What is stock fork oil for GSXR 750 SRAD forks?

[TamSV]

Google is not being my friend.:(

I'm changing the seals and oil on the 750 SRAD forks fitted to my SV. The GSXR service manual specifies "Suzuki #10 Fork Oil" which I assumed would be 10W. However, many internetz bods are saying stock is 5W. :confused:

As I weigh the same as the average Japanese rider plus his fat mate, I don't want to go too light.

Any thoughts/knowledge on the subject appreciated. :)

[SV650Racer]

Use 10w with a 100mm air gap.

[TamSV]

That'll do for me :thumright: especially as I had already bought 10w oil.

Many thanks.:D

[yorkie_chris]

Which 10W?

AFAIK stock is 15.6cSt or thereabouts, I like RSF5 which is 26cSt, also AFAIK lightest ones branded 10W start around 30cSt.

I tried 10W putoline in 600 SRAD forks and low speed felt very harsh and stiff even with adjusters all the way out.

[AndyBrad]

Interesting thing about fork oil that chris, that with the same 10w oil rating your getting different charicteristics.

Soo this begs the quetion. Whats the difference and whats good and whats not?

[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

[TamSV]

Which 10W?

AFAIK stock is 15.6cSt or thereabouts, I like RSF5 which is 26cSt, also AFAIK lightest ones branded 10W start around 30cSt.

I tried 10W putoline in 600 SRAD forks and low speed felt very harsh and stiff even with adjusters all the way out.

There I was, all delighted with my 10w oil, and you introduce this. :p

A bit of t'internet research carried out and I now know my SAE's from my ISO VG's. It's a new one on me but makes sense.

I've got Castrol (mineral) 10w oil. According to the Verdone chart posted here on various occasions it is 15cSt. It was a bit of an outlier in his chart for a 10w oil so I tracked down the Castrol datasheet and they agree that it's 15cSt.

So, being a fatty, I should maybe go for something heavier and use the Castrol as flush. Then again, I ride like a granny most of the time so probably wouldn't notice if it was chip fat in there :rolleyes:. Decisions decisions.

[yorkie_chris]

Try it, you should be able to have some working range of adjustment with that.

[21QUEST]

There I was, all delighted with my 10w oil, and you introduce this. :p

A bit of t'internet research carried out and I now know my SAE's from my ISO VG's. It's a new one on me but makes sense.

I've got Castrol (mineral) 10w oil. According to the Verdone chart posted here on various occasions it is 15cSt. It was a bit of an outlier in his chart for a 10w oil so I tracked down the Castrol datasheet and they agree that it's 15cSt.

So, being a fatty, I should maybe go for something heavier and use the Castrol as flush. Then again, I ride like a granny most of the time so probably wouldn't notice if it was chip fat in there :rolleyes:. Decisions decisions.

TamSV,

Are you sure the Castrol 10w is 15cst @ 40 degrees centigrade? I doubt it ;)

Looking at teh chart it'd appear the "Suzuki #10 Fork Oil"(....that's if it's the same as "Suzuki(Forl Oil G10) "... is 33.33cst at 40 degrees.

Used to have a list containing Suzuki Fork oil and their cst values and memory tells me, Suzuki #10 would be in the 30 plus zone.

If you are looking for my recommendation, I'd say Silkolene RSF 7.5(37cst) or any other brand with about the same cst values. This is based on having messed about with different grades of oil to get some forks to feel/work better for me as didn't want to spend money getting them revalved....after spending X amount on a couple of different forks with by the 'Big names'.... and not feeling the work they did weren't worth the money Lol.

Those forks if Standard would work better with oil of about that grade than a light oil would. Certainly not 15 cst.

edit: Can't see Castrol Mineral 10w on the chart by Peter Verdone but more than likely be mid thirties or there abouts(about same as Silkolene RSF7.5) anyway, so yes, should be fine and should provide a good working range of adjustments...as YC says.

[yorkie_chris]

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

[TamSV]

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 (http://datasheets.bp.com/bpglis/FusionPDS.nsf/0/1965AB7DC9413676802577ED00480AAD/$file/BPXE-85KNK8_0.pdf). Castrol Fork Oil 15w is 46.5 cSt which seems a massive jump in spec from the same manufacturer.

However, I also found this (http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/f/Fork_Oil_B1057952.pdf) - 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?

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? :lol:

[AndyBrad]

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]

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 (http://datasheets.bp.com/bpglis/FusionPDS.nsf/0/1965AB7DC9413676802577ED00480AAD/$file/BPXE-85KNK8_0.pdf). Castrol Fork Oil 15w is 46.5 cSt which seems a massive jump in spec from the same manufacturer.

However, I also found this (http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/f/Fork_Oil_B1057952.pdf) - 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? :lol:

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.

[barwel1992]

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 ?

[hardhat_harry]

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

[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.

[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.

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.

[AndyBrad]

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]

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. :roll:

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 :lol:


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. :rolleyes:

:nomore:

[Bibio]

i'm far from being an expert on this subject but here is my 2ps worth.

being a fatty or a skinny has not much to do with it. cartridge forks are a completely different beats to conventional. to thick an oil in cartridge forks will slow the reaction times down which is bad as this will result in loss of traction. the oil ways are a lot smaller than conventional so to heavy an oil will not allow oil to flow freely and let the shims do their job properly. conventional forks have larger oil ways and no adjustment so to fine tune conventional you use thicker oils or a blend till you get the correct viscosity that gives you a good dampening effect. both are dependent on having the correct spring for the rider in the first place. dampening is to control the spring and nothing more, to hard (slow reaction time) and you loose traction to soft (fast reaction time) and the same.

but its late and i like to talk shizzz..

[TamSV]

Makes sense to me Bib. :)

I've pretty much decided that, at a tenner a bottle plus my own free labour, I can afford to do some experimenting.