that particles cannot make it through the rings, then how can "oil be drawn up on the cylinder walls"? Also the cylinder honing will wear the rings only on one area if you do not vary your engine speed, which will mean poor ring sealing on the areas necessary when revving hard. The rings need to be worn all over, which can only be done so by hard acceleration and high and low engine runs. I think I've covered most of your crap.