I am not ignoring their instructions on break-in. Why would you suggest I am?
I'm going to assume you've read the manual. They are very specific as to what they want you to do and not to do. For the first 500 miles they expect you to keep it to <4000 rpm and vary the rpm. In addition they want you to burnish the brakes and break in the tires. For the brakes they give a specific procedure to do so. If it were critical to follow an arcane engine break in procedure they would tell you. Frankly I'm impressed that they've enforced a break in period electronically. Good show on their part. For myself I'll follow the break in procedure then begin flogging it senseless.
There is no mention of break in oils (dino or dexos) differing viscosities, etc.
From the 2014 Manual
New Vehicle Break-In
Follow these recommended guidelines during the first 2414 km (1500 mi) of driving this vehicle.
Parts have a break-in period and performance will be better in the long run.
For the first 322 km (200 mi):
To break in new tires, drive at moderate speeds and avoid hard cornering for the first 322 km (200 mi).
New brake linings also need a break- in period. Avoid making hard stops during the first
322 km (200 mi). This is recommended every time brake linings are replaced.
For the first 800 km (500 mi):
Avoid full throttle starts and abrupt stops.
Do not exceed 4000 rpm.
Avoid driving at any one constant speed, fast or slow, including the use of cruise control.
Avoid downshifting to brake or slow the vehicle when the engine speed will exceed 4000 rpm.
Do not let the engine labor. Never lug the engine. With a manual transmission, shift to the next lower gear. This rule applies at all times, not just during the break-in period.
For the first 2414 km (1500 mi):
Do not participate in track events, sport driving schools, or similar activities during the first 2414 km (1500 mi).
Check engine oil with every refueling and add if necessary. Oil and fuel consumption may be higher than normal during the first 2414 km (1500 mi)
By comparison if you look in section 9-5 under Track Events and Competitive you will see a list of recommendations for changes in viscosity, alignment, pressure, etc. GM appears to be open about what they do and do not want you to do.