Since Harley's are not wet clutch, and it calls for 20w50, is there harm in using automotive 20w50? I know it calls for a Diesel rated oil, but what's the difference in regular automotive oil and the "V- Twin" oil that is not Jaso MA?
Harley’s are wet clutch. The engine, tranny and primary are all separate.Since Harley's are not wet clutch, and it calls for 20w50, is there harm in using automotive 20w50? I know it calls for a Diesel rated oil, but what's the difference in regular automotive oil and the "V- Twin" oil that is not Jaso MA?
Since Harley's are not wet clutch, and it calls for 20w50, is there harm in using automotive 20w50? I know it calls for a Diesel rated oil, but what's the difference in regular automotive oil and the "V- Twin" oil that is not Jaso MA?
I hear you on price but just filled my '19 Suzuki S40 with Mobile V Twin 20W50 and it cut mech noise noticably. Next the trans has balked at fifth gear from day one now goes in so slick I'm hunting the next gear thinking I haven't hit 5th yet. I've never been a fan of mobile 15W50 (tried it couple times other bikes) but I'm sold on this stuff. YMMV30k miles on my '01 RK using M1 15-50w in its 88 motor. No oil issues. The V twin branded oil is way overpriced IMO.
If it works better than go for it. HD was recommending their motor oil in the trans. Their fits all hole's oil. Not me.I hear you on price but just filled my '19 Suzuki S40 with Mobile V Twin 20W50 and it cut mech noise noticably. Next the trans has balked at fifth gear from day one now goes in so slick I'm hunting the next gear thinking I haven't hit 5th yet. I've never been a fan of mobile 15W50 (tried it couple times other bikes) but I'm sold on this stuff. YMMV
I say this is good advice. Years ago I used Mobil 1 15-50 in my 88 and 96 engines. It did fine and gave good analysis reports. My concern today is with the 15-50 changed to meet SN and SP standards, it's not as stout in regards to an aircooled V twin. Today I would only use a 20-50 oil.Harley has been wet clutch for a long time now, but the primary drive is separate from the engine, so this is not an important consideration in selecting an engine oil.
I've rebuilt and repaired more HD engines than I can remember, I do my own machine shop work, and the failures due to using inferior engine oil are pretty easy to see when you pull the engine apart.
As many have pointed out here in this thread and elsewhere on this forum, some regular automotive 20w-50 will work just fine. And what I want to try to address here directly, is that some will not, and I want to try to explain why in a way that is useful.
If you go back far enough in the HD shop manuals you will see that Harley used to specify low-ash / high-detergent oils, and while they didn't address this directly in the shop manual, the presumption was also an oil that did not foam up and an additive package that was suitable for roller or flat tappets and fairly steep cam profiles.
I'm guessing here, but I think it was some time in the late 1970s we suddenly noticed that the oils which used to work just fine (like Castrol GTX 20w-50) suddenly were not working anymore, especially in regards to the service life of cams and rollers. The crank pin bearings were holding up OK, the cylinder walls were doing OK, the valve stems were doing OK in cast guides, but the hard facing on the cams and rollers was failing early, especially on high-lift cams, steeper cam profiles, or with weak valve springs -- anywhere the roller could bounce or skid.
I always wondered about this, and from what I've read here, it appears that some automotive oils got a different additive package because of catalytic converters. And those oils stopped working in Harleys.
Most riders don't put enough miles on their bike to know the difference or care. You'll read many people here going on about how many years they have been riding, I'd be more interested in how many miles under what conditions. If you are putting on serious miles under adverse conditions, the oil really does matter.
So it's not a yes or no question -- like many others here I have run Valvoline VR-1 in an older Harley (several Shovelheads) for a lot of years and they did just fine. They all leaked so bad they always had some amount of fresh oil.
In a newer Harley (Evo or later) I wouldn't even consider running an oil that wasn't formulated for V-Twin. There is a difference, and the cost of the oil is nowhere near the cost of the rebuild.
There are others here who can address the chemistry difference in the oils far better than me, so let's take a minute and look at the differences in the engine, which is something that I can address and might be helpful in understanding why I take the position that I do about V-Twin formulated oils.
When Harley first started recommending 20w-50 oil I was working at a dealership, and the factory guidance emphasized that every 20 degree increase in temperature past a certain point cut the oil life in half, so it was critically important to use the right oil in the first place and to observe the recommended OCI.
A lot of bikes these days are water-cooled, if you think about what this means for the oil, the temperature in the engine is relatively predictable and stable.
Not so on a Harley (at least until recently) -- a "normal" head temperature on a bike being run hard on a hot day can get quite high. There's oil in that head, and that oil is getting very hot.
Harleys are not just air-cooled, strictly speaking. They were also explicitly regarded as oil-cooled b by the factory school. You want an oil that is formulated to take the heat. Someone mentioned oil splash on the bottom of the piston domes, this really is important to think about, again, the engine is not water-cooled and those pistons are getting hot.
