Oil Temps
Stellar HDF Member
Joined: Mar 2011
Posts: 3,482
Likes: 631
From: NorCal Rocklin
The reason you want to know is because oil breaks down due to HEAT. So you can take brand new oil and ruin it by running it to hot in as little as 50 miles. So now it does not lubricate the engine components and you then ruin the engine. So is that OK with you? Regular oil like HD puts into the bikes is not any good above 280 deg F for very long, synthetic oil on the other had will go to 330 F without issue. Most regular oil manufactures will tell you to run oil between 180 - 250 F for normal operation range so 290 is a bad deal and is breaking the oil down.
HD EFI Guru
Joined: Jan 2008
Posts: 4,477
Likes: 4,752
The whole point Im trying to make is that OIL always breaks down. So running it cooler with slow the breakdown process, if that is what you are saying. The broken down oil is still in the engine circulating. Still lubricating the engine, unless it gets somehow consumed. I think you guys are making yourself miserable on purpose by sweating the small stuff like this. Just ride it and make sure there's oil in it. It's not the end of the world.
Look the engine is sound it just has some growing pains. I find it funny that HD figured it was necessary to put a fan cooled, oil cooler on all the Trikes and Police model bikes that come with the Oil cooled version of the M8 engine. There must be a reason and I think that what testing we have done shows why! Now once that cooler gets here we will test it and if the weather stays the same we will get the results and post them.
Last edited by Steve Cole; Oct 21, 2016 at 02:36 PM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,893
Likes: 8,001
From: poway
I think you need to take a look at what you've stated. Once the oil breaks down it no longer lubricates and there in lies the problem. So you might as well being running water in the sump instead of oil. If you believe that's OK, then you do not need to worry about it.
Look the engine is sound it just has some growing pains. I find it funny that HD figured it was necessary to put a fan cooled, oil cooler on all the Trikes and Police model bikes that come with the Oil cooled version of the M8 engine. There must be a reason and I think that what testing we have done shows why! Now once that cooler gets here we will test it and if the weather stays the same we will get the results and post them.
Look the engine is sound it just has some growing pains. I find it funny that HD figured it was necessary to put a fan cooled, oil cooler on all the Trikes and Police model bikes that come with the Oil cooled version of the M8 engine. There must be a reason and I think that what testing we have done shows why! Now once that cooler gets here we will test it and if the weather stays the same we will get the results and post them.
Anyway, if the oil sees too much temp, the longer molecules that create viscosity simply break down to a lower viscosity and not water.. As you state, use synthetic (molecules are more stable and tolerate heat better). I'd also suggest changing oil more frequent oil changes.
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Road Master
Joined: Aug 2005
Posts: 761
Likes: 124
From: College Station TX
Steve, I went into town today and was in red light traffic. I have not seen those temps you are. Next thing is I'll check the thermometer to see if it is reading right.
HD EFI Guru
Joined: Jan 2008
Posts: 4,477
Likes: 4,752
I'm no oil expert.. Pretty much hate the discussions, especially when some one says " I use Redpurplemolyway 5w/70 synthetic oil and it's the best I I've ever run!! Wouldn't use anything else!.. Billybong testing lab says I can run this stuff 47 years without issue"
Anyway, if the oil sees too much temp, the longer molecules that create viscosity simply break down to a lower viscosity and not water.. As you state, use synthetic (molecules are more stable and tolerate heat better). I'd also suggest changing oil more frequent oil changes.
Anyway, if the oil sees too much temp, the longer molecules that create viscosity simply break down to a lower viscosity and not water.. As you state, use synthetic (molecules are more stable and tolerate heat better). I'd also suggest changing oil more frequent oil changes.
I just want a simple solution to stop it from happening and if that means adding a fan assisted cooler and synthetic oil then that's what it will get. Let's face it we spend 20 - 30 K on a bike and when we have the time to go ride and enjoy it, I do not want it to break down on me.
