I recently acquired a 1995 JT35. http://www.gasgasmotos.es/image/motos/1995_contact_jt_35.jpg GasGas http://www.gasgas.com/tech.htm recommends 650cc of 5W30 which seems to be difficult to find in a non-synthetic JASO-MA certified version. GasGas is also quite specific not to use Synthetic oils in the transmission/clutch. Modern synthetic motorcycle oils are not recommended in trials bikes which demands a lot from the feel of the clutch. I'm hesitant to try a 5W30 motor oil with friction modifiers designed for automobiles. I run ATF-F in my 2003 Pro, as recommended for the 'Pro' motor; but I don't think ATF-F is appropriate in the older motor. The GasGas JT35 motor is similar to the older GT Contact, and used in the JTR/JTX/TXT and Edition line all the way to 2004, with a similar design used by Sherco till 2009. Absolutely bullet-proof engine with the first 4 gear ratios for trials, and 5th/6th for trail riding. Sam engine design was adopted into the GasGas Enduro and MX engines from the mid-'90s to present. Any recommendations for a 5W30 Dino oil without friction modifiers? BTW - On my GasGas EC300 I run 900cc of Rotella T(15W40) as recommended for the Rekluse clutch.