Hello to everyone, My car Nissan Qashqai 2010 with MR20DE engine is coming to an end in it's warranty period and I am starting to think about changing the oil myself and not using the official dealership services. It looks like official Nissan dealers in Switzerland are mostly using ELF oils since Nissan is a partner of Renault. The exact oil used in my car is ELF Evolution 900 NF 5W40. I am not a huge fun of french oils and I would like to switch to Castrol or GC (as it is called in this forum) since I am living near Germany and I can order GC for the same price as ELF or cheaper (at dealership they charge for ELF much more it would cost to buy GC directly from Germany). I am inspired to buy from Germany mostly by reading this post: http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2721206/1 So I took a look at different oils I can buy and I can see that most of the 5W40 offered by Castrol are actually not "VOLLSYNTHESE" (fully syntetic) but "HC SYNTHESE" (hydrocracking syntentic). I can see that most of the VOLLSYNTHESE oils are 0W40, for example: 1) Castrol EDGE FST 0W-40 A3/B4 http://www.autoteile-meile.ch/%C3%96le/Castrol/EDGE-FST-0W-40-A3-B4/p-OIL-182 2) Castrol EDGE Titanium FST 0W-40 A3/B4 http://www.autoteile-meile.ch/%C3%96le/Castrol/EDGE-Titanium-FST-0W-40-A3-B4/p-OIL-475 My question is: will there be any significant disadvantage for me to switch to 0W40 from 5W40? I went through many pages of this forum I can see that people discussing this topic here are forming mainly two opposite opinions: 1) 0W40 is better than 5W40 since it offers more protection in cold start and is more chemically stable 2) 0W40 is worse than 5W40 since it has more drain and during the cold start the parts of engine are not covered with enough oil It is important to note that in the area where I live the winters are warm and it is rare to have lower temperature than -10 C (14 F) during the winter. The usual temperature at winter is from 2 to 5 degrees C (35 to 41 degrees F). So, will using 0W in such warm conditions do any harm to engine? Thanks for any advise or opinion on this matter!