I was always told not to use synthetic on a break in because it does not allow the rings to seat well. Basically it never get's fully broken in. Also I believe the newer T-dub runs on 20W50, or at least mine does and its an 06.
Depends on the engine, but the TW's old-school technology does need dino oil to break in. I'd change at 20, 100, 600, and 1500 miles, switching to synthetic at 1500. I'd change again at 3000 so it would be easy to remember an oil change due every time the thousands is divisible by 3.
I've made some changes in the oils I use due to major changes in the grading and classification systems. I've alluded to these changes over the past year or so. Here's the low-down:
Only two grading.classification systems are relevant to TWs, and any other Japanese motorcycles with combined sumps, wet clutches, and flat tappet valve trains.
The first of the two grades/classifications that matter are viscosity numbers that are assigned by oil characteristics related to temperature according to the Society of Automotive Engineers (SAE).
These SAE grades are critical to proper oil flow properties at specific engine temperatures. Too high a viscosity, oil will not flow adequately when cold. Too low a viscosity, oil will not maintain a protective layer between metal components when hot.
There are 5 critical oil viscosity numbers recommended for the TW.
10Wxx cold start protection down to 14*F (-10*C)
20Wxx cold start protection down to 41*F (5*C)
xxW30 adequate heat protection to 95*F (35*C)
xxW40 adequate heat protection to 113*F (45*C)
xxW50 adeguate heat protection to 122*F (50*C)
10W30 14*F to 96*F -10*C to 35*C
10W40 14*F to 113*F, -10*C to 45*C
10W50 14*F to 122*F, -10*C to 50*C
20W40 41*F to 113*F, 5*C to 45*C
20W50 41*F to 122*F, 5*C to 50*C
Choose a multi-viscosity oil based on the temperature where and when you ride. No straight viscosity oils are appropriate for a TW.
The second vital grade/clssification is determined by the Japanese Automotive Standards Organization (JASO). These grades are critically important to motorcycle oils.
JASO T904 relates specifically to appropriate for wet clutches. DO NOT USE ANY OIL NOT MARKED "MEETS OR EXCEEDS JASO MA" or "MEETS OR EXCEEDS JASO MA2" in any motorcycle with a wet clutch. The JASO standard is the only standard that designates compatibility with a wet clutch.
Some of you swear by Rotella diesel oil. Fine and dandy, as long as the version and viscosity you use is Rotella T Triple Protection in 15W40. It is the only Rotella version that is in our viscosity range and that meets JASO specs for wet clutches. None of the 10 other types and viscosities of Rotella meet the viscosity and clutch compatibility requirements. If you choose Rotella, make sure you get the correct version and viscosity.
So far there is no testing standard for the rate of shearing of oil molecules due to compression between gears. New cars and trucks, with their more advanced metalurgy and computerized machining process, are built to much closer tolerances than a TW. Therefore, these newer engines require smaller molecules, exactly the opposite of what a TW needs.
The following is what will mislead motorcyclists in choosing oils:
I know that the older TW owner and shop manuals state that Type SE/SF oils are required. Unfortunately, SE/SF specifications are 40 years old, so no longer valid. These Sx (S is for spark ignition) and Cx (C is for compression ignition) ratings are determined by the American Petroleum Institute (API) and relate to resistance to coking, sludge formation, and high temperature lubricity. In fact, later API classifications limit the amount of additives that protect flat tappet cam lobes and followers. API claims 100% backwards compatibility, but it just isn't so. Supposedly, some less polluting alternatives have been introduced to ensure backwards compatability, but many older engines running these new oils (rated API SM/ILSAC GF-4) have died premature deaths due to cam wear. In fact, this rating system by the API no longer applies to motorcycles at all. API classification can be safely ignored for motorcycles.
The International Lubricant Standardization and Approval Committee (ILSAC) is the new kid on the block concerning oil grading, but they are little more than an API dog-and-pony show. Their standards are focused on new automotive technologies and have absolutely nothing to do with compatibility with motorcycles. Their ratings can be safely ignored.
Synthetic vs. Dino:
Synthetic oil stocks consist of molecules of more consistent size and structure than dino oils. Motorcycles thrive on consistency. Nod to synthetics.
Synthetic oil stocks consist of molecules more able to resist extreme pressure (between the rocker and cam lobe, between the gears in the transmission) without breaking down. Nod to synthetics.
Synthetic oil stocks are not contaminated with micro-components that combine with condensation to form acids--the sole source of acid-forming micro-components is byproducts of combustion. Nod to synthetics.
How much difference does this really make? The factory-recommended oil change interval on the TW is 3000 miles. With dyno oils I noticed clutch dragging, hard shifting, and occasional false neutrals after just a little over 1000 miles, the degradation of performance was due to the oil breaking down from use. With synthetic, no change in clutch or transmission performance for 3000 miles, which means the oil is still doing its job after 3000 miles. I'm too chicken to push intervals back any further than that. Sure, synthetic costs twice as much, but look at the money I save on oil filters, not to mention more ride time and less wrench time. It's a no-brainer.
