Here’s a really nerdy table that uses the much tighter Centistoke (Cst) testing scale, so we can compare brands with accuracy. But, due to the international SAE standard being so loose, one oil company’s 5Wt can be the same viscosity as another’s 7.5Wt. So what oil should you use in your suspension? Most suspension units use approximately a 5Wt (SAE). I will use Opie next time I need fork oil, Tim, you are a top man.Buying the right oil for your bike is very important as it can effect performance and the amount of wear-and-tear your bike receives. The oil I supplied to Ernie turned out to have a viscosity of 47.4, no wonder it was bloody stiff. So as you can see from the figures above the W number bears no resemblance to the viscosity. Red Line Light Weight Suspension Fluid 16 I then set about finding others that were in the same range so I had a choice.įork Oil recommendations for the Yamaha FJR 1300A He came back again with a recommendation for Motul Light 5W Factory Line Motorcycle Fork Oil which has a viscosity of 18, so close enough for me. Telling him my aim was a viscosity of 19. His first recommendation was for any 5W oil until I pointed out that it was the viscosity that was the critical factor as the 5, 7.5, 10W etc bore no resemblance to the viscosity. I contacted Opie Oils for some advice and Tim (very helpful) set about finding me some suitable oil. Specially designed for any type of fork, upside-down (USD) forks or conventional ('right-side-up») forks. Motul tends to be a tad heaver and can give stock suspension a little more rebound adjustment. The Ohlins site however was more helpful giving a viscosity of 19 mm2 Centistokes 40° C. Ohlins is good but 35 a bottle and for stock suspension a little overkill. A US site tell me that Yamaha M1 is a zero weight oil but no viscosity figures. The Yamaha manual recommends Yamaha Suspension Oil M1 or Ohlins R&T43.īoth of which seem pretty scarce in the uk. The manufacturers W numbers bear no resemblance to the viscosity. I had already purchased the oil before I sent them off so Ernie put it what I had sent him. But, due to the international SAE standard being so loose, one oil company’s 5Wt can be the same viscosity as another’s 7.5Wt. They were stiffer than a stiff thing on a stiff day. The searching started when I took my first ride after fitting my newly sealed forks. Fork oil comparison chart Sept13. Motul Fork Oil Expert - medium Fork Oil 35.9 6 112Semi/Synthetic Motul Factory Line - medium Fork Oil 36 6.4 130100 Synthetic SHOWA SS-8 36.8 7.2.

So I suppose you could say I knew fork oil about fork oil. Viscosity Index Type Spectro SPL very light Shock Oil 26.4 9.9 400. Before I started researching fork oil I didn’t know much about it other than it was oily.

Motul fork oil viscosity chart