Fork oil

[pete-blen]

I'm changing the fork oil in a CRF150f...
i want to put a 20w oil back in , to give more
damping/slow the return..
I know a 20w from one company
could be the same as a 15w from another..
So who makes a "true" 20w oil ??
i know this is prob a can of worms question..

[husaberg]

I'm changing the fork oil in a CRF150f...
i want to put a 20w oil back in , to give more
damping/slow the return..
I know a 20w from one company
could be the same as a 15w from another..
So who makes a "true" 20w oil ??
i know this is prob a can of worms question..

someone posted the results of a cross reference I think it was on a Robert Taylor thread
I will find it.
http://www.kiwibiker.co.nz/forums/newreply.php?do=newreply&p=1130716550
There is a special word t describe the matching of the viscosity buggered if I know it..........
(later) centistokes


With the greatest respect a lot of you guys just assume so much and the reason for this thread is no different. A purchaser assumed that what the seller was claiming had 100% integrity. if you dredge through any number of other motorcycle related forums you will very quickly reason that the misgivings about the said product are significant.

When we are talking about ''oil weight'' the SAE ratings that suspension oils are rated at to be sold over the counter is ( to not put too fine a point on it ) ''a crock of s..t'' Rating a suspension oil by using a motor oil rating is complete and utter nonsense.
The only way to compare apples for apples is by using the centistoke scale, that far more accurately represents flow rate, one of the major preoccupations when determining what fork oil etc that you require.
Aside from the fact you shouldnt mix oil brands without starting with completely dry components ( and thats another story ) DIFFERENT BRANDS OF OIL SHOWING THE SAME SAE RATING ON THE BOTTLE WILL OFTEN HAVE SIGNIFICANTLY DIFFERENT CENTISTOKE FLOW RATINGS. Which in this one case will affect rebound response.

EG

Belray fork oil ( sae ) 2.5 wt 9.2 centistokes at 40 degrees celsius

Silkolene Pro RSF ( sae ) 2.5 wt 14.0 centistokes at 40 degrees celsius ( in my opinion an excellent oil )

Maxima 5wt fork oil ( sae ) 5 wt 16.9 centistokes at 40 degrees celsius ( in my opinion also an excellent oil )

Get the picture? You could have had Maxima 5wt and then in all innocence purchased a bottle of Silkolene 2.5 and noticed for all practical intent no useful difference. Certainly not what you were looking for

To the best of my knowledge ( but I am prepared to be corrected ) Ohlins are the only company that have the foresight and decency to have the centistoke rating included in the labelling on the bottle. With all other manufacturers that I know of you have to access their spec cards off their websites, if all suspension oil manufacturers make this information available on their websites I dont know.


To mildly correct you RT, suspension fluid should in fact be referred to in centipoise (cP), being the measurement of the oils dynamic (or absolute) viscosity - the oils resistance to flow, whereas centistokes (cSt) is the measurement of the oils kinematic viscosity - the ratio of the dynamic viscosity to the density of the fluid. However, either way works for your purpose as they are effectively equal, that is 1 centipoise equals 1 centistoke.

Handy chart attached that shows many common suspension fluids sae rating and cSt rating attached which backs up your post above (you'll need to click on the window that opens again to get it to open in it's own browser page so that it can be enlarged enough to read!).
It amazes me that more manufacturers haven't gone down the centipoise/centistoke path with suspension fluid given that there is a much greater awareness of suspension upgrades etc., these days.

just to let you know if you are using 20 weight and the damping is incorrect or Crude (that's an oil joke btw) the fix is not oil (but you know that already)
As its a play bike(I guess) the oil is the cheapest fix, Emulators to sperarate the comp and rebound damping chores is a far better Band-Aid.

[Rhys]

20w would make the shocks quite firm

[pete-blen]

just to let you know if you are using 20 weight and the damping is incorrect or Crude (that's an oil joke btw) the fix is not oil (but you know that already)
As its a play bike(I guess) the oil is the cheapest fix, Emulators to sperarate the comp and rebound damping chores is a far better Band-Aid.[/QUOTE]


thanks for the linky thing... Knew that thread was here..Just couldn't find it...
Yes a play bike of sorts...
Just picked it up for my 13yo... not had a lot of maintance "if any'
already had to replace all wheel bearings./ free the caliper up..etc..
a 03 CRF150 for $1200 wasn't going to be with out issues..
Swing arm & linkage bearings/seals next.. needs a new disc rotor..
He's learning how a motor bike is put togeather..so all good..

[F5 Dave]

10w would be far more suitable. 20w in a dirt bike should be foul.

[Flip]

10w would be far more suitable. 20w in a dirt bike should be foul.

++1


He should know.

[pete-blen]

10w would be far more suitable. 20w in a dirt bike should be foul.

you are prob right:niceone:... it had NO damping what so ever...
After draining them I got 1 drip out of one leg & 3 out of the other..
no where near the 290cc per leg...
But I had already bought the 20W Maxima oil... so it's got that
in it now...