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09 Dyna Super Glide
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I run Red Line oil products in my 2009 FXD. Not being one for the 'one oil in three holes' concept, I use V-Twin Primary Case Oil in the primary, V-Twin Transmission Oil with Shockproof in the transmission and 20w50 motorcycle oil in the engine. The FXD just turned over 40k and runs great. I could end this post here and my bike would be no worse for it.

What I would like to find is a good quality motorcycle engine oil that does have the additives in it for the clutch and transmission that are found in every motorcycle oil that I have been able to find. The 'one oil in three holes' concept means that such oils are a compromise. They are not optimized for for a specific task. Instead they have additives that keep them from being too slippery and causing the clutch to slip as well as additives that resist shear forces that occur when gears in a transmission are in contact with each other.

Engine oils don't need such additives and are degraded by adding them. That reason that such oils even need to exist are mostly metric bikes where the engine, clutch, and transmission share a common sump. In these bikes there is no such thing as 'engine oil' or 'primary oil' or 'transmission oil.' It is a case of one oil for one hole.

My FXD is capable of using three separate oils that are optimized for specific functions - engine, primary, and transmission. Finding specialized oils for the primary and transmission is easy. Finding an oil that is optimized for the V-Twin engine has proven to be much more difficult.

I don't understand why the companies like Mobile-1 and Red Line don't make such an oil - a motorcycle engine oil without the transmission and clutch additives that are not needed in Harley engine oil.

I read that Lucas makes a 20-50 engine oil without clutch or transmission additives that says that it is good to use in V-Twins.

I just don't understand why Harley riders have to use oils that are designed primarily for metric bikes.
 

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Question:
Using Mobil 1 15W-50 in Harley-Davidsons
Several independent tests have shown that Mobil 15W-50 is virtually similar to Mobil 1 V-Twin 20W-50 oil. Since Harleys utilize separate oil supplies for the primary and tranny, is there any valid reason not to use the 15W-50 in a Harley?
-- Dave Gartner, Goodyear, AZ

Answer:
As long as the primary and tranny are separate sumps and there is no concern for clutch performance, then Mobil 1 15W-50 can be used in a Harley.
https://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Mobil_1_15W-50_in_Harley-Davidsons.aspx
....
 

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i agree, but because r/l makes the 20x60 motorcycle oil, i'll stick with it. eng temps make it a necessity, esp. if you frequently get caught in traffic.
 

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Back in the mid 90's they changed all of the oils of (I think 10w40 and less, I know 10w30 and less), they are marked in the API circle on the back as "energy conserving", they added an additive package of friction modifiers, this is good for a liquid cooled internal combustion engine, it is not good for wet clutch packs. However I have only seen one clutch failure with this oil in the tranny (Yamaha Royal Star), not 100% sure it was the oils fault.

Oil weights that are greater than 10W40 are NOT marked as energy conserving. Motorcycle specific oils that are 10W40 are not marked as "energy conserving". Your 15w40 weight oils have additive packages that are better for wet clutches, these are used in a lot of tranny's behind a diesel engine. Most people think that the 15w40's are a diesel specific oil, it's not the "HDEO" on the bottles/jugs stands for "Heavy Duty Egine Oil" and is rated for gasoline engines, (read the bottle).

As for a tranny lube (Gear Oil), the numbers (for example) 75w140, they do not mean the same thing as the numbers on a quart of oil. (I don't remember what they mean)

All engine oils shear down while being used, most 10w40's will shear down to a 10w30, and using engine oil in a manual tranny will shear it down even quicker.

Look on the back of any quart of oil, it will have an API circle on the back, that circle contains a world of information. The exceptions to this is the cheap dollar store oils made for vehicles prior to (I think 1988 or 1986) it could be older than that.

With all this said, no engine oils in my tranny, and only 15W40 or 15w50 in a wet clutch system.

My logic is any thing that makes an internal combustion engine really slippery cannot be good for a friction operated clutch. And a manually operated tranny is full of gears and needs a gear specific lube. I am not a genius and all of the above has worked for me for a lot of years. Use what works for you and keep us posted.
 

