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?
"V-twin" Oil
- Thread starter montero1
- Start date
You could use the Castrol 20-50 "classic car" as it has higher levels of ZDDP than would qualify for an API rated oil. I suspect they call for a diesel rated oil for that very reason.
I either run M1 15-50 or Rotella 15-40 in mine
I either run M1 15-50 or Rotella 15-40 in mine
I ran M1 15w50 in my Buell XB12XT
There is no harm, however, synthetic motorcycle oil blends use some pretty premium additives and basestocks and can take a lot of use and abuse. A lot of times the HTHS of V-Twin oils are very high--eg, Mobil 1 V-Twin is 5.8cst. That said, I think that Mobil 1 15w-50 is a smart choice for Harley's. Alarmguy has used Mystik 15w-50 HDEO for decades, and is sure to come in soon to convert you to it. It works well, too.
old pics, but of top end of 1995 Harley Evo that ran 15w50 synthetic
dont remember exact mileage but it was up around 160k. all on auto oi 15w50 Napa synthetic for th emost part.
bobistheoilguy.com
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Harley’s are wet clutch. The engine, tranny and primary are all separate.
There is no harm in using automotive specific oils. I ran Valvoline Max Life 20W50 for about 2500 miles in my ‘89 Evo. The UOA from Blackstone showed it was just fine.
1989 Harley Electra Glide. 2481 miles on Max Life 20w50
I bought the Max Life on clearance from Autozone for $1 a qt. I wanted to see how it would do on a run of 2500 miles. Black stone says it looks good except for thinning a little. I'm not a UOA expert, so you guys tell me what you think. I was using a Purolator L10241 filter. Here's the link to...
bobistheoilguy.com
30k 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.
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.
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.
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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 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 had a 1972 Moto Guzzi Eldorado with over 350,000 miles yes that's correct over 350,000 miles by using mobile one 15-50 the motorcycle is still on the road and probably has close to 375,000 miles I did put a Big Bore Kit in at 95,000 miles to get rid of the Chrome boards and make it into a thousand CC
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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 remember when HD said synth. oils would cause engine roller bearings to ''skate'' so don't use it. That went away when they started selling their own full synth. oils.
I ran the standard Harley 20w50 oil on my 96 Sportster for over 12 years, now I use Mobil ONe 20w50 motorcycle oil,,no problems....I would suggest using an oil thats rated for motorcycles....
2016 FLSS bought new
Ambient here runs 15 deg C up to 44 deg C
I had the dealer fit a factory oil cooler at 1st service. Had a good read of the handbook, as a result, i run straight 50 year round. The dealer was surprised, but there it was in the bible
I always do light load medium revs for the 1st 10 - 15 minutes. No probs, actually mine is the only bike in a group that doesn't single cylinder itself in hot traffic crawling situations
Ambient here runs 15 deg C up to 44 deg C
I had the dealer fit a factory oil cooler at 1st service. Had a good read of the handbook, as a result, i run straight 50 year round. The dealer was surprised, but there it was in the bible
I always do light load medium revs for the 1st 10 - 15 minutes. No probs, actually mine is the only bike in a group that doesn't single cylinder itself in hot traffic crawling situations
I use Amsoil I my HD,but...I’ve always meant to ask the penn grade 1 folks a question. Their 20-50 Mc oil is aprroved for wet clutches. Their high performance 20-50 is semi syn and has a better additive package that would seem better for a Harley twin cam?
I’ve used Valvoline Vr1 conventional 20w50 in my last three Harley’s, along with Redline Shockproof heavy in the transmission and Harley formula+ in the primary. Currently at 49,500 on my 2009 Superglide and it uses no oil and the transmission shifts like butta! 
I run ST 20w50 from WM. Under $17 for 5 quarts and it does just fine. I run gear oil in the transmission and Rotella 15w40 for the primary. It's all inexpensive and easy to find locally.
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.
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.
