Looking at Peter Verdone's chart, you can quickly determine the 10W, 15W, oil weight designations from the sellers can't be trusted, since one vendor's 5W oil might have the same viscosity as another vendor's 10W oil.
http://www.peterverdone.com/wiki/ind...spension_Fluid
Also, one shouldn't completely trust the chart, either, since the viscosity of a particular brand of oil might change. The only sure way to determine viscosity is to read the product data sheet (PDS) or the manufacturer's safety data sheet (MSDS) for each individual oil. For example, the Verdone chart lists the viscosity of Mobil1 Synthetic ATF as 34.0 with a viscosity index (VI) of 199.00. However, the PDF for this ATF at the Mobil website lists the viscosity as 36.3, with a VI of 176.
http://www.mobil.com/USA-English/Lub...hetic_ATF.aspx
For the forks in my other motorcycles I have installed Valvoline MaxLife Dex/Merc ATF. I chose this fork oil for several reasons. First of all, it has the lowest viscosity of any ATF I have researched.
http://www.valvoline.com/pdf/maxlife_atf.pdf
As an added bonus, this ATF had the lowest price. I bought the Valvoline ATF for $13.50/gallon at my local AutoZone store. Contrast this price with the cost of the "boutique fork oils."
Last year I changed the fork oil in three motorcycles in one month, using the Valvoline MaxLife Dex/Merc ATF, and I still have over a quart of ATF left over. However, I did use Showa SS-7 Fork Oil for the inner cartridge of my CRF250X forks, since the valving is designed for an oil with a viscosity of 16 cSt.
Most of the Dexron VI ATFs also have a low viscosity around 30 cSt, which is very close to the Valvoline MaxLife Dex/Merc. However, none of them could match the price of the Valvoline.
I chose Mobil1 Synthetic ATF for the forks in the RX3 because it has a higher viscosity than the Valvoline MaxLife Dex/Merc ATF. I wanted a higher viscosity of 10W for the RX3 forks, instead of the 7.5W provided by the MaxLife Dex/Merc ATF.
