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Oil viscosities, viscosity indexes, suspension fluids, shock absorber fluids, motor oils, gear oils,
transmission oils,  rear drive oils, fork and suspension oils.  BMW Factory recommendations chart.
SAE, SUS, Cst.
Some info on ZDDP content.
For: BMW and other motorcycles (and even some bicycles!)

viscosity.htm
51-D
Copyright, 2014, R. Fleischer

If you are trying to modify shocks or suspension by changing the 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, refer to oilessay.htm


SPECIAL NOTE:

Some years ago, most of the oil packaging industry changed from using SUS (Saybolt Universal Seconds) to Centistokes when describing viscosity.   I found ERRORS in Spectro Oils own charts/graphs on their website.   THEY were confusing SUS and Cst, and a few other things.  In February of 2010 I notified Spectro of these errors, and they "should" be correcting them.  More on this much later in this article.
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.
 


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. 
 

Note:  see frontforks.htm article and see front-fork-oil-amounts articles.
 

Fork oils:

I prefer Spectro's fork oils, or suspension fluids.  They are GOOD, have low stiction, wide temperature range (decent VI too), and the viscosities can be depended upon.  

In the early Airhead days, BMW fork oil was red, and was really a military hydraulic oil.   You could find its full specifications using a search
engine for:  MIL-H-5606E.  Just to save you the trouble, the viscosity specifications for that oil are:
MINimum 4.9 Cst at 100 C
MINimum 13.2 Cst at 40 C
Maximum 600 Cst at -40 C

Due to how it is specified, and the lack of superior stiction fighters, and some other characteristics, you are MUCH better off with a REAL fork oil....especially a full synthetic fork oil.    For the various fork oils and suspension fluids, the various manufacturer's do not agree on measuring viscosity.  That is nearly cut and dried for engine and gear oils, not so for these oils.  Because of that, stick with ONE manufacturer if playing with different or testing different viscosity grades.   Except for some GS models, all the old BMW's needed a very thin oil, roughly SAE 4.    For the most part, you can translate that to modern 5 to 7-1/2 fork oils.     Note the 4.9 and 13.2 at the temperatures cited; compare those figures with YOUR manufacturer's figures.   A formula to convert Cst to SUS is in the viscosity article, link just below.  But, HEED my remarks about sticking with ONE manufacturer.


 

Oil style; Spectro number and description

Cst@40C (100F)

Cst@100C (210F)

 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 @100F (16.9 Cst).  Later containers may be marked as 7.5            16.2              3.5

                     150   

L.F05  Fork Oil 5W, SSU 105@100F, 40.6@210F            21.6              4.4

               102

L.GSCF125/150, Golden Cartridge Fluid, light. The 125 in the model description meant 125 SUS @100F.
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@100F, 43.7@210F            33.3              5.3

               101

L.F015 Fork Oil 15W, SUS 220@100F, 48@210F            47.2              6.6

               100

Old round bottle, #3Light, SSPL series.  The bottle says:  220 SUS@100F; 85 SUS@210F            47.6            16.9

                  325

L.F020 Fork Oil 20W, SUS 335@100F, 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. To the left is ACTUAL testing on Castrol 10 wt fork oil.  Castrol has published its own specs.  Castol used mm squared divided by sec. for its 'measurements'.  They published the information as:
synthetic oil:  5.7 at 100F & 28 at 40C, & VI of 151.  For 10wt oil listed in the left columns, they say 42, 7.5, & VI 150.  For just "Fork Oil" they say 15, 4.0, & 150. MY advice: disregard Castrol.
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 their website. I notified Spectro Oils on these occasions, and the last error, a serious one of reversing the 40C/100C 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 comes from updated information; and this 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.
You may find that chart very useful:   ShockOilComparo.pdf

 


Factory recommendations:
Just below is a chart, that is the latest information from BMW.  BMW has published similar or somewhat similar charts in its Owner's Booklets, and elsewhere's, for many years, and these charts have changed over the years due PRIMARILY in the increase in the quality of the oils that are available. 

BMW began recommending MULTIGRADE oils long ago, but they were restricted in usable/safe temperature range by BMW back then.  As the years passed, and the oils improved, BMW expanded the temperature range, but only for the high end temperature of any given multigrade oil.
In the chart below, BMW listed its Super Power oil.  I do not recommend it.  I recommend the 15W50 or 20W50 for most riders.  Those riders riding consistently at high speeds, or pulling trailers or sidecars, should probably use a 20W50.
Note also, that in the mid-nineties, BMW modified the below chart a bit, and no longer recommends the SAE 10W40 or SAE 10W30 to be OK down to -30C, BMW moved that point back up to -20C.  How many of you ride in that cold of weather?





 


 

MOTOR OIL GRADES:

SAE Motor (ENGINE) grade
 

 ISO grade @40C

Cst @100C (210F)

                       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 @40C

  Cst @100C  (210F)

                       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:

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

Valvoline 4-stroke motorcycle oil, 10W40:  104.1 Cst @40C; 15.2 Cst @100C.
       "           "               "            "  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

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 0F;only needed are specifications at 210F.   In general, most oils are USUALLY specified at 100C (210F) and 40C (100F).  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 0F but a maximum generally taken to be 6,000 SUS; 10W has a maximum at 0F, 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 210F 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 0F, but at 210F.  Yes, this seems to conflict with 5W, 10W (and 0W not mentioned).

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 figures that seem 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 100C 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 210F 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 many screen sizes is consistent.
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.
08/08/2012:   Add two links (to my articles)
08/09/2012:   revise layout
10/15/2012:   Add QR code, add language button, update Google Ad-Sense code
11/07/2012:   Greatly improved table presentation; but NO technical details changed.
01/21/2014:   Remove Peter Verdone Designs hyperlink, website is NLA
03/03/2014:   Add more information on fork oils before the chart.
08/04/2014:   Add factory recommendations chart and information, for engine oils.

Copyright, 2014, R. Fleischer

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