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.

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.

Use 10w with a 100mm air gap.

[TamSV]

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

Many thanks.

[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.

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]

Originally Posted by 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.

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

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 . Decisions decisions.

[yorkie_chris]

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

[21QUEST]

Originally Posted by TamSV

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

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 . 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?