Hi peeps, i think i used a correct title, if not, let me know i'll use a specific oil designation for ease what would be the negative effects, if any, for using a 5w40 during warm/hot weather instead of 10w40 or 15w40 etc notice the focus is on the first number (cold temp designation/rating)Hey guys, don't hate on me too much for starting another oil thread Went to the local parts store to pick up some Rotella T6 as that was recommended in another thread that I was browsing, but they only had it in 5w40 The vehicle mainly lives in the desert area between Riverside, CA and Las Vegas I don't know enough to know if that will suffice for the conditions that I drive inHowdy y'all, i have spent the entire day reseaching this topic The 2 brands in question are Mobile Delvac 1 5w40 vs Amsoils 10w40 There has not been any lengthy (or for that matter, recent) posts about amsoils 10w40 product I ran the 10w for several oil changes and was happy i don't mind the extra cush Mb ...