REAR SUSPENSION FRONT ARM SHOCK - difference between HCR shock and M8 SP?

I was looking for differences between the '09 HCR, '08 M1000 Snopro, and '10 M8 Snopro shock specs, and near as I can tell all three use exactly the same part numbers throughout the assembly and all the shims are in the same order, but the 09 and 10 shocks use a different oil than whats listed for my 08 M1000. I can't find anything that says what the difference is, but the 08 uses oil that lists for $17 per qt, and the 09 and 10 use oil thats $45/qt.

The 08 M1000 SP and 2010 M8 SP shock are the same part number (1704-351), but the HCR shock is different. (1704-850) This is weird because it says that the 08 shock and the 10 shock use different oil. I'm assuming that the expensive oil has similar weight characteristics, its just superior in some way and supersedes the old part number as a like in kind replacement.

Can anyone shed some light on the difference? Why would they be a different part number if they have all the exact same parts and are assembled in the exact same order? Or could it be that the parts manuals I have are flawed in some way?

My old man is going to tear into one of his HCR's soon, so I should know at that point if there are any actual physical differences between the HCR shock and the others.

12.5 a quart isn't too bad, but itt would really suck to buy it 5 gallons at a time though!

boondocker97 said:

The new oil may be a heavier weight to try to reduce the bottoming. I know that good shock oil is expensive. The stuff they use at Performance Fix Racing here in Bozeman costs them over $250 for a 5 gallon bucket!!!

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I agree that a heavier oil would be a fine way to increase the damping, but there is no appreciable difference between my 08 M1000 and my 2010 M8. I blow through both shocks with ease. I just rebuilt the 08 M1000 shocks, so neither are worn out. They are the same in every appreciable way.

I don't own an HCR, but I have ridden them, and other than the stiffer spring, I blow through them at will as well. (the center shock)