Time to change the fork oil on the 2017 Sherco Factory. My bike has the 39mm diameter aluminum-stanchion rod Formula Tech forks. This thread includes specs for the steel-stanchion rod forks. Steel is stiffer, so the inside diameter of the stanchion rods is bigger on the steel forks. The fork spring is larger in diameter on that fork, and there is a little more internal volume, affecting the bled and collapsed oil height spec. I read Formula's PDF oil change docs. One is for the right fork (cartridge/rebound side), and the other is for the left fork (spring/compression side). The documents specified volumes & heights for the steel-stanchion forks: Left-Cartridge-Rebound ~250cc, then adjust by bled & collapsed oil height in the tube = 55mm. Splat Shop UK says the spec for the aluminum-stanchion fork is 75mm. Right-Spring-Compression ~250cc, then adjust to bled & collapsed oil height in the tube = 110mm. Splat Shop UK says the spec for the aluminum-stanchion fork is 130mm. The Formula documents call for 5-weight fork oil, which isn't an accurate spec. Splat Shop UK says the oil used by Formula is 3.47 centistokes (cSt) at 100 degrees C and 15.02 centistokes at 40 degrees C (which is about as hot as forks ever get). Viscosity Index (VI) is reported to be 106. The above converts to 41.6 Saybolt Universal Seconds (SUS) at 100 degrees C and 78.3 Saybolt Universal Seconds at 40 degrees C. Splat Shop says the closest oil they have found to this is the all synthetic ipone 3 weight fork oil: By the way, a handy viscosity converter is here, last line in their conversion table. http://www.widman.biz/English/Calculators/Metric.html Maxima's Racing fork oil in 5 weight is 85-150 SUS, which is thicker. What have been your experiences with changing from factory to whatever fork oils? Have you noticed and slowing when using the so call '5 weights?'