Yep, I haven't changed the oil yet but I think with the fixed rebound (and compression) valving on the forks, going to a heavier weight oil will help counteract the increased rate of extension (due to more pre-load) and slow down the increased rate of rebound. Should then bring it back towards the standard rebound speed of movement. It will also slow the rate of compression and subsequent weight transfer under braking. The only thing to watch out for is the forks 'packing down', where the springs can't extend properly during use because the rebound damping force is too great for the spring extension strength to overcome, when it is taking multiple compressions. Normally this happens off road only.

Another problem with fork springs that are too soft, is that when you are off road is you can get the feeling that it is too stiff by getting poor front grip and harsh feedback through the bars. What is actually happening is the forks are blowing through their range of movement and you are effectively bouncing off the internal bump stops and the springs are becoming a 'solid' link. I have had this on a GasGas Enduro bike and didn't believe it until I had the suspension set up by Chris Hockey. A top bloke and international standard enduro rider. If I get serious on the off road with the Tenere, I'll be paying him a visit first!