What is stock fork oil for GSXR 750 SRAD forks?

[TamSV]

Originally Posted by 21QUEST

Are you sure the Castrol 10w is 15cst @ 40 degrees centigrade?
...edit: Can't see Castrol Mineral 10w on the chart by Peter Verdone .

FWIW, about as sure as I used to be that all 10w oils were the same .

The (mineral) bit was my insertion to distinguish from the fully synth that Castrol also do. The product is just called Castrol Fork Oil 10w. It's on the Verdone list as 15cSt which seems to tie up with this datasheet from Castrol UK here. Castrol Fork Oil 15w is 46.5 cSt which seems a massive jump in spec from the same manufacturer.

However, I also found this - the Castrol Australia datasheet which shows 32cSt for the 10w and 15cSt for the 5w. These numbers seem to make more sense so it could be a typo on the UK datasheet?

Originally Posted by yorkie_chris

Are you sure the stock is suzuki 10 and not the showa 5?

Just going by the Suzuki Service Manual. I don't have any other reference/Haynes etc.


So, in conclusion, bang in the Castrol and see how it feels?

Originally Posted by yorkie_chris

Depends on brand, they are all different viscosities. Maybe Sarah has used some very light 10W around 30cSt which works OK.
Putoline 10w is 46cSt something like that so obviously going to be a bit harsh

wheres that info from? im hoping to swap the oil in mine and am unsure what to use. was ooking at mobil 10w

[yorkie_chris]

http://img380.imageshack.us/img380/5140/oildataup6.jpg
No idea where that originated from, probably putoline themselves. Get in touch yourself if you want to be sure.

But, like I say IMO 10W oils are in general too thick for use in cartridge forks like GSXR or triumph and if it was me I'd be looking at a synthetic 5W like RSF or puto HPX.

[21QUEST]

Originally Posted by TamSV

FWIW, about as sure as I used to be that all 10w oils were the same .

The (mineral) bit was my insertion to distinguish from the fully synth that Castrol also do. The product is just called Castrol Fork Oil 10w. It's on the Verdone list as 15cSt which seems to tie up with this datasheet from Castrol UK here. Castrol Fork Oil 15w is 46.5 cSt which seems a massive jump in spec from the same manufacturer.

However, I also found this - the Castrol Australia datasheet which shows 32cSt for the 10w and 15cSt for the 5w. These numbers seem to make more sense so it could be a typo on the UK datasheet?



Just going by the Suzuki Service Manual. I don't have any other reference/Haynes etc.


So, in conclusion, bang in the Castrol and see how it feels?

Ah yes...

You know, couldn't even find any castrol Fork Oil 10w on the list when I looked(and I thought I looked really carefully lol) but it's there....crazy .

Hmmm must say really surprised at cst value there. I'm not sure really regards any error but yes, does sound quite odd.

Well, you got the bottle so might as well try it lol.

Originally Posted by yorkie_chris

But, like I say IMO 10W oils are in general too thick for use in cartridge forks like GSXR or triumph and if it was me I'd be looking at a synthetic 5W like RSF or puto HPX.

what about for a fat get like me ?

Just ring Maxton, k-tech or kayz and ask them but buy the fork oil of them for the advise, its no dearer.

We have used Silkolene RSF fully synth 10w in those forks for myself (back when had one) and in lots of customers forks for road/track and racing if running stock valving.

Dont get yourself too confused. Air gap and actual setup will have more of an effect on how the bike rides and feels.

Suspension can be simple. Thats the principle we have always worked to and its not done us any harm.

[yorkie_chris]

Just for example of viscosities that RSF10 has 47cSt or thereabouts compared to the castrol 10 at 15cSt!

By the way I should quantify that my experience with 10W in SRAD forks was in cold weather, and they were absolutely horrible. Like you had the comp screws closed completely or no air gap at all or something. That was puto HPX10.

Originally Posted by barwel1992

what about for a fat get like me ?

Same, keep oil the same and use adjusters or valving changes.

If you use thicker oil it changes more with temp, and also if say you needed stronger springs which required a change in rebound valve stack then thicker oil would not cure fact that rebound was weak. Cartridge forks are more advanced than door closers on SV.

found it

http://www.gasgasrider.org/html/susp-oil.htm

im thinking i would be better using something like silkolene pro fst 5wt? instead of mobil 10w?

[TamSV]

Originally Posted by SV650Racer

We have used Silkolene RSF fully synth 10w in those forks for myself (back when had one) and in lots of customers forks for road/track and racing if running stock valving.

Dont get yourself too confused. Air gap and actual setup will have more of an effect on how the bike rides and feels.

Suspension can be simple. Thats the principle we have always worked to and its not done us any harm.

Your final point is hard to argue with.

I wandered into my local bike shop for a chat today and was accused of over-thinking it. I don't like to take their service for granted so came out a tenner lighter brandishing a bottle of 10w Silkolene which was also their recommendation. I was reminded I'm not nearly good enough to notice the difference and better men than me are happy enough with it.

Anyway, not being one to avoid ripping the hole out of a subject - here's the reply I got from Castrol to the e-mail I sent them last night

Dear TamSV,

Thank you for your email.

I am also surprised at that ,as I always assumed that 10W was between an ISO 32 and 46 .....

I can confirm, after looking at the formulation data, that the figures are correct - it is nominal 15 cSt at 40º. 10W grade isn't normally measured at 40º, but at 100º and the V100 still falls into the viscosity range for the 10W specification which is a minimum of 4.0 cSt @ 100º

Interestingly I looked at the Synthetic 10W fork oil, and it was 42 cSt at 40º and 7.5 cSt at 100º - so still falls within the 10W as there is only a minimum viscosity, not a maximum one - but has a considerably thicker low viscosity.

We have never had any complaints from anyone using the 10W fork oil, but I would suggest that depending on the application, if you feel you need a heavier fluid, then go with the synthetic, which will offer better viscosity index and enhanced performance over a mineral oil anyway.

In theory, as long as it is 4.0cSt or more at 100º ... it can be classed as a 10W

What's the application ?

Kind regards
Andy
Automotive Lubricants - UK & Ireland

There then followed a short e-mail exchange where we discover that Andy is also a biker. In the end we agree I'm over-thinking it and probably not good enough to notice the difference.