Water will evaporate from oil at most any temperature, just faster as temp increases. My old Evo RK oil temps almost never exceeded 180° and two lab tests, one in summer and one in winter, showed an acceptable TBN (Total Base Number) after 5k. That means the oil was still capable of neutralizing acids at that point in time.

I spoke with a Mobil 1 oil engineer involved in their racing program a couple of years ago and he said that crankcase dilution (water and acid in oil) is not as much of a problem today as in the past. This is because oil formulations are better and gas contains less sulfur (water + sulfur = H2SO4).

 

"Normal" and "optimal" aren't the same thing. I wouldn't be comfortable running any engine at 230° at all times, as for one thing it will accelerate the oxidization of oil, even if synthetic. I think I may be more sensitive than most about this, but the more I read about oil the more I believe keeping oil as close to 180° is best, although this won't happen with any TC engine that runs in 70° or higher weather, IMO.

 

This is a little off-topic from the original post but what the heck.

I very rarely check my oil at operating temperature.

I know what the manual says, but just because the manual says to check the oil hot doesn't mean it's the only way, or even that it's the best way. That can be a matter of opinion.

I have done a correlation between operating temp oil level and room temperature oil level on my bike and now I check my oil at room temperature. No more uncomfortably hot or burnt hands for me. In my opinion, this is the better way.

On my bike, the cold vs. hot oil level is approximately 1/4" on the dipstick.

 

Oil temps on my stock 2010 Street Glide (no oil cooler) with a stage 1 air cleaner, a Vance and Hines Pro Pipe Amsoil engine oil and a PCV runs almost exclusively in the 220 range fully hot. It has never gone above 230 since I purchased the Temp dip stick and have been monitoring it. It hit 230 twice in stopped creeping traffic and around 85 F. I can live with that!

 

I never said anything about "optimal" or "ideal", I was just trying to answer the OP's question as simply as possible.

 

I know, and what you reported as HD's spec was correct. I just wanted to clarify that HD's idea of "normal" might not be where I or others would want to run our bikes. OTOH some others might disagree and feel this is a good oil temperature to run, which is okay since it probably wouldn't make too much difference if oil changes were made at reasonable intervals and oil temps didn't exceed 230° often.

 

With an oil cooler and Cobra Fi2000R programmer my TC96's run 200 all day long with air temps to 85 degrees.

 

I will probably add a stock Harley oil cooler to mine as added protection this winter.

 

How effective is an oil cooler going to be when stopped in traffic? Who needs one when the bike is moving? Why even care what the operating temp is? There isn't much you are going to be able to do about it.

 

Anything that can be done to reduce oil temps is a good thing. If an oil cooler will bring mine down from an operating temp of 220 to a temp of 200, I would consider that to be beneficial to the longevity of the motor and will keep the oils protection package in better shape longer.. Thankfully I don't get caught in traffic much in Vermont.