Yep...Right there in the service manual....All three grades are approved up to 100 degrees.

And nowhere does it say one is preferred in temps up to 100 degrees.

It does, however, limit the choice depending on the lowest temperature the engine will be used in...

 

Manual says 60 wt above 80 degrees. I run 50 wt dino oil year round.

 

Not getting into a pissing match over it.
Good day.

 

with my 20w 50 im running cold start ups i see great psi.. 40 maybe
its only on the really crazy hot days i see like 3psi at idle in like 95 degree weather . once im going it goes right back to between 25 or 30
today the heat index was 100... short trip home from work all was good hitting 10,15 psi at idle with oil temp at 190ish ..
longer ride yesterday.. highway i was great..25, 30 psi oil temp s at 210ish
got off the highway.. stuck at a light for a few min idle was around 4 psi oil temp went to 225 ish maybe 230
and it was another 95 degree day ... and she was a bit noisy
just seems to be the crazy heat.. other then that shes great
ill still give it a go with a qt of 60w and the rest 20w50 and see i mean it cant hurt

 

We're conditioned by our experience with car engines to think of oil pressure as a measure of the engine's health. And for car engines, with their shell bearings, that's kind of true.

HD motors, with their roller bearings, are entirely different. They don't need pressure in the same way cars do. They really don't need pressure at all.

If you ever see something like 30PSI on an HD engine that's up to full operating temperature, that is an indication of trouble.

Adding ever thicker oil just so you can goose up the number on your gauge is a bad idea. One of the key functions of oil in an air cooled motor is to pull heat out of the engine. Thicker oil flows more slowly. That's the opposite of what you want.

Run in-spec oil. Put a piece of tape over your gauge.

 

i like the tape over the gauge idea .. kinda wish i never put the gauge in now lol
was gunna run syn oil but, shes a pretty old bike at this point, and im just running what the PO ran since he bought the bike new in 98

 

well i drained the tank and did a oil change even though this oil only had like 200 miles on it
i did 1 qt of 60w and the rest 20w50 all dino oil

warmed her up a bit before a ride .. did a healthy ride maybe a hr, maybe half was kinda stop and go
i did notice the top end wasnt as noisy , at idle, half way through the ride i was at 10 psi and the temp was at 200 ish
was 86 here today humidity wasnt as bad as monday, tues but i was giving her the guns a good bit. and it made a slight difference

figure wth ill try it .... ill run this till end of august then run straight 50 most likely.. my bike never sees weather below 50 so
and shes in a heated garage
worth a shot trying it least in summer months...

 

We use a lot of Spectro 25W60 in routine services.
Folks notice it.
Scott

 

We have cold winters in E. Tx. Never have a problem with straight 50w on starts. Ride down to 30 temps. 55k on 98, small seep on rear jug base. So what. Ken

 

Chiming in just for another data point. ( I'm also not into pissing contests, and know that many other choices work well. Just saying what has worked for me)
I switched to Synthetic oil when my 1995 bike was brand new just after the first, and only, dealer oil change.

For 26 years I have been running:

Mobil 1 V-Twin Fully Synthetic 20-50 which is recommend by Mobil in the engine

For the transmission, I have tried synthetic gear oil, Mobil 1 V-Twin, and Mobil 1 Racing oil. Now using the Synthetic Mobil 1 4t 10W-40 racing oil, which is recommend by Mobil.
For the primary, I use the Mobil 1 4T 10W-40 racing oil, which is recommend by Mobil. (although I have also used the V-Twin 20-50 in the past)

I'm not so picky about the oil filter. I have used Harley, WIx, Napa, K&N, and even Toyota filters (same size as what I used on my old 4runner) All met the the same specs. Chrome K &N on it last oil change because it is pretty.

A convenient way to purchase the oil and filters is through WALMART. Went online and ordered. Delivered to door. Better prices and free shipping. Can't beat it.