Hello Everyone, first post here so bear with me. After 33 years of driving and using dino oil, I would like to switch to Mobil 1 in my new 2004 Altima. The owner's manual recommends 5w-30 with 10w-30 and 10w-40 acceptable when temps are over 0 degrees F but says Nissan does not recommend the use of synthetic oils. I asked the service advisor about that but he was clueless. No knock against dino oils but you guys know how it is. 3 previous cars: 80 Datsun 510-107,000 miles, 87 Sentra-283,000 miles, 96 Sentra-220,000 miles and never a problem. Nissans are cheap to keep and I do my own maintenence. Thanks.