In the delima of changing final drive oil.
do you use 10w 30 motoroil or do you use 75w90 gear oil.

Honda in the initial fill at the factory uses gear oil with a healthy dose of Moly added to it. This should be left in for an extended time to allow better protection during gear breakin. I leave it for 10k miles or at least the first season.

In looking at oil data for both I have discovered seveal things about oil
1. Motor oil and gear oil use different rating systems for properties.
One in particular is viscosity.
here is a chart that shows both both tests in one chart.
http://www.bobistheoilguy.com/visc.html

As you can see both 10w30 motor oil and 75w90 gear oil are both approximately the same.

2. Additives to each can be used to change the way the oil works.
both have additives which help prevent breakdown of the long chain hydrocarbons.

Motoroil has additives that keep wear and combustion particles in suspension to help prevent deposits (not a good thing for gears) and get them to the filter. They also have some additives which harm thrust washers in gear drives. ( I can't find that reference again)

Gear oil have a different additive package that is more conducive to the high pressure of meshing gears. they have EP additives to help it cling to gears when they mesh and not get squeezed out. Good thing.
http://www.ehow.com/about_5729620_hypoid-gear-oil_.html

3. Swing final drive is a mixture of straight cut gears and helical gears. Thus a "gear oil would be a better choice than motor oil In the right viscosity.
http://www.bikebandit.com/houseofmotorcycles/2005-honda-motorcycle-fsc600a-silver-wing/o/m15664

I don't have all my old references due to PC crash , but if you do your homework you can find them also. The refences I gave are just examples and maybe not the best for my discussuion.

The bottom line.
If you change the final drive oil regulary (set up your own schedule)
it should help keep your drive healthy for years to come.

MaxB (who uses synth gear oil in my final drives)

Max,

Thanks for the info. I used synth oil the first couple of times and the last time I used synth gear oil. I don't feel a difference but just thought it couldn't hurt. I know the subject of "oil" can raise some good discussions but I just think that changing it often is good no matter what. The final drive oil only takes about 10 mins and doesn't require the removal of any tupperware so I do it more than the manual says too.

(for those that haven't done this before) If you do it according to the manual I think they tell you to remove the covers but by using an open end wrench you can get to the plug without removing covers. There is a Pictorial on this too in the Pictorial section.

Thanks for the info.

What bothered me about the gear oil was the statement that some Japanese transmissions have phosphor bronze components that can be damaged by chemicals in gear oil.
I now agree with the statement that if Honda wanted a gear oil in the final drive, why didn't they spec one? Instead they spec a JASO MA motor oil.
Why, when they already sell a gear oil for the Gwing?

I went to the source. I called Honda support.
Motorcycle Division


American Honda Motor Co., Inc.
P.O. Box 2200
Torrance, CA 90509-2200
Mail stop: 100-4C-7B
Telephone: (866) 784-1870

And asked:
"Why does the Swing use 10w30 motoroil instead of gear oil like my goldwing and VTX?

After being passed around very courteously 4 times, (one sounded very sweet) I was told that uses a different type of transmission. Also that the drive uses the same oil as the engine (HUH????????????).

I told them it is a separate oil in the final transmission.

He said; "where did i find that in the owners manual?"

I said; It's in the service manual.

He said; The Swing uses different gears in the final drive than in My other two bikes.

he said ; honda recommends using 10w30 motor oil.

I said; thank you for your time. Hung up.

Conclusion:
1. i did not get a satisfactory answer to my question.
2. The Swing uses straight cut and helical gears, similar to my other bikes.
http://en.wikipedia.org/wiki/Gear

3. I do not think that the four people do not know gears or the reason and spouted Honda manual recommendation.
4. I had my reflex final drive transmission apart and it had a very similar setup , it used gear oil.
5. ???????????? I guess the drama goes on.

I will continue to use synth gear oil.
My local honda shop uses gear oil also.. are they wrong?

maxB (who didn't get a satisfactory answer as to why)

How much gear oil do you use?

.32 liters, 320 ml, .34 US quarts. on refill.
So a quart will last several changes. Unless you spill a bunch like I do. hahahaha

maxB

Knowing me, I'll probably end up losing half of it just putting it in the can!