Break-in

[Sven59]

Be careful, the car records what you do!

[1MtnGoat]

Originally Posted by htron50

Isn't the rear axle liquid sharing the cooler with the tranny and use the same fluid?

If so, do you therefore replace tranny fluid and rear axle fluid simultaneously?
IE, is it a simultaneous event?

The rear diff cooler circulates tranny fluid through it to cool the diff fluid (oil) the two fluids are different. ATF and Gear Lube.

[adamgl]

Originally Posted by Sven59

Be careful violating the break-in period, I believe that the Chevy Service department can tell if you violated some of their rules and could void your warranty.

They're not going to void your warranty for going 6000 rpm in the first 1500 miles. Go easy and vary speed for 50 - 200 miles then break it in hard if you want the max potential from you motor.
Just don't abuse it.

Really, has any 5th gen not went over 4,000 rpm for the first 1500 miles?

[Erik@Torq]

Originally Posted by Sven59

Be careful violating the break-in period, I believe that the Chevy Service department can tell if you violated some of their rules and could void your warranty.

The service department will be well aware of it when my wife lays 20ft of rubber leaving the lot

If the break in period was mandatory and not recommended, they would do like certain German cars and also Italian exotics, they set the rev limiter to 4k and it is removed after the 1st service.

Ferrari takes every single car they buid to there own road course for 5 laps, change the oil and deliver the car.

/Erik

[JMAN311]

I don't believe in babying the car during the break-in period.

My 2010 SS was on the dyno w/ 500 miles on it 369RWHP in stock form

[Mr. Wyndham]

Originally Posted by htron50

Isn't the rear axle liquid sharing the cooler with the tranny and use the same fluid?

If so, do you therefore replace tranny fluid and rear axle fluid simultaneously?
IE, is it a simultaneous event?

Transmission fluid only acts as a coolant medium - the lubricating fluids aren't shared. There is a heat exchanger within the diff housing.

[htron50]

Originally Posted by Dragoneye

Transmission fluid only acts as a coolant medium - the lubricating fluids aren't shared. There is a heat exchanger within the diff housing.

OK! Thanks! That clears it up! I can change the rear axle oil independently.
Then the tranny fluid separately. Got it! I intend to change each at around 800 miles. Will also put in Magnetic Oil/FLuid plugs wherever possible.

[Russell James]

Originally Posted by ZL1_Alkindi

The break in period for cars nowadays isn't as important as it used to be in the past due to improvements in material selection and manufacturing processes... I will probably go easy for the first 200 miles and then let her rip....

Sometimes you just have to show her whos boss....

Probably just as important if not more. Check how tight the pistons are on a brand new production built LS motor. Basically an interference fit - pretty much zero clearance, until the coating wears in a bit. Valves to guides are pretty tight also when green fresh. No reason to take those tight components to max loads on day one. You also have the rear diff gears that need a break in period... no gear specialist will ever tell you to beat on a brand new gear set.

The fact the cars survive hard break ins is more a testament to the quality of modern production. Not that it was any great thing you just did to your car.

All they can do is make recommendations, what you actually do with your car is up to you. Beat the hell out it if you wish.

[IcePick06]

Originally Posted by Erik@Torq

Ferrari takes every single car they buid to there own road course for 5 laps, change the oil and deliver the car.

/Erik

I heard about this too but thought it was a rumor...that's AWESOME These threads always come up I've always broken in my stuff the same: Just drive it like you "NORMALLY" would and you're good to go (i.e. if it's a performance car, drive it like a performance car!) I broke in the bike you see in my avatar on the DYNO before leaving the dealership and then did a trackday 2 weekends later after riding hard in the canyons for a few days; so far it has given me no problems. I broke in my 2005 Vette by driving it like "NORMAL" and it didn't give me any problems--I did have to add oil to it during the 1st few thousand miles but I guess that's normal for some high performance engines

[The Stig]

Originally Posted by Erik@Torq

I broke in my SS by taking her to the road course 2 days after I picked her up and then did an oil change lol. 45k of extremely hard road racing and 3 x 6000 mile road trips miles later she is still 100%!

hard break in FTW

[radz28]

Change the diff' fluid probably as a precaution from production and assembly contaminates circulating in and around clutches and bearings and such. It sounds like they just want you to start with new, fresh fluid free of all possible degris and other crap for racing where these can be a bigger problem.

[Kluch]

Originally Posted by Sven59

Be careful, the car records what you do!

Don't get all "big brother" about it. No one is voiding a warranty over a rough break-in.

[Lonny Doyle]

Before dismissing GM's break in period I would suggest doing some research as to why it was recommended.

I do feel like it would be beneficial for GM to give customers a reason for break in besides "because we say so".

I have been in the racing industry for many years as a machinist, engine builder, head porter, R&D and Driver and I will do a 1500 mile break in period.

