Mobil now makes 0w-30 and even 0w-20. They advertise they meet or exceed the 5w-30/20 and 10w-30 oils and are approved by mfgrs. I'm a firm beliver of thin(er) viscosity on cold start and thicker (a little) on hot run. I use 0w-30 M1 on my other two vehicles and have gotten the best UOAs since I've been doing them. Your experience on thicker oil to stop the ticking may be because it leaks down more slowly?? When I used 10w-30 I had bad ticking on start-up.

92 Montero LS 3.0L V6 Auto, Stock, Original owner, 185,800K miles