So I have a GMC Yukon 2016 5.3 V8. The recommended oil is 0w20 which has been used in my car up till now 70,000 km. I live in the Middle-east where the temperature in summer goes up to 50C AND even in winter it stays in the 30s. I was reading about oil grades and it says 0W20 is good for cold climates as the oil is pretty thin and provides immediate lubrication when you start the car. My question is since we don't have much of winter here and the heat is insane why should I use 0w20 I mean 5w40 or 10w40 seems reasonable for the climate even if the company claims that the passageway for the oil is pretty narrow still I would say 0w40 is somewhat understandable but 0w20 is just too thin plus my YUKON is having valve noise which is starting to increase and my friend having the same Yukon with much more kilometers on the clock is putting 5w40 he's Yukon is super quiet no valve sound during idling and plus he says he's car is way more smooth as compared to before when he was putting the factory recommended oil in it. since my Yukon is getting old and the engine has more kilometers on the clock wouldn't it be better if I put 5w40 in it? Because I don't want for few mpg to ruin my Engine because in some videos I heard them saying they have recommended thin oil for better emission and mpg.