But read this also:

SCREAMIN' EAGLE® SYN3 SYNTHETIC MOTORCYCLE LUBRICANT

What are the key benefits to using SYN3? SYN3 Lubricant:
Can be used in the engine, primary chaincase, and transmission.
Offers improved film strength for superior wear protection at high temperature, and improved deposit control for a cleaner engine, transmission, and primary chaincase.
Is formulated for reduced oil consumption, improved wear protection, high temperature detergency, and superior overall field performance.
Provides high temperature film strength, which means the lubricant maintains film thickness in high power output and high engine speed conditions, keeping the metal parts from rubbing against each other and resulting in less wear.

In the past, Harley-Davidson® did not recommend the use of synthetic oils in H-D/Buell® motorcycles. Why is H-D introducing a synthetic now? Because Harley-Davidson cannot test and certify all available synthetics on the market nor control their oil and additive formulations, we have discouraged their use. However, Harley-Davidson, in close partnership with our suppliers, analyzed available petrochemical technology and developed a custom-blended candidate fluid that can be used in all three cavities of a Harley-Davidson/Buell motorcycle. This product has been exclusively designed for Harley-Davidson and is the only synthetic product TESTED and CERTIFIED by Harley-Davidson engineering for use in H-D/Buell motorcycles.
What kind of testing was done on SYN3? Over three years of laboratory bench testing, dynamometer testing under accelerated conditions, open road vehicle durability testing, closed course durability testing, and wear and deposit rating analysis was conducted on SYN3.
Who makes or blends this product? SYN3 is a proprietary blend, exclusively custom-blended for Harley-Davidson.
Will H-D 360 Motorcycle Oil be replaced by SYN3? Harley-Davidson continues to offer H-D 360 Motorcycle Oil. SYN3 is an alternative lubricant product from Harley-Davidson, and in particular, a formula that is very effective for high performance engines and hot climate applications.
In which motorcycle models can SYN3 be used? SYN3 is formulated for use in Harley-Davidson Evolution® XL, Evolution 1340, Twin Cam® (all displacements) and Revolution-equipped models and all Buell® models.
Can SYN3 be used in ShovelheadTM engines, 4-speed Big Twin transmissions, and early Shovelhead 5-speed transmissions? Harley-Davidson did not test SYN3 in these engine configurations. There are a multitude of tests that must be completed before a lubricant can be certified for use in Harley-Davidson engines, primary chaincases and transmissions. Many of these tests require that the components be brand new, and the required quantity of new powertrains for testing and validation could not be procured.
Will the use of SYN3 lengthen my service intervals? No, we recommend that you still follow your owner's manual for the proper service schedule for your vehicle.
If this product is a high performance lubricant, why would my service intervals not be extended? While SYN3 will help reduce the amount of impurities to your engine, no lubricant product can reduce fuel dilution (this happens every time you start your vehicle). As a result, the regular service schedule is recommended for optimum performance of your vehicle.
Lubricants begin to break down the moment the engine is started. The long molecular strands of the lubricant begin to be sheared between the faces of gears, pistons or other moving parts. SYN3 was tested to confirm that the lubricant provides the protection required for the engine, primary chaincase and transmission for the drain intervals specified in the Owner's Manual.

A common concern with other available synthetic oils is that roller bearings may "skate" or "float" in the bearing race, and not actually rotate as designed. How does SYN3 prevent this from happening? SYN3 was formulated to provide improved high temperature stability, shear stability, proper lubricity for anti-wear (without roller bearing "skate" or "float") and maintain the coefficient of friction for proper clutch operation (without clutch slippage).
Harley-Davidson does not recommend any lubricants that have not been tested and approved by Harley-Davidson engineering because we do not control the formulations. Lubricants are reformulated frequently to meet changing American Petroleum Institute (API) Ratings. API Ratings are developed and tested for use in water-cooled automotive engines and diesel applications. There is no API Rating (classification) for Motorcycle Engines.

Harley-Davidson, in close partnership with our suppliers, analyzed available petrochemical technology and developed a custom-blended candidate fluid that could be used in all three cavities of a Harley-Davidson/Buell motorcycle.

