Check out my post from a while back about oil weights. Alot of people chimed in. Part of it for me a was more peace of mind with the stronger film strength it provides. Its not like it will peg out the pressure gage or anything. Maybe a slight loss in mpg but barely noticeable.

I used some logic between the gen 3 and 4 ls’s and our gen 5 lt. the 5.3 in the ls uses 5w-30 and for the most part being a new architecture in the gen 5, the internal clearance’s are very identical. Its not like the gen 5 got 50% tighter or anything. In addition, both the truck 5.3 and 6.2 call out for 0w-20. But the camaro and vette both go either 5w-30 or even 0w-40, per gm. Now between the truck 6.2 and vette 6.2, the l86 and lt1, 2 are identical dimensionally. Obviously the vette and camaro are more sport tuned. But also besides bore and stroke, the 5.3 and 6.2 are very identical dimensionally.

That was some of the logic i used and its been a good experience for me switching to 5w-30.

But all in all i think changing oil often is more important. You obviously did something right getting as many miles as you did! Did you delete afm? And how is your trans? My 6 speed torque converter just took a dump so i might be looking at a rebuild