I have 15W Valvoline Synpower fork oil in mine because that what they had on the shelf in Halfords, its been OK and there was no measurable difference to what was in there before whatever that was. Never used the "Silky Glide" fork seals but have used Wemoto many times, never had any issues with anything they've supplied and its always been of a good quality. If I was in the market for fork seals Wemoto or M&P would be my first port of call.