I'm skipping over everyone's comments as this subject is always a debate.

That being said:

--Does an oil cooler lower the oil temp? My UltraCool fan assisted cooler certainly does by as much as 20 degrees.
--Does a 20 degree less oil temp provide more rider comfort? No
--Does a 20 degree less oil temp provide more engine life? Who really knows for sure but less heat can't hurt.
--Are you concerned about road debris damaging the oil cooler? No, the UltraCool comes with a shield on it.
--If you purchased another Harley that didn't have an oil cooler would you install another Ultracool unit on it? Absolutely

 

Last year someone here did a test on engine oil temperature. They tested their oil temperature with and without an oil cooler then they tested with and without cooling fans. His results showed that fans cool the oil much faster and pull more heat from the engine than an oil cooler. Of course, having both would be the best option if money allows.

 

I have both; an oil cooler and mighty mites love jugs fans.
An oil cooler and jug fans are apples and oranges.

The fans do nothing for oil temp but does cool the jugs down.

However in my application the heat that the love jugs displace creates more crotch heat so I only turn them on when I'm in very heavy stop and go traffic or whenever it's a bit cool out as they do provide some warmth.

 

Every air cooled bike I’ve owned had an oil cooler. To each his own.

 

Thoughts.
I like the extra oil capacity.
Oil leak, could be by passed in an emergency.
Cost, HD can be a hobby.

Necessary?
HD tests engines, but to 150K miles?...probably not
Fully loaded, Two-up riding, excess weight, up hill...maybe yes
Arizona, desert heat, etc, ….probably yes.
Stop & go traffic....probably yes.

Adding a fan to a cooler seems like a good idea if any of those serious heating conditions are present.

Good luck in your decision.

 

I'm not saying they can't leak, but here's what mine looks like. I was changing the oil 3 years ago and layed on the floor to straighten the oil cooler fins. There was a small piece of wood stuck in the cooler. Pulled it out, it's been fine ever since. Has 107k on it now...

 

Which is more important? Oil temp or cylinder temp?

 

I have a '15 fat bob,stage 4 done right...i added the DK oil filter relocation kit and got noticeable cooling affects by adding this.There is no danger of a leak by a rock or debris,also added more oil to the system,which can't hurt!

 

Was going through some older thread and I thought I'd try again to ask which is more important: Oil temp or cylinder temp?

 

My 2010 FLHTK came with an oil cooler. My 2016 FLTRU didn't, but it's water cooled. My 2005 FXSTB/I has a Jagg oil cooler on it, but it's also running at 12:1 compression with a massive cam, and it's the bike that'll always be mine (until I die, then it's in my will to go to my daughter).