On long trip of 5+ hours my 2011 DTS seems to use more coolant?

Hello and welcome to ExpertHelp.com! My name is Ramy De Jesus and I'm going to do everything in my power to answer your question to your full satisfaction!

Before we get started, I want to remind you ExpertHelp.com is an independent professional support company. We are not associated with Cadillac nor are we paid to provide support on their behalf. However, we have helped hundreds of customers with similar questions and believe we can help you too. OK, let’s get started! :)

I’m available to chat now. Please let me know that you are ready by posting a response. I’ll leave my chat session open for the next 15 minutes or so and wait for your reply. If I don’t catch you this time, please respond with a few times (including your timezone) that work best for you and we can connect then.

Hi Tim! Thank you for choosing ExpertHelp.com. May I know when did this issue started? Have you done any steps? Once you are ready to continue please let me know by typing "ready" then click on the Blue Send Response button to post your response. I will be standing by for your response.

Thank you for your response. Have you check for any leak on the radiator hose? 

If there is no leak on the radiator and the radiator hose are in great condition, then there is a problem with your head gasket issue. Have it check or if needs to be replace have it replace to avoid this coolant issue. Please advise me if this answer and help you with your issue. I will be standing by for your response.