This old girl has 161,000 miles on it. I live in the northeast and use it as a daily driver and weekend family trip vehicle. I have always used mobile 1 5w-30 for oil changes. I have usually changed the oil every 7000 miles or every six months. All the gaskets were replaced two years ago. It does not burn or leak any oil. I am considering changing to mobile 0W 30 or mobile 0W 40 FS for assistance with cold weather starts and because these oil's have great numbers on their PDS. I am a little concerned about having head gasket issues using a 40 weight oil. I would be more comfortable using the 0W 30 for those reasons. Is this warranted? And what would your advice be regarding using either of these oil? Is it wiser to stay with the same oil ? The stats on the mobile 0W 40 look fantastic and it's difficult to choose another option. Thank you in advance for your advice. It's nice to be part of a forum of oil fanatics those around me think I'm nuts for reading and talking about oil so much.