Road Master
Joined: Apr 2011
Posts: 1,145
Likes: 98
From: Colorado Springs
I hate the oil stuff as well as it's very hard to get a straight answer. What I do know is that the temperatures being measured are too high and the standard oil is not going to live very long. Yes, I've changed it and will continue to until the cooler comes in and I can test that. My hope is that it solves the high temperatures with the fan assist. The other side of all this has not be discussed yet. The oil gets this hot as the surface temperature it runs across is hotter. So when you shut the engine off and the oil runs out of the head and back into the sump you now have a very hot surface with just a thin film of oil on the surface. That can bake into what is commonly called coking. That will occur over and over again and we may see the passageways reduce in size and plug over a long period of time. This occurs in turbocharges and is why they added water cooling to them to slow or stop the process from happening.
I just want a simple solution to stop it from happening and if that means adding a fan assisted cooler and synthetic oil then that's what it will get. Let's face it we spend 20 - 30 K on a bike and when we have the time to go ride and enjoy it, I do not want it to break down on me.
I just want a simple solution to stop it from happening and if that means adding a fan assisted cooler and synthetic oil then that's what it will get. Let's face it we spend 20 - 30 K on a bike and when we have the time to go ride and enjoy it, I do not want it to break down on me.
Harley has made a lot of claims of superiority concerning the M8 versus the TC. Many of these claims, most actually, IMO are very accurate. Heck, some of HD's claims are actually, again IMO, subdued or toned down from reality. In a few important performance aspects the M8 ANNIHILATES the TC. Smoothness and low RPM torque for instance. Among the MOCO's claims however is that the M8 runs cooler than the TC. In the two months I've owned my '17 Street Glide, my observations, much less scientific than yours, are that for the most part the claim is B.S. My M8 gets pretty hot in slow traffic with high ambient temps. I see no difference between my 107" and my 103" when temperature is the issue. However, I haven't felt that the 107" is getting any hotter than my TC 103" H.O. did.
Like many, I am looking to the fan cooled oil cooler, when available, to help mitigate these issues. It seems like pretty cheap insurance. I'm also looking forward to your detailed test of this unit when you purchase one for yourself. A detailed install guide would also be helpful. Is it simple plug and play to the factory wiring harness, etc?
The substance of your posts are, for the most part, very valuable. But maybe leave out a little of "the sky is falling" tone?
Peace out....
Last edited by ocezam; Oct 22, 2016 at 09:42 PM.
Road Master
Joined: Feb 2014
Posts: 1,240
Likes: 170
From: Wisconsin
I noticed right away that My M8 ran hotter than My 2014 stage1 Limited.I have a street tuner and the engine temperature averages 250F to 266F.If the engine temperature is that hot,so is the oil!
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,471
Likes: 2,998
From: Charleston, SC
I agree the new engine feels hotter. My 14 had the same config but was much cooler for whatever reason. The heat is not around the seat thank goodness, but hangs around by the ankles. Pretty warm.
Last edited by lp; Oct 23, 2016 at 09:19 AM.
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Road Master
Joined: Apr 2011
Posts: 1,145
Likes: 98
From: Colorado Springs
Yeah, I'm sure the water cooled heads help a lot. I'd seriously consider a retrofit if it could be done without too much expense. I guess the fan assisted oil cooler will be my only option.
HD EFI Guru
Joined: Jan 2008
Posts: 4,477
Likes: 4,752
For the record this new engine runs well, but it does run hotter. The issues I and others have pointed out are only in slow speed riding. If you do not have to ride in town then I would not worry about it too much. As for Coking in the oil cooled heads and too high of oil temperatures, it is what it is. You can ignore it or do something about it, that is your choice. That does not mean the sky is falling, it just means there is an issue in these conditions in the oil cooled model. If the fix is as simple as the fan assisted oil cooler and synthetic oil, then no big deal. Maybe that is why all the oil cooled M8 Police bikes and oil cooled trikes get the fan assist cooler stock.