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Oil viscosities, viscosity indexes, suspension fluids, shock absorber fluids, SAE, SUS, Cst
for BMW and other motorcycles (and even some bicycles!)
 Covering motor oils, gear oils, transmission oils, rear drive oils, fork and suspension oils


 viscosity.htm
 51-D
© Copyright, 2012, R. Fleischer

If you are trying to modify shocks or suspension by changing the type of oil viscosity, or if you are curious about motor and gear oils, etc., this article may be of help.
If you are interested in how oil REALLY lubricates, etc., refer to my other articles.



Some years ago, most of the oil packaging industry changed from using SUS (Saybolt Universal Seconds) to Centistokes, in describing viscosity.   I found ERRORS in Spectro Oils own charts and graphs on their website; SOME of which was THEM confusing SUS and Cst.  In February of 2010 I notified Spectro of these errors, and they "should" be correcting them.  The information I present to you below is the CORRECT information, as far as I know, no matter what you may find in literature from Spectro Oils.

 Here is a website that has a chart, pdf format, that includes many oils I do not have listed below, AND EVEN SOME BICYCLE SHOCKS OILS!
http://www.peterverdonedesigns.com/files/suspension oils.pdf

I do have information available on the viscosity and VI for SOME oils from SOME other manufacturers such as  Belray, Harley, Honda and Yamaha shock/suspension oils.  There is a lot of it in the SPECTRO pdf chart, that is BELOW as a hyperlink.

For Spectro products, the L. in front of the several characters following, means LITER size containers, and this L will be found on the containers as the product number.  Other container sizes will have different prefixes, such as the small container that has an O as prefix for the SX400 oil, below, which signifies a PINT (why not a P?, no, I don't know) container.  I list these prefixes, below, so that if you see them on your container, you will not be confused.    It is the SAME oil inside the container, no matter what prefix is in the part number.

A question mark (?), if any, means I am unsure of that value. 
 

 

Oil style; Spectro number and description Cst@40°C (100°F) Cst@100°C (210°F)  Viscosity Index
O.SXSF  SX400 Platinum Shock & Fork Oil, SAE 2.5W              5.0              1.9                 400
L.SFUL Ultralight shock fluid            10.4              4.4                385
L.GSCF85/150, Golden Cartridge Fluid, very light.
 The “85” in the model description meant 85 SUS @100°F (16.9 Cst).  Later containers may be marked as “7.5”		            16.2              3.5                   150          
L.F05  Fork Oil 5W, SSU 105@100°F, 40.6@210°F            21.6              4.4                102
L.GSCF125/150, Golden Cartridge Fluid, light.
The “125” in the model description meant 125 SUS @100°F.
Containers may be marked “5” or Marzzochi
 		            26.0              4.5                150
L.SFVL (prev. called SPL) Golden shock fluid, very light            26.4              9.9                400
L.F010 Fork Oil 10W, SSU 156@100°F, 43.7@210°F            33.3              5.3                101
L.F015 Fork Oil 15W, SUS 220@100°F, 48@210°F            47.2              6.6                100
Old round bottle, #3Light, SSPL series.
The bottle says:  220 SUS@100°F; 85 SUS@210°F		            47.6            16.9                325
L.F020 Fork Oil 20W, SUS 335@100°F, 54.1@210°            72.2              8.5                 100
       
       
NON-Spectro Oils:      
Belray fork oil 20             82              9.5                100
Harley Davidson Screaming Eagle             67.3             10.42  
Harley Davidson Type E             38              7  
Belray fork oil 10             37.4              5.8                100
Honda Showa SS8 Fork Oil  10W             35.48                     7.38                 200
Belray H.V.I. 5W shock fluid             20.75              6.67                300
Belray fork oil 5W             20.5              6.2                280
Honda Showa SS7 5W fork and shock oil             16.49              3.77                130
Yamaha 01 fork oil for Kayaba             14.57              3.45                150
Belray H.V.I. 3W shock fluid             12.6              4.1                300
Belray fork oil 2.5W              9.2              1.9                   60
Maxima bicycle fork fluid 10Wt, or fork oil 10Wt             32.              6.28  
Motul fork oil, light             20.              6.  
Rockshox 5W medium, hydracoil, Torco             19.9              5.7  
Castrol fork oil 10Wt             15.              4.  
Silkolene Pro RSF 2.5Wt             14.              5.8  
Military Mil-H-5606E, the original red BMW oil (~4wt)   MIN  13.2   MIN   4.9  
ASK, I have plenty more.  E-mail me:  CLICK      
Motor oil and gear oil grades are in another chart, BELOW      

COMPARO BAR-CHART, PDF Format:

In early 2010, I noticed, on two occasions, errors in the data, and the chart, that Spectro-oils.com had on that website.   I notified Spectro Oils on both these occasions, and the last error, a serious one of reversing the 40°C/100°C data on a comparisons of oils chart was fixed by Spectro; upon which they sent me another thank you note.   The above data on this page is corrected, and comes from updated information; and the chart, clickable below in pdf format, has been corrected by Spectro themselves at my urging.

This chart can be useful, as it lists more oils than I have on this page you are reading; and gives a colored bar-chart appearance, which may be easier for you to use.

I have imported it, in pdf format, into this website.

