Originally Posted by BadJack
If you look in the owners manual for a new Harley Davidson motorcycle they only recommend using the Harley Davidson brand, HD360 or Syn3, motor oil, but the manual says in an emergency the rider should use an oil formulated for diesel engine's, and they list API standards CH-4, CI-4 and CJ-4.
Does anyone know why Harley Davidson is recommending a replacement motor oil formulated for diesel engines? Does that mean all other brand motor oil's formulated for motorcycles like Mobil 1 or Valvoline are bad for Harley Davidson engine's?
Here is my opinion;
I assume based on VOA's and UOA's that HD oil is formulated like a diesel oil. I assume maybe Harley is more concerned about piston/ring deposits which can/will cause wear/keeping the engine clean and why the diesel recommendation. This is pretty much for all the twin cam engines that I know of and certainly for all HD touring bikes.
With that said, most people use either HD oil or any number of motorcycle oils and automotive oils with no ill effects that we know of. The twin cam engine is a great engine and I doubt you will have an issue with any good modern oil.
I personally stick to the "script" meaning, even though I dont use HD oil, I do use the oil they say can be used in an "emergency" and that is a diesel oil rated API CI4+. On the back of the container it also says it meets the API SL. Whats more, the oil is not expensive and reasonably priced at roughly $25 for a 2 gallon container sold on line by Rural King, also others but that is who I use to get it shipped to my home.
Like other oils, the oil I use has turned in terrific UOAs and I continue to use it exclusively. That oil is Mystic JT8 15w50 a Citgo product. Below is their spec sheet. I also believe they make HD oil and Citgo markets many oils including not only automobiles but Marine oils and lubricants. I look at them as a respected company.
http://docs.mystiklubes.com/msds_pi/M20096.pdf
If your interested in my UOA's here is my last UOA posted in BITOG from late last year. There are 5 UOAs on here all Mystic JT8 15w50. Keep in mind the UOAs on my sheet dated around 2015 was when the engine was still new and besides flushing out break-in metals also was flushing out the remainder of the HD oil so the first 2 UOAs will still have some of the HD oil skewing the make up of the oil.
The first oil change I did was HD and I am unsure if the second was or not. I changed frequently in the beginning and still change before the 5000 recommended OCI.
Mystik JT8 - UOAs - Click
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