For this reason the "low-ash" specification really is quite important for Harleys. I can't emphasize this enough, the low-ash specification is there for a reason, and I don't know this for sure but I suspect this is at least part of the reason why HD says to use HDEO if their specified oil is not available.
With all of that and a gear-drive oil pump, you also really don't want an oil that foams up.
In addition to the potential for cam problems (I suspect from not enough zinc) and very high head temperatures, Harleys present additional lubrication challenges, perhaps not entirely unique, but to a greater degree than other motorcycle engines.
The piston speed on a long-stroke engine like a Harley is comparatively high halfway through the stroke. Not all oils are up for this.
Harleys have roller-bearing bottom ends, they are incredibly tough assemblies, but this is a different kind of lubrication requirement than what's happening at the valve quides, the piston skirts, or the cams. I have disassembled Harleys that have been run on suitable oil and I have measured wear at the big end of the rods at more than double the service wear limit and the metal still looked great -- no scoring, pitting, chipping, no visible damage whatsoever, the engine was just worn out.
I have disassembled engines that were run on the wrong oil and it's just sad to see the amount of metal missing out of the big end of the rods and the crankpin. There's no reason for it other than trying to save money on oil or not knowing any better or both. And there is no way to mistake the fact that the damage was from lubrication failure due to using the wrong oil.
Free advice, possibly worth what you paid for it, no doubt we'll get some replies from people who were not in logic class the day they covered the fallacy of the undistributed middle, but maybe this helps a bit. I hope it does.
I have been buying JT-8 15W-50 in 5 gallon buckets lately, $79.00 on sale. Between my Son and I, we maintain 4 HD bikes. I also used this oil in shared sump bikes with no issues.As @Brian553 mentions I use Mystic JT8 15/50 faithfully for almost 8 years in my 2014 Road King and continue to this day, the first year I used Harley oil.
I have a ton of UOAs on it in this forum.
I often wondered why Harley calls for a Diesel oil if Harley oil can not be bought (and as another in here points out to me all the time, change back to Harley oil asap)
I suspect simply is because Harley oil is formulated more like a HDEO (diesel/gas rated oil) Why? I dont know but I do know its not about the anti-wear additives as Harley oil doesnt have a large amount of that either (more on that in a minute)
I suspect maybe being formulated as a diesel oil which is typically about engine cleanliness is the reason HD calls for it.
HD engines run at high oil temps 245 to 260 at 80 MPH for more than 30 minutes at a time and I think they are more concerned about piston and piston ring deposits which in itself leads to engine wear.
The bottom of the pistons of a Harley are sprayed with oil at high speeds to cool the pistons. (Im sure other bikes that use regular oil too) Diesel engine combustion chambers also run at high temperatures. Anyway, I think it's about engine deposits. Whether I am right or wrong doesnt matter but I put my faith in Harley knowing more than I do and I follow the Manual. After all I paid over 20+k for the bike, why wouldnt I trust their recommendations? Now at almost 9 years old it's never needed a repair, never.
With that said, in this forum is also a UOA as I did run Mobil 1 15/50 for one oil change to see how it would do. I figured at least Mobil 1 at one time (or still does) hold an obsolete HEDO rating of C and lets face it, I am SURE its a find choice.
Anyway, the UOA I posted in here clearly shows GREAT wear numbers, in addition I am not sure but I thought MAYBE the oil ran just a few degrees cooler but not really confirmed as I only ran it that one time, even with the great wear numbers.
Here is why I didnt use it again, I ride in REALLY HOT weather, typical summer time temps easily above 90 degrees everyday I ride in the summer. The full synthetic Mobil 1 15/50 would get a little noisy, engine would sound a little funky at times, nothing terrible but just different. I sure it was fine but Im supposed to feel better about a non recommended oil and I didnt! *LOL*
There is one unknown here about that noise, I also was using a different oil filter, of all times to be doing that ... oh well.
This is not to say I will never use Mobil again if I cant get the Mystic JT8, now that I moved from the midlands of SC to the coast of NC and temps will be cooler plus I will no longer (maybe) be running up to 85 MPH on the interstates anymore.
However, buying JT-8 in the 2 gallon jugs is convenient and I also use it in our Chaparral Boat.
Ok, now on the anti-wear additives that many for some reason seem to think is the benchmark of a quality oil. I never understood that thinking. The best anti-wear agent is the oil itself. A properly engineered engine should not have to rely on anti-wear agents to protect in the absence of lack of lubrication.
One other knock on anti-wear agents, they lead to piston ring and piston deposits. For anyone who doesnt know, moly is also a metal.
Im sure many in here are aware some piston aircraft oils from Shell, in the same weights that we use for motorcycles have no antiwar agents because .... piston deposits.