The owners manual for my car recommends 20w-40 or 20w-50 from temps of 32f up to "oh my gawd it's hottt".

It also shows 15w-40 and 15w-50 with same upper temp allowance, but downward to 5f, 10w-40 down to 0 f, and 5w-50 for any temp range found on planet Earth.

I picked 20w-50 because my mechanic recommended it, and we do get those "oh my gawd it's hottt" days down here in Houston.

Understand, the lifters aren't ticking when the motor is running - only at initial startup. I don't think the viscosity of the oil is going to determine how quickly the lifter leaks down. In fact, I would think a thinner oil might leak down more quickly. That assumption is based on my thinking that the problem is related to coking of the oil around the check-ball and sealing surfaces in the lifter, allowing the oil to leak back out when the pressure drops.

I will concede that the single lifter that is sometimes reluctant to pump up, but does so once the motor warms up, is slow to pump up because of the thicker oil.

With the amount of miles I put on the car, and my penchant for doing 3000 mile changes, I've stockpiled 20w-50 oil - grabbing what I can when the local Advance Autoparts puts it on sale. I'm fairly certain I can return it and swap for a lower viscosity oil, but I'm not convinced that's going to do anything for me.