fork oil
 

Ok i am thinking of changing my fork oil next month (read asking yc nicely :)) and im wondering what to use. I weigh about 11 stone and dont really rag it about. Sooo 10w or 15w? Also would that change if progressive springs were fitted?

Re: fork oil
 

I'm a similar weight to you probably about 12 stone actually (I'm only 5ft tall!) and I put hagon progressives in with silkolene pro 15w oil. I reckon 10w would probably be fine, 15 might be a bit hard. I think it depends on the brand though the viscocity (sp?) varies from brand to brand, don;t trust the label.

Re: fork oil
 

D'oh i managed to impuse buy some progressive springs last night on ebay.


So im thinking 10w oil. Any ideas if this is do-able without stripping the forks?

Re: fork oil
 

mix it together and do 12.5. your only a stone more than me. 15 will be too harsh, 10 too soft.... Had 12.5 in the black one originally before bambi mangled the forks. Have tried 10 and 15 since and have to say the one in the middle is perfect

Re: fork oil
 

twice the price tho?

Re: fork oil
 

I'm about 12st and have stiffer (linear) springs in my SK1S. I used Motul Medium 10W which I'm pretty happy with. With stock springs I'd tried thickening the oil to calm it down a bit but as everyone will tell you, it isn't the solution (springs/damping needs to be balanced).

Check the table here which compares a load of oils. As you'll see comparing viscosities at 40 and 100C they vary a lot depending on make, even for the same nominal grade. Ideally you're looking for a 40C value somewhere round 30-35 and a high VI number (viscosity not changing much with temperature).

I've used some Castrol synthetic 10W before and as you can see from the table it has a 40C value of 42cSt but a VI of only 150, so it starts off thick and thins out quite a lot, and it definitely felt like it and I wasn't too impressed.

I've been looking for some Belray HVI 10W to try if anyone knows of a source.

Re: fork oil
 

HMM interesting. i was hoping to just go with some 10w stuff. but now its not so simple. Would the progressive springs make a difference to the suitable oil weight? or would it be the same for the standard as it is the progressive springs.

Re: fork oil
 

10W for your weight will be best I reckon. I have just put 15W in mine and I'm 13.5 stone without gear plus some 2up work.

Re: fork oil
 

Either will be an improvement :-P

You will get silkolene down at ace motor factors, or putoline at halifax motorcycle services.