Phanni

Going into V4 mode is bad,,,,why?
does it hurt your ego?

ea327

My first 500 miles were done on the way home from my Museum delivery. I followed the manual to the letter. I now have just over 8000 miles and have not used one drop of oil. Behave yourself for the first 500 miles. You'll be glad you did.

JerryU

If you have an automatic nothing but manual mode shifting with paddles, stops it from going into 4 cylinder mode. Another big advantage of an M7, ours only goes in when set at ECO!

Yep recently when to Jacksonville from Charleston and took Rt 17 as far as practicle, then as you said short trip on I95 to get to Savannah. However on I95 just use paddles and don't let it get into 7th and 8th. That will also keep it out of 4 cylinder mode.

The key is keeping the rpm at different speeds not the travel speed. So just use different gears even at the same speed. When I brought my C7 Z51 home 120 miles from the dealer just used 4th (direct drive in my M7) and 5th and switched every ~10 minutes. Also did vary the speed from 65 to 75 mph.

Touring, Sport or Track doing nothing different in rpm. Won't hurt or help!

JerryU

It's the same 4 cylinders not getting any air/fuel i.e. combustion. If you are trying to get the rings to wear in properly good to have some blow-by, IMO.

Walt White Coupe

The key is keeping the rpm at different speeds not "just" the travel speed.

Jerry, If you look at the recommendation break-in, it says "speed" referring to "travel speed". As has been said before the "break-in" is for the entire drive train. Just varying the engine speed does not vary the speed of the rest of drive train and that is the purpose of varying the travel speed also. I'd suggest the varying from 65 to 75 mph is okay but a wider variation would be better.

Widgeon5

Though I am no engineer myself, from my reading I gather that the reason for varying "speed" is almost entirely an engine consideration, not the rest of the drive train. And it is engine rpm that should be varied. The reason is that an operating engine has hotter and colder spots within it. These locations change with rpm (and no doubt load.) You want break-in to take place under all of these temperature conditions. So even traveling the same speed, just select a different gear periodically (we have many to choose from.) Shutting down 4 cylinders (V-4 mode) allows much greater temperature variances, and you don't want break-in wear to occur that way. The transmission and differential are breaking in also, of course, but temperature variations are much less of a consideration (no combustion going on), at least if we're driving the car gently as we are supposed to.

blue max

Both the corvette museum and ron fellows school do not recommend the track mode on the highways as the suspension is so stiff if you hit any king of pot hole it can take out the tire and maybe the rim.
Just sayin

NSC5

Uneven break-in given that 4 cylinders are active less of the time.

V4 mode "effects" upon the torque converter (if you have an A8 transmission). Note the scarcity of shudder and other torque converter concerns in the Z06 section of the forum; the LT4 powered Z06 very rarely meets conditions to go into V4 mode unlike the LT1 equipped cars. I don't like my torque converter clutch continuously engaging and disengaging many times per second and from the operational problems apparently it doesn't like it either. M7 equipped C7s don't go into V4 mode unless the owner wants them to (via eco mode) because it doesn't have a torque converter which can be used (or perhaps misused) to dampen vibration resulting from operating a V8 as a V4.

Walt White Coupe

Not to be a wise *** but I am a mechanical engineer. And you are wrong. Break-in is for the entire drive train and other than the engine we are primarily talking about gears in the transmission and differential. At low speeds the loads on those gears are low and the contact patterns are small. A contact pattern is the area of the gear tooth that is actually in contact with it's mating gear. As speed increases the loads increase and the contract pattern gets larger primarily from gear tooth bending. So varying the speed and therefore the load wears in the mating gears from a small area of contact to a larger area of contact.

Borntorun04/17

The ride home would be around 2 hours on thruway or I could add around 1 1/2 hours using non thruway roads going thru small towns. So first ride home isn't really long, Once home most of break in period will be non thruway driving .My initial thought was if I was in manual on thruway I might be able to control RPM easier so they would be constantly at same speed. Also Gonzo mentioned about different driving modes would either Touring or Sport make any difference. Thanks again for all the good info , Dave

Borntorun04/17

Thanks that will give some reading while I wait for car !

Widgeon5

Your analysis makes sense. But let me throw this in. Regarding tooth bending/contact pattern, at any normal steady-state cruising speed, the amount of engine power and torque being used are very low. It is under acceleration that these would change significantly. It seems to me that changing cruising speed would not matter much, except for the acceleration periods involved.

Walt White Coupe

Yes but the load at 30 mph is significantly less than 75 mph and between those two speeds you will see the vast majority of driving so they are very important. A refinement to the break-in procedure would be to also vary the acceleration rate when changing speeds. At the beginning of the break-in period the acceleration rates should be relatively mild with increasing acceleration rates as you go through the 500 mile period and only doing full power rates after the 500 miles.

JerryU

Think you meant Not having the same engine speed which is the goal for ring cylinder wall seating. The key to the gears is not to have them deal with high power which at 60 to 70 mph is a none issue. Agree when home normal driving is fine with no fast starts.

Rebel Yell

Born, there's a lot of varying info here. And really none is better than the other IMO. Just use some common sense, and you'll be fine. It's not an exact science, and doesn't have to be as long as you basically follow the owners manual. I let mine do as it pleased, varied speeds, with nothing over the rpm limit advised in the manual. At 6100 miles mine hasn't used any oil, and everything operates as intended. The main thing is enjoy your ride home, and don't stress the break-in period that much.

VettinFan

Very well said.