When I had my 500 mile break-in oil change done, my local dealer used Mobil 1 5-30 wt after showing him Globel Connect Message #G_0000205212. Also they mentioned that since the break-in oil change was required by GM that it would not go against my other free oil changes ( 4 oil changes in 2 years ) and that they will use 5-30wt Mobil 1 and only on the Corvettes.
GM Globle Connect: Ref. number Service/Operation / G_0000208346 States:
In the event a customer paid an upcharge for Mobil 1 under the Chevrolet Complete Care Program, customers should be directed to contact Executive CAC at (855) 435-7284 or email
helpcustomer@gm.com for reimburstment. Also if you have any issues with your dealer call (855) 435-7284. Hope this info helps !!