Been following this thread and find it interesting. Just some random thoughts...

Steve and others make good points that oil temperature is often running hot at low speed w/o a fan added. On the other hand Harley engineers apparently don't see this as a problem at least at this point. If premature oil degradation, leading to lubrication caused failure, turns out to be an issue I imagine we will see thermostat triggered fans or even water cooling become standard on all M8 motors to "correct their mistake". One negative with mounting a motor/fan at a radiator is that other than when operating at low speed with fan running its presence actually obstructs airflow.

While HD certainly could have designed an inadequate oil cooling system in this motor I'm not yet convinced they have.

Suzuki, BMW, and others have been successfully manufacturing motorcycles utilizing oil cooled heads, the exhaust valve area in particular, for years w/o any problems that I'm aware of. This certainly "stresses" oil but modern oil with a flash point well over 430 degrees (synthetic is even higher) is vastly improved relative to what was out there even 10 years ago. We can probably thank the proliferation of turbo chargers in autos and trucks for these developments.

If I had a new M8 Road King (I don't but wish I did) I'd use a good quality, full synthetic, oil and change it by 5,000 miles and forgo adding a fan to the radiator.

 

I don't see how the fan obstructs airflow to the oil cooler anymore than all the other stuff behind it. You do know the fan is mounted on the back of the cooler right? And it's a very minimalist designed fan to boot.

 

I believe he means the fan shroud. Like in cars, if the fan isn't actively pulling air while moving at low speed, the shroud creates a high pressure barrier to naturally flowing air, Yes, even from behind the radiator. Only becomes a problem if the fan itself fails. In theory anyway. I have no data on this particular application to know for sure. Probably fine.

 

The only time oil temps have been an issue is on the internet.

 

some real truth here..ton of Harley owners out there noticed oil temp issues subside once they did away with the oil temp dipsticks..half of the bikes we've owned didn't even come with oil coolers and we didn't install them..that being said, newly designed oil cooled M8 I opted for it because wife's Freewheeler came with one and we tour a lot together in the Summer and inevitably find ourselves in situations like unexpected road construction delays, traffic problems, etc. So might as well have us both dealing with the same situations without concerns.

 

To be honest no I haven't looked closely behind an M8's oil cooler. I assume it is like water cooled radiators, a small motor and fan on the back side. Any object in front of or right behind a radiator has to have some effect but its presence probably just minimally disturbs airflow when moving. The benefit is at walking speed or stopped.

 

Not sure what to think with the conflicting stories as to when the fan should be on. Mine has never been on yet. Was at the dealer today and its enabled, the techs say it wont come on till the oil reaches temp. He did not know what that temp was but he says its not coming on in this cold weather unless I was to idle the engine a very long time.

 

yeah, this is bizarre..so far I see that 3 of us have been able to validate it's functioning even at 50 degrees and below..3 others haven't been able to validate it's functioning even at temps above 50..strange..so batting .500, which would be incredible if you were a Major League hitter

 

Shitty thing is, they probably won't issue a recall if the fans are crap because it's not a safety issue or one that will cause engine problems. They come without fans on the cooler so even if the thing never turns on there won't be any engine issues.

 

yeah, I'm really curious as to how these issues get resolved..1 year warranty, wife's will be factory 2 year..'if' mine fails outside that I'll throw the OEM on and switch to synthetic instead of shelling out another $400 ish..but getting way ahead of myself here as I don't believe there's a 50% failure rate..LOL..did anyone try 'rebooting' it by unplugging and plugging it back in? worth a shot I suppose...but yeah, if you ride it until operating temperature, park and let it idle while putting you're hand down there, there will be zero doubt if it's on or not