Can a brand new bike have its fluids drained and refilled with SYN3, without voiding the warranty? Yes, this product can be used as a first fill upon delivery of a new motorcycle. The formula is approved by Harley-Davidson for use in all stages of engine life and is not detrimental to the engine break-in cycle.
Do the cavities that are going to be filled with SYN3 need to be completely drained? Yes, the cavities that are to be filled with SYN3 must be completely drained. It is not recommended to mix SYN3 with other lubricant products. During servicing, a residual amount of fluid will remain in the sumps. It is not required to "flush" out the residual fluids.
Should I put a can of additive in with each oil change? No, SYN3 is blended with an additive package already included. Other additives are not needed and may not be compatible with SYN3. In fact, oil additives may actually dilute the SYN3 formulation.
If I'm on the road, and realize I'm down a quart of engine oil, and cannot buy SYN3, what should I use? If SYN3 is not available and addition of motor oil is required, the first choice would be to add H-D 360 SAE 20W50 to the SYN3 for engine lubrication. Although H-D 360 is compatible with SYN3, we suggest the mixture of the fluids be changed as soon as possible. If H-D 360 is not available, the second choice would be to add an acceptable diesel engine oil as listed in the Owner's Manual, and again we suggest the mixture of the fluids be changed as soon as possible. DO NOT add diesel engine oil to the primary chaincase or transmission.
Can a quart of oil be added to the Primary Chaincase or Transmission when SYN3 is not available? If SYN3 is not available and addition of lubricant to the Primary Chaincase (Evolution 1340 and Twin Cam 88) is required, the first choice would be to add H-D Primary Chaincase Lubricant. Although H-D Primary Chaincase Lubricant is compatible with SYN3, we suggest the mixture of the fluids be changed as soon as possible.
If SYN3 is not available and addition of lubricant to the Primary Chaincase and Transmission (common reservoir) for Evolution XL and all Buell models is required, the first choice would be to add H-D Sport-Trans Fluid. Although H-D Sport-Trans Fluid is compatible with SYN3, we suggest the mixture of the fluids be changed as soon as possible.

If SYN3 is not available and addition of lubricant to the Transmission (Evolution 1340 andTwin Cam 88) is required, DO NOT ADD H-D Semi-

I think you might mean SUNOCO? Or is CITGO and SUNOCO the same thing these days?

In a pinch any brand oil is better then no oil,eh?

Been doing some research on Amsoil, also talked to a couple mechanic freinds of mine that own their own shops, Like serious off road shops. Another is just a regular car shop They all say Amsoil is by far the best. Now thats coming from guys that tear sh.t down for a living and can see the results of many different oils
I've been following the manual but talking to them I might be stearing away from the real OEM Oil and move towards Amsoil

I spent a little time trying to find a MSDS online, but could not find one. I should be able to get one from the dealer. I do my best to support the MOCO, but if it is Citgo, then I will consider other oils. I support the brand, but I wish they would stick with the made in America idea. Some of their clothes are not made in America. I want high quality, made in America OR made somewhere which they do it the best, but not china. Why not sell lil Joe's leather?

I spent a little time trying to find a MSDS online, but could not find one. I should be able to get one from the dealer. I do my best to support the MOCO, but if it is Citgo, then I will consider other oils. I support the brand, but I wish they would stick with the made in America idea. Some of their clothes are not made in America. I want high quality, made in America OR made somewhere which they do it the best, but not china. Why not sell lil Joe's leather?[/quote]

100% agree with you, we all have to be careful not to fall on our own sword in the name of brand loyalty

I have not seen any clothing at harley American made for 20 years, a lot of the parts on that American made motorcycle are from Japan Italy and a lot of other countries I don't know, and today China is probably there also. some day take that american made motorcycle apart and look closely at the componets, it is a shame how many are from foreign countries. My first willie g leather was Hein Gerick, made in germany I believe and that was 1984
Deerslayer

I think we all love our bikes and have some loyalty to the company that made them. When I do my research - I look for quality and value. A lot of times the moco just plain costs more than its worth.

If I go Synthetic I'm leaning towards Amsoil, but for those of you that do not here is what I like to use,....A 40 year HD Shop, Highway Choppers in Glendale, AZ. Reccomends The Aviation Engine Oil AeroShell 100 / SAE50 and AeroShell 120 / SAE60 for driving here in Phx. In the manual for my 2007 Road King 96Cubes it calls for oil SAE in relation to starting temps. 60 degrees and above SAE 50W....80 Degrees and above SAE 60W For us former Military you will like that the AeroShell actually has a Mil Spec MIL-L-22851D Here is what it states on the back " AeroShell Oil is an ashless dispersant single grade oil that provides superior protection in 4 cycle aircraft piston engines in normal operations It is fully approved for SAE J -1899 I guess my point Made in CANADA by Shell Canada Products, (An Oil Company) I don't think you can get a better non syn oil than this aviation oil, just wanted to throw it out there for the non syns like myself

I have always believed that motorcycle oils are different from auto and aircraft. Just because it is a great oil for airplanes does not make it a good oil for Harleys or autos. Good luck