Pablo and El Chapo thank you for your service!

 

If you have a Oil Cooled M8 I would recommend you run a full Syn oil. If yours is Twin Cooled then either would be fine. The reason for the difference is that the Oil Cooled heads have a small a passageway for the oil to travel through, down through the exhaust port area. When the bike is turned off the oil from this area drains back into the oil pan, leaving behind a thin film of oil. All the heat from the exhaust port may cause that oil over time to dry or coke as its called and could plug the small passageway. Use a full Syn oil and that will not happen. Since this passageway is not in the Twin Cooled heads it's not an issue. So it has the same issue as a turbo does, due to the exhaust heat involved.

 

 

 

I would not worry about "coking" in this application. There are many high temp locations in our engines that have tiny oil passages running through them. Some that the oil drains from as well. Never any problems.

 

I would say quite well MJ. The oil is heated by the heads, in order to primarily keep the exhaust valves cool if memory serves. I don't think the intent of the design was to match the effectiveness of a coolant (water-based) system but just to keep the heat down to a manageable level. So every degree it carries out but not back in is enough to make the difference between bad things happening in an over-heated scenario, and not. And if the passageways are pressurized we might be surprised at how much heat (and oil), is transferred between the heads and the cooler coils. I do know that I'm impressed with what Harley has done with the M8, at least so far as how my motor works in my bike. I couldn't be happier with the way it runs, and how hard it pulls.

 

Where do you think these tiny oil passages you describe might be in the M8 engine? The Only ones that I know of, run down the divider to the exhaust seat area then out of the head to the pan that see close to 900+ deg exhaust heat! The rest of the engine only see's near a high of 350 deg by oil passageways that are double in diameter to what's in the head.

 

twas a joke i could resist. Ha

 

appreciate the comments, opinions and suggestions/recommendations, etc. folks..I do believe we'll stay the course with conventional oil since we have fan assisted oil coolers, ESPs...part of me wants to keep these stock (consider our SE Stage 1s for all intents and purposes stock) continue to ride the heck out of em' and rack up the miles..like the idea of a challenge to see how long they hold up by the book, kinda' 'take one for the team' and give them a long term stress test to see what they are capable of from the factory...they run so freaking good for how we use them, pure enjoyment and the Laguna Orange is an advantage to keep us from upgrading..that and they're paid for...we'll see, been known to be a hypocrite and have to eat my words!

 

Using M1 automotive motor oil and never gonna pay again for "motorcycle oil" on my 2012 Fatboy.