WHAT STOPPED THE LIFTER NOISE 2011 DODGE GRAND CARAVAN

Hmmm. Hydraulic lifters are pumped up by the oil and a too low viscosity will cause the lifter to bleed too quickly---equals noise. Now, viscosity will lower metal-to metal contact was it builds a thin surface between mating parts. But like a hammer hitting a nail, that type of contact isnot where the oil's viscosity is effective. Sort of like looking at gears. Hypoid and then worm and worm wheels have greater sliding contact forces than involute gear profiles so heavy duty oils are specified (by that I mean HD oils with great shear strength).
In this regard, I have a story. We had a problem with a foreign-designed piece of machinery that was pistol-hot when operating because it had a hypoid gear set (we're talking maybe 1,500 hp). We tried increasing oil flow and adding some circulating holes. No significant change. Finally, I asked a Mobil rep to take a look. He studied the design and returned with a recommendation. Change to their HD series and we would see a 25% reduction in heat. We tried it and BOOM, the gearbox cooled significantly. The oil was designed for the higher shear forces created. Also note that oil does not take away heat but doesn't allow it to be created. Which is what synthetics do in comparison to dinosaur oils (in synthetics, per him, all the molecules are one size).