10w 20 Fork Oil

Wattie · Jun 27, 2020

I'm looking to change the fork oil on my 2002 trophy 1200, the manual says 10w 20 grade fork oil. I can only find one product that's a multigrade fork oil, it's called procycle and is made in Germany. I've never heard of it and none of the mainstream names seem to do a 10w 20, they are all single grades. Cost inc shipping is a reasonable £15 for 1 litre. However anyone got any other recommendations?
I posted it here rather than the trophy forum because it's the same recommendation for a few of the later T300 models not just the trophy and I thought others must have already done this. I've searched the forum for 10w 20 but no help.
Thanks

Wishbone · Jun 27, 2020

I may be wrong but I think it is either 10w or 20w fork oil?
Found this in another forum:
"The oil weight and levels changed over the years. Early models where 103mm/SAE 10. Then 117mm/SAE 10, then 117mm/SAE15, then 105mm/SAE10, then 133mm/SAE10W-20. For 1999 and above, 133mm/SAE10W-20. However, with factory springs, I recomend SAE15 and start at 125mm. The higher oil level will help reduce the nose dive under breaking do to less air in the forks(air compresses more than liquid-less air=less compression=less nose dive). Ideally, stiffer springs are in order."

Wattie · Jun 27, 2020

Wishbone said: ↑

I may be wrong but I think it is either 10w or 20w fork oil?
Found this in another forum:
"The oil weight and levels changed over the years. Early models where 103mm/SAE 10. Then 117mm/SAE 10, then 117mm/SAE15, then 105mm/SAE10, then 133mm/SAE10W-20. For 1999 and above, 133mm/SAE10W-20. However, with factory springs, I recomend SAE15 and start at 125mm. The higher oil level will help reduce the nose dive under breaking do to less air in the forks(air compresses more than liquid-less air=less compression=less nose dive). Ideally, stiffer springs are in order."
Click to expand...

I read that on another forum as well. Personally I think they are mistaken because the triumph workshop manual has 10w-20 for all Showa kitted bikes. Whereas the Kayaba fitted ones use single weight. It doesn't look like an error.
I've done a lot of reading around now and it seems that there is a very loose standard to define the weight of fork oil. So I've used the centistoke scale (I think that's what it was called) and gone for some silkolene 7.5wt fork oil. I know it sounds daft but it's viscosity is more than some 10w and nearly as much as 15w but it maintains it's viscosity better over a larger range than others. I think that's what showa/triumph must have been trying to achieve with the 10w-20 but am not sure. Anyway it was interesting reading up on it and it's only a few quid if I get it wrong......

Wishbone · Jun 27, 2020

Nope not daft, I use the same chart when choosing my fork oil and it is usually Silkolene RSF Pro too.
What I would do is use your equivalent first and if it seems too light after tests is then remove a measured amount of oil( 25% or 50%) from each fork then add the same amount of maybe 20w equivalent silkolene which should thicken it to 12.5w or 15w depending on how much you removed.
You can also add more of the sameoil to close the air gap but too much is problematic.
Hopefully it works with the first oil. but is tuneable as above.

Wattie · Jun 27, 2020

Wishbone said: ↑

Nope not daft, I use the same chart when choosing my fork oil and it is usually Silkolene RSF Pro too.
What I would do is use your equivalent first and if it seems too light after tests is then remove a measured amount of oil( 25% or 50%) from each fork then add the same amount of maybe 20w equivalent silkolene which should thicken it to 12.5w or 15w depending on how much you removed.
You can also add more of the sameoil to close the air gap but too much is problematic.
Hopefully it works with the first oil. but is tuneable as above.
Click to expand...

Exactly my thoughts. I noted that the silkolene we are talking about is mid range, they have 2.5, 5, 10 and 15w so I figured I've got a lot of leeway to mix them and get a nice response. Thanks for confirming I'm not way off in my thinking.