Continue using the Pennzoil Conventional 10w30 that you are using for 3K miles. Change the oil again using the Pennzoil Conventional 10w30 for another 3K. After the second oil change start using either your Red Line 5w30 or 10w30. Go ahead now and get a bottle of the Red Line Break In Additive and put half a bottle in now, then use the other half bottle on the 3K change. Then enjoy your Vette.
Red Line Engine Oil Break-In Additive
Provides conventional motor oils with antiwear additives like zinc and phosphorus (ZDDP) necessary to protect against camshaft and valvetrain damage on break-in
Allow pistons rings to seat properly with less-slick oil, while antiwear additives protect other engines components to avoid excessive wear
Can also be used in conventional and synthetic oils during regular operation, providing an extra package of protection otherwise not found in most motor oils
16oz bottle treats up to 12 quarts of motor oil--in many cases, one bottle can serve two engines or oil changes
Red Line Engine Oil Break-In Additive
Provides conventional motor oils with antiwear additives like zinc and phosphorus (ZDDP) necessary to protect against camshaft and valvetrain damage on break-in
Allow pistons rings to seat properly with less-slick oil, while antiwear additives protect other engines components to avoid excessive wear
Can also be used in conventional and synthetic oils during regular operation, providing an extra package of protection otherwise not found in most motor oils
16oz bottle treats up to 12 quarts of motor oil--in many cases, one bottle can serve two engines or oil changes