Here is a hyperlink to it:   ShockOilComparo.pdf
 

MOTOR OIL GRADES:

SAE Motor (ENGINE) grade

 ISO grade @40°C

           Cst @100°C (assume same as 210°F)
                                          0                               -3.8
                                          5

     32 = 28.8 to 35.2   

                        3.8 to 4.1
                                         10                                46 =  41.4 to 50.6                         4.1 to 5.6
                                         15                                              
                                         20                                68 = 61.2 to 74.8                         5.6 to 9.29
                                         30                               100 = 90.0-110                            9.3 to 12.49
                                         40                               150  = 135 - 165                       12.5 to 16.29
                                         50                               220 = 198-242                       16.3 to 21.89
                                         60                               320  = 288-352                       21.9 to 26.09
     
     

GEAR OIL GRADES:

SAE GEAR Grade 

                           ISO grade @40°C

           Cst @100°C (assume same as 210°F
                                         70                                 4.1+
                                         75                                 4.1+
                                         80                         68 = 460 = 414-506                             7.00 to 11.00
                                         85                               ~100                              11+
                                         90                       220 =680 = 612-748                             13.5 to 23.99
                                       140                     ~500 = 1000 = 900-1100                             24 to 40.99
                                       250                    1500 = 1350-1650                              41+
     
     

 

Miscl. oil information (here, since I had inquiries!):

Shell Rotella-T oil in 15W40:  100 Cst @40°C; 15 Cst @100°C; calcium 0.27%; zinc 0.135%; phosphorus 0.120%.

Valvoline 4-stroke motorcycle oil, 10W40:  104.1 Cst @40°C; 15.2 Cst @100°C.
       "           "               "            "   20W50:  169.4                      18.6
       Both of the above Valvoline oils: zinc 0.112%; phosphorus 0.104%; calcium 0.182%; sodium 0.052%

Spectro engine oils:  All have 1800 ppm zinc and phosphorus
Castrol's 4T oil, (and Grand Prix oil, which is the SAME OIL) in either grade 10W40 or 20W50, as appropriate to your climate, is SG rated and formulated.  Zinc component is 1100ppm; Calcium component is 1900 ppm; and Phosphorus component is 1000 ppm. 

 


NOTES!!

Here is another source for viscosity information, presented somewhat differently, and with some other brands listed with specifications:
         http://www.peterverdonedesigns.com/lowspeed.htm
 


The following is generally accepted standard information:

For MOTOR oils, in STRAIGHT grades, for 20, 30, 40, and 50 grades, the manufacturers do NOT HAVE TO SPECIFY viscosity at 0°F;…only needed are at 210°F.  
In general, most oils are USUALLY specified at 100°C (210°F) and 40°C (100°F).  A manufacturer may specify at lower temperatures.  The actual SAE official methods of specifying viscosity are rather complex, particularly for motor oils at temperature extremes, so I have not gotten into this in depth in this article, which would have add a whole page to it!

SAE grades 5W and 10W have a LOW temperature specification.
SAE 5W need not have any minimum at 0°F but a maximum generally taken to be 6,000 SUS; 10W has a maximum at 0°F, generally taken to be 12,000 SUS, and a minimum generally taken to be 6,000.   In older specifications, some of which may still be in use, oils under 20 weight are generally taken to NOT have any 210°F rating for viscosity, except a minimum.  The specifications on oils were set up so that oils that had a W in their specification were not specified at 0°F, but at 210°F.

 Figures are based on a VI of 96 in single grades. Because of this, and the fact that oil viscosity indexes can vary so widely, take all these figures, that seem so precise, as approximates.

For GEAR grades: 
SAE grades 75W, 80W, and 85 W have a LOW temperature specification.
I have not listed the NON-'W" gear grades.   These have similar 100°C ratings.
You have probably noticed that GEAR oils have their own viscosities, and generally a gear grade number is close to twice an engine oil grade number, for roughly the same viscosity.    There ARE straight single weight gear oils.  An example might be a straight 90 weight gear oil.  This can have a specification at 210°F of 75 to 120 in viscosity, SUS.
 

Yes, it is confusing!

Converting SUS to Cst:

NOTE!  The conversion formula varies, depending on the rated SUS value.
Other, less accurate formulas exist, and are usually plenty good enough.

SUS between 32 and 99; use this formula:
Cst = 0.2253 x SUS - (194.4 ÷ SUS)

SUS between 100 and 240; use this formula:
Cst = 0.2193 x SUS – (134.6 ÷ SUS)

SUS greater than 240; use this formula:
Cst = SUS ÷ 4.635

 

Revisions:
03/12/2010:    O.SXSF had two entries, with different viscosities, due to Spectro Website confusion. Obtained
                         correct information.   ALSO re: L.SFVL, 400 VI was confirmed, so its question mark was eliminated.
03/18/2010:    Make first chart a formal TABLE, to keep things in nice order
03/22/2010:    Greatly expand information, clean up page......and convert to tables format throughout so display in
                          various  browsers and screen sizes is consistent (I hope!)
03/23/2010:   Add hyperlink: http://www.peterverdonedesigns.com/files/suspension%20oils.pdf
                         later that same day, add more listings.
04/05/2010:   Update; and ADD  ShockOilComparo bar chart in pdf format as hyperlink
04/13/2010:   Add more oils and specifications
 11/18/2010:  add Castrol 4T
02/24/2011:  change from 52F to 52D.
02/24/2011:  was 52D, now 51D.

© Copyright, 2012, R. Fleischer

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