Hello Chris, I am working my way through a 5 litre can of Silkolene Rhino which is a 140 SAE gear oil. There are other makes available but you do need this grade. Dribble the oil in through the large cap until it comes out of the level plug designated 3098 on the drawing of the gearbox on page 60 in The Book of the Scott. If you don’t have this it is the hex bolt on the centre line of the gearbox to the right of the kick start.Jeff.
