I like the Redline 20-60 my temps have dropped from 290* down to 250* I live in So Cal so YMMV with temps. I run my oil 6k miles and have good UOA all the time. with redline or M1 20-50 but I'm sticking with 20-60 it just runs cooler.
I have PUSHED this GREAT Redline oil for years. I only do that for the benefit of the members here. Not a dime made from Redline, JUST the satisfaction I can Help a few members WHO LISTEN out when picking an oil for their ride.
I know many riders that do what you have done, use the 20/50 and when really hot use the 20/60 Redline and their temps Do DROP just like you said yours did.
The oil is a little more costly from 20/50 to 20/60... it is just a few dollars a quart difference but in a hot HOT environment 20/60 truly does the job.
Even here in HOT Az. I have used the 20/50 Redline and it also keep COOL...
Recently, I changed to a 10w60 full synthetic oil and do like it BUT like said in another post IT IS Hard to switch from such a good product like REDLINE.
I may switch back as I am ONLY doing an Experiment with Liqui Moly 10w60...
It got a good report from Blackstone (listed report some place on HDT) but that is because I have a good Clean built 103" motor. AND I Used Redline from the Get-Go... Motor is in excellent shape with about 30,000 miles on it.
BUT that 10w60 fully synthetic Liqui-Moly is another good LOWERING temperature oil for our Harley's.
signed....BUBBIE
YIKES It is post # 14...... Check out the BLAW Blaw there...