Is it true that Ford changed recommended type of oil for modulars from 5W20 to 5W30 only for ecological reasons ? I mean which oil will be better for engine, not for eco-freaks. When I was bought my 09 GM I poured 5W20 Amsoil Signatur Series oil, but I think that engine runs a little bit louder at cold start than before. I don't know what type of oil previous owner used, car don't burn oil. At the begining of january I will change oil and filters and I wonder if I should use 5W30.