Hey Everybody Got a question for all the experts on here. My current work vehicle is a 2007 Hyundai veracruz as described in the post title. Owners manual calls for 5w20, however 5w30 is also allowed and also 10w30 in warmer temperatures. It has the lamda 3.8 v6 engine with 177k on the odometer. I've personally put around 50k in it as I drive a lot of highway miles due to my job. It seems to like thicker oil, just basing this on engine quietness and nothing scientific. Current full is 5.5 quarts of Castrol gtx ultraclean 5w30 with a Fram TG9999 filter. I pretty much stick with the oci of around 7500 miles per the Owners manual. It's pretty quiet with this oil. I've also got 25 quarts of Supertech synthetic 5w30 stashed because I got it cheap but I also have been using 5w30 in my wife's escape so it definitely won't be wasted. My question is would there be any advantage in switching to a 0w40 for the hot summer months at least? Keep in mind my foot always seems very heavy and I frequently run 80 to 85 down long stretches of interstate. Any opinions are welcome.