WHICH OIL-API Gasoline or Diesel?
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Road Captain
Joined: Oct 2007
Posts: 634
Likes: 8
From: Plum & Nearly
WHICH OIL-API Gasoline or Diesel?
Harley does not publish an API rating for their oils. Many oilsout on the marketcomply with API code SJ and better, I think the latest is SL so that their oils can be sold in various engine markets.
Harley does not advocate using their oils in anything other than their motorcycles so they dont need the API rating...they have tested it in their motors and whatever blend of additives and such they have prescribed is good for their engines.
So if all of these other V-TWIN oil manufacturers say that their oils meet or exceed, lets say, API-SL (which is a gasoline engine oil) and it is good in the Harley engines...........THEN why in the world would Harley-Davidson recommend a DIESEL ENGINE OIL with API codes of CF-4, CG-4, CH-4 and CI-4 to be used in their engines if that was all that was available? 2008 touring manual pages 91 and 92 and it goes back to at least the 2005 touring manual.
I guess what I am saying here is....Why use an alternative engine oil that is API rated for a gasoline engine when H-D recommends oil (granted-to be used in an emergency) that is API rated for Diesel engines.......If API-S? whatever oils are good for the H-D engine as stated by the oil companies...I would think that H-D would have said ........an oil that meets or exceeds API-SL and would not have directly referred to the diesel API certifications.
So would you use oil manufactured for a Diesel or one that is for a gasoline engine?
And dont flame me or show me all the oil studies...I was just making a point.
Harley does not advocate using their oils in anything other than their motorcycles so they dont need the API rating...they have tested it in their motors and whatever blend of additives and such they have prescribed is good for their engines.
So if all of these other V-TWIN oil manufacturers say that their oils meet or exceed, lets say, API-SL (which is a gasoline engine oil) and it is good in the Harley engines...........THEN why in the world would Harley-Davidson recommend a DIESEL ENGINE OIL with API codes of CF-4, CG-4, CH-4 and CI-4 to be used in their engines if that was all that was available? 2008 touring manual pages 91 and 92 and it goes back to at least the 2005 touring manual.
I guess what I am saying here is....Why use an alternative engine oil that is API rated for a gasoline engine when H-D recommends oil (granted-to be used in an emergency) that is API rated for Diesel engines.......If API-S? whatever oils are good for the H-D engine as stated by the oil companies...I would think that H-D would have said ........an oil that meets or exceeds API-SL and would not have directly referred to the diesel API certifications.
So would you use oil manufactured for a Diesel or one that is for a gasoline engine?
And dont flame me or show me all the oil studies...I was just making a point.
Tourer
Joined: Jan 2006
Posts: 308
Likes: 0
From: SUNNY,FL
RE: WHICH OIL-API Gasoline or Diesel?
My guess is that the Motor Co. likes the additives found in most diesel oils.
Diesel oil contains more zinc and other metals that gasoline engine oil is no longer
allowed to contain.
Owners manual specifies diesel, so in emergency I would use diesel oil.
Diesel oil contains more zinc and other metals that gasoline engine oil is no longer
allowed to contain.
Owners manual specifies diesel, so in emergency I would use diesel oil.
Outstanding HDF Member
Joined: Dec 2007
Posts: 2,415
Likes: 197
RE: WHICH OIL-API Gasoline or Diesel?
Red E Glide has it right. I'll just add that Diesel oil not only contains more Zinc and other additives for higher heat and shear resistance, but it doesn't contain real large amounts of friction modifiers found in SOME automotive oil.In my mind, that makes it a better oil to use in our primaries if you don't use an oil specifically made for that purpose.
Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
RE: WHICH OIL-API Gasoline or Diesel?
It's a moot issue. Check the ratings on your favorite oil--you will probably find it meets both the gas and diesel requirements.
(I just looked at my Mobil One 15/50 oil that I use in the Triumphs. It has both ratings clearly stated.)
(I just looked at my Mobil One 15/50 oil that I use in the Triumphs. It has both ratings clearly stated.)
Road Warrior
Joined: Nov 2007
Posts: 1,312
Likes: 1
From: Iowa
RE: WHICH OIL-API Gasoline or Diesel?
I noticed in my manual that if I need to replace oil while on the road and MOCO oil is not available, I should use a diesel oil and haveit changedas soon as possible with the MOCO oil.
Road Captain
Joined: Mar 2007
Posts: 531
Likes: 0
RE: WHICH OIL-API Gasoline or Diesel?
Diesel oil when caught in a pinch,but change out as soon
as possible.Maybe some gas motor oils have the right additives
but if you use the diesel,you don't have to worry about it.
as possible.Maybe some gas motor oils have the right additives
but if you use the diesel,you don't have to worry about it.
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
RE: WHICH OIL-API Gasoline or Diesel?
I'm more cynical about this issue than most of you. My manual says "If it is necessary to add oil and H-D oil is not available, use an oil certified for diesel engines. Acceptable diesel oil designations include: CF-4, CG-4, CH-4, and CI-4." Note the word "include," which most will not heed and makes the entire sentence appear that these designations are the only ones acceptable. The only 20w50 synthetic that I know of that has any of these four designations is Royal Purple, and that may be the reason they have worded the sentence like they have. It appears to place a requirement that will be difficult to meet, thus prompting you to hitchhike to the nearest city to get genuine HD oil rather than put an inferior product in your precious bike.
Further, the manual says "At the first opportunity, see any authorized dealer to change back to 100-percent H-D oil." Boy, sounds urgent, dosen't it? If you don't hurry up and change, your engine will surely degrade before your eyes without genuine H-D oil in the crankcase. This strategy likely sells more overpriced oil, which makes stockholders happy, but is not firmly rooted in reality. The truth is that any 20w50 or 15w50 motor oil will run fine in your H-D in an emergency or otherwise, even mixed with other brands--synthetics of course providing additional advantages over fossil for long-term use. I broke-in my SG in with Castrol GTX, an excellent fossil oil, after 500 miles on the factory install, and it is none the worse for the experience. It doesn't have any of HD's listed diesel designations.
Further, the manual says "At the first opportunity, see any authorized dealer to change back to 100-percent H-D oil." Boy, sounds urgent, dosen't it? If you don't hurry up and change, your engine will surely degrade before your eyes without genuine H-D oil in the crankcase. This strategy likely sells more overpriced oil, which makes stockholders happy, but is not firmly rooted in reality. The truth is that any 20w50 or 15w50 motor oil will run fine in your H-D in an emergency or otherwise, even mixed with other brands--synthetics of course providing additional advantages over fossil for long-term use. I broke-in my SG in with Castrol GTX, an excellent fossil oil, after 500 miles on the factory install, and it is none the worse for the experience. It doesn't have any of HD's listed diesel designations.
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Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
RE: WHICH OIL-API Gasoline or Diesel?
Kind of interesting that iclick used the brand of oil that performed the worse on the "infamous" Amsoil comparison.....
http://www.amsoil.com/lit/g2156.pdf
and his bike is still running!
http://www.amsoil.com/lit/g2156.pdf
and his bike is still running!
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2nd Gear
Joined: Feb 2013
Posts: 6
Likes: 0
From: Morgan Hill, CA
I would agree with iclick and am also a little skeptical. It would seem HD must know the API they recommend and sell. Not publishing those API's tend to smell like bs, look like bs, and in fact, are most probably (bs). It is interesting they suggest the diesel API's. Could be due to a heat problem but I have no facts to back that up. I wonder if one could go in a backdoor at HD and get the straight scoop? vernv