Would like your advise on whether it's needed and recommended, or gimmick to run a high mileage oil on a vehicle with no leaks and no burning oil issues, but with 141K on the clock?

Been using 10w-30 dino Havoline, but when I went to grab a case, a guy at Advanced Auto said he highly recommended to run Havoline's 5w-30 high mileage oil instead.

My understanding is it's somewhat thicker then a straight 5w-30?

Or should I run the 10w-30 high mileage oil?

I am going to switch to 5w-30 for the winter, but is there harm in running this all summer long in temps 90-100 degrees with lots of mountain driving?

FWIW, I do have slight weeping occuring around the oil pan gasket but no leaking, truck only uses 1/4-1/2 qt in 3K miles.

I am going to switch to 5w-30 for the winter, but is there harm in running this all summer long in temps 90-100 degrees with lots of mountain driving?

5W30 and 10W30 should have the same viscosity when hot.

True - I forgot about that part.

Ok, then let me ask this - how bout Rotella 5w-40?