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I have 83,000 on mine. I switched to mobil 1 15-50 in all three boxes after my 5,000 mile dealer check up. It's not that hard of a decision, just change and ride. I still have my original clutch primary chain and no tranny issues. I had a lifter fail at 53,000 miles of abuse, but Harley does recommend changing at 50,000, so,,,

My bike is a stage 4 I don't baby it.

Best price I found for mobil 1 15-50 is a thiesons farm supply. $6.40 a quart.
 

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Harley engines, being almost entirely needle, roller and ball bearing, are really not hard on oils. Only the heat issue, because of being air cooled presents any challenge for engine oil. Modern synthetic oils of almost any weight will provide excellent protection. However the Harley lifters are a little leaky, and can make some noise with lighter weight oils.
 

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I had a Vulcan which only has one hole like all jap cruisers and the oil takes care of motor, tranny and clutch. Its been that way for years. No need for three diffrent fluids. The synthetic oil today for bikes can more then handle any need. Why Harley even has three seperate boxes amazes me. I just put Syn3 in all the holes on my 2010 Electraglide

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I had a Vulcan which only has one hole like all jap cruisers and the oil takes care of motor, tranny and clutch. Its been that way for years. No need for three diffrent fluids. The synthetic oil today for bikes can more then handle any need. Why Harley even has three seperate boxes amazes me. I just put Syn3 in all the holes on my 2010 Electraglide

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The reason Jap bikes use the common sump for engine, trans and clutch is it is a compromise.

Do Jap cars use the same oil for engine and transmission?
 

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The reason Jap bikes use the common sump for engine, trans and clutch is it is a compromise.

Do Jap cars use the same oil for engine and transmission?
Not a compromise, if designed from the get go for motor oil. And yes, some Japanese cars use 10w40 motor oil in the transmission and final drive. Also big over the road trucks use 20w50 motor oil in the transmissions.
 

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The reason Jap bikes use the common sump for engine, trans and clutch is it is a compromise.

Do Jap cars use the same oil for engine and transmission?
Jap cars also dont use 20w50 v twin synthetic motorcycle oil either. Its not a compromise, its called updated engineering. How about all the other bike companies using oil sump pumps. I love my 2 Harleys but you cant knock the engineering behind metric bikes.:loco
 

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Jap cars also dont use 20w50 v twin synthetic motorcycle oil either. Its not a compromise, its called updated engineering. How about all the other bike companies using oil sump pumps. I love my 2 Harleys but you cant knock the engineering behind metric bikes.:loco
It is a compromise cause gear oil has additives in it formulated for extreme pressures present in gear on gear applications. No amount of "engineering" does away with this kind of pressures. It's the nature of using the gears in a transmission to generate acceleration of a vehicle.

Engine oils and gear oils both have anti-wear additives,
and they both must lubricate, cool and protect components,
but gear oils are placed under extreme amounts
of pressure, creating a propensity for boundary lubrication,
a condition in which a full fluid lubricating film is not
present between two rubbing surfaces. For example,
differentials in cars and trucks have a ring and pinion
hypoid gear set. A hypoid gear set can experience
boundary lubrication, pressures and sliding action that
can wipe most of the lubricant off the gears. To combat
this extreme environment, extreme pressure additives are
incorporated into the oil.
http://www.bestlubeusa.com/gearlube.pdf

Just because you can use a motor oil in your transmission, it doesn't necessarily mean that motor oil is the best choice available.


My Harley's oil pump sumps the oil out of the crank into a remote reservoir.... not sure what you're getting at on that....
 

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Designing does change the way transmissions need oils. Most motorcycle transmissions and final drives are straight cut gears, with very light loading, not bevel or hypoid gears, requiring extreme pressure oils.
 

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Hi, before ending the guarantee I threw a SYN3 .... mineral oil for 3 holes .... so I was advised by the dealer, here in Italy. The SYN3 not like. oil of low quality. Rate noisy. engine oil after 2000km was exhausted and mechanical noises increased. I solved with Spectro oil. 6speed for trans and Platinum 20w50 heavy duty motor. A fairy tale! Trans seems to Japanese! ;-)

Cava
 
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