There are a lot of new components in a car sliding together that need to have a break in period. A good example are rear end gears.

When you set up a new set of rear end gears there is a break in period that should be followed. A new set of gears will always run hotter than a set after break in. This is because when the teeth of the gears are ground there are microscopic peaks and valleys. Until these peaks are worn down to form a plateau for the oil, the gear teeth can make contact with each other instead maintaining an oil film between them. This is what causes the heat.

This is also true with piston and cylinders. Cylinders are honed leaving a cross hatch than needs to be worn down to form a plateau for the oil. This why a new engine may use a little oil at first. The rings are riding on top of the peaks.

If you break the engine slowly these peaks come off as very small particles that are too small to cause any small scratches that are in line with piston travel. If you take your brand new engine and put a lot of load on it, it can cause several problems, one is that you can put enough side load on the piston to cause these peaks to make contact with the dry film lubricant that is applied to the piston skirts and wear it away prematurely.

Another is the peaks left on the cylinders from honing can break of in slightly larger particles that cause scaring of the cylinders in the same direction of travel which makes the cylinders not seal quite as well.

Also with more contact there is more heat which causes the cylinder to distort to a slightly different shape than it will after it is properly broken in. This means your rings first have to seat them selves to a cylinder that was running abnormal temperatures in odd places and then wear to fit the cylinder that has eventually plateaued.

Engine bearings are coated with a material that smooths to match the slight imperfection of the cranks. Even though a crank is ground to very close tolerances they are not perfect. They also need to run long enough to plateau the high spots so when it is under a load it has a nice surface to keep a film of oil between the bearings and the crank. When an engine is machined they machine them very straight, but when you warm them up they do not expand the same all over. This can cause the main bores to not stay perfectly inline with each other. This causes the crank bearings to be a little tight in some places. Allowing the bearing to break in slowly again creates smaller particles that tend to leave the bearings smoother.

You also should never run an engine hard until it has completely warmed up. All of these components are broken in in a warmed up condition and that is when they are the strongest.

I know that it is unlikely that anyone will have a problem if they decide not to break in there cars as recommended by GM but it is only about 30 hours of driving. Take a road trip up through the mountains and it will be done before you know it.

Is it worth the risk?

[kbar4782]

Originally Posted by Lonny Doyle

Before dismissing GM's break in period I would suggest doing some research as to why it was recommended.

I do feel like it would be beneficial for GM to give customers a reason for break in besides "because we say so".

I have been in the racing industry for many years as a machinist, engine builder, head porter, R&D and Driver and I will do a 1500 mile break in period.

There are a lot of new components in a car sliding together that need to have a break in period. A good example are rear end gears.

When you set up a new set of rear end gears there is a break in period that should be followed. A new set of gears will always run hotter than a set after break in. This is because when the teeth of the gears are ground there are microscopic peaks and valleys. Until these peaks are worn down to form a plateau for the oil, the gear teeth can make contact with each other instead maintaining an oil film between them. This is what causes the heat.

This is also true with piston and cylinders. Cylinders are honed leaving a cross hatch than needs to be worn down to form a plateau for the oil. This why a new engine may use a little oil at first. The rings are riding on top of the peaks.

If you break the engine slowly these peaks come off as very small particles that are too small to cause any small scratches that are in line with piston travel. If you take your brand new engine and put a lot of load on it, it can cause several problems, one is that you can put enough side load on the piston to cause these peaks to make contact with the dry film lubricant that is applied to the piston skirts and wear it away prematurely.

Another is the peaks left on the cylinders from honing can break of in slightly larger particles that cause scaring of the cylinders in the same direction of travel which makes the cylinders not seal quite as well.

Also with more contact there is more heat which causes the cylinder to distort to a slightly different shape than it will after it is properly broken in. This means your rings first have to seat them selves to a cylinder that was running abnormal temperatures in odd places and then wear to fit the cylinder that has eventually plateaued.

Engine bearings are coated with a material that smooths to match the slight imperfection of the cranks. Even though a crank is ground to very close tolerances they are not perfect. They also need to run long enough to plateau the high spots so when it is under a load it has a nice surface to keep a film of oil between the bearings and the crank. When an engine is machined they machine them very straight, but when you warm them up they do not expand the same all over. This can cause the main bores to not stay perfectly inline with each other. This causes the crank bearings to be a little tight in some places. Allowing the bearing to break in slowly again creates smaller particles that tend to leave the bearings smoother.

You also should never run an engine hard until it has completely warmed up. All of these components are broken in in a warmed up condition and that is when they are the strongest.

I know that it is unlikely that anyone will have a problem if they decide not to break in there cars as recommended by GM but it is only about 30 hours of driving. Take a road trip up through the mountains and it will be done before you know it.

Is it worth the risk?

I'm not an engine builder, but this also makes sense. This is the route I'm gonna go.

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