Hey guys, I plan on using Castrol 10w 40 next summer for the added protection. I don't believe in these lighter oils. I'm even thinking about 20w 50. What do you think?

Long ago the 10-40 oils had the characteristic of clogging rings because of something in their chemistry. I heard a car mechanic say the same thing within the last year. He would recommend 10-30.
I do know a local mechanic with a 200K LeSabre in which he uses 20-50. Myself I'd jump to the 20w-50. I've noticed my 130K miles LeSabre using some oil. So I may go to that after April and warmer weather next year.

I've always used 20w 50...Castrol also.

what is your reasoning behind prefering heavier weight oils?

Well we had an unusually hot summer and I feel the 10w 30 is too light.

No kidding????????

Got to remember it takes HP to turn a oil pump. thicker the oil harder to pump.
thus less MPG

most of the time GM has awsome oil press. in ther engs. so thick oil is not needed.

just make shure you use a good quality oil (like moble1 syn or Amsoil etc.) you'll be fine.

Since most of the engine wear happens at start up, the thicker the oil the longer it takes to reach the critical parts in your engine and hence more wear. Most of the car companies are going to very thin oil recommendations like 0-20 and 5-20. I would not go this thin but I believe 10-40 is to thick. There is a great site called Bobistheoilguy -see what some experts have to say. Roger

I've used the recommended 10W30 Castrol GTX.

20-50 is awfully thick. I wouldn't personally use it in this car unless I was sure the bearings were going and needed the thickness.