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
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" have corrected 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.
Spectro is not the only company that has mixed-up oil specifications, so has Castrol, just to mention a major brand, amongst many others.
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.
question mark (?), if any, means I am unsure of that value.
Note: see frontforks.htm article and see front-fork-oil-amounts articles.
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
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, IMO you are 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. Viscosity CAN be depended on, at least when the oil is brand-new, for engine and gear oils, not so for
these fork and suspension oils. Because of that, stick
with ONE manufacturer if you are trying 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 numbers above, 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 this viscosity article. HEED my remarks about sticking
with ONE manufacturer.
|Oil style; Spectro number and description||
|O.SXSF SX400 Platinum Shock & Fork Oil, SAE 2.5W||
|L.SFUL Ultralight shock fluid||10.4||4.4||
|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||
|L.F05 Fork Oil 5W, SSU 105@100°F, 40.6@210°F||21.6||4.4||
L.GSCF125/150, Golden Cartridge Fluid,
The “125” in the model description meant 125 SUS @100°F.
Containers may be marked “5” or Marzzochi
|L.SFVL (prev. called SPL) Golden shock fluid, very light||26.4||9.9||
|L.F010 Fork Oil 10W, SSU 156@100°F, 43.7@210°F||33.3||5.3||
|L.F015 Fork Oil 15W, SUS 220@100°F, 48@210°F||47.2||6.6||
|Old round bottle, #3Light, SSPL series. The bottle says: 220 SUS@100°F; 85 SUS@210°F||47.6||16.9||
|L.F020 Fork Oil 20W, SUS 335@100°F, 54.1@210°||72.2||8.5||
|Belray fork oil 20||
|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
|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 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 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
Just below is a chart, that is the best information I have from BMW. BMW has published such charts in its Owner's Booklets, and elsewhere's, for many years. These charts have changed over the years PRIMARILY due to the better specifications of available oils.
BMW began recommending MULTIGRADE oils decades ago, but BMW restricted their use to usable/safe temperature range back then. As the years passed and oils improved, BMW expanded their recommended 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.
In the mid-nineties, BMW modified the below chart, and no longer recommended the SAE 10W40 or SAE 10W30 to be OK down to -30°C; moving that point back up to -20°C. How many of you ride in that cold of weather?
MOTOR OIL GRADES:
ISO grade @40°C
Cst @100°C (210°F)
32 = 28.8 to 35.2
3.8 to 4.1
46 = 41.4 to 50.6
|4.1 to 5.6|
|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 (210°F)
|80||68 = 460 = 414-506||
7.00 to 11.00
|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 @40°C; 15 Cst @100°C;
calcium 0.27%; zinc 0.135%;
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%;
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 in some
tests, and some tests say 950; Calcium component is 1900 ppm; Phosphorus component is
1000 ppm (some tests say 750. Viscosity is 20 Cst at 100°C. TBM is 8.
Spectro's Golden Spectro 4 oil is a blend of 30% of its Spectro Platinum full synthetic, with
70% of Spectro 4. It is highly treated with copious amounts of ZDDP/ZDTP.
1. Up until recently, BMW sold an engine oil, made for BMW by Spectro. In the 20W50 grade, it
had 1375 ppm of zinc; 1100 ppm of phosphorus; viscosity at 100°C was 18 Cst, and the TBN
2. BMW now sells a Castrol oil under the BMW HP name. This conventional oil in 20W50 tests as
follows: 1207 ppm of zinc; 1014 ppm of phosphorus; viscosity at 100°C was 18.7 Cst, and the
TBN was not available. TAN was 4.12. Viscosity at 40°C was 173.5. Sulfur 14. Calcium 636
ppm. VI was 121.
The following is generally accepted
For MOTOR oils, in STRAIGHT grades, for 20, 30, 40, and 50 grades, the manufacturers do NOT HAVE TO specify at both 100°C (210°F) and 40°C (100°F). A manufacturer may specify at lower temperatures too. 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 needed an additional page!
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. Yes, this seems to conflict with 5W, 10W (and 0W not mentioned). Someday, maybe it will all be clearly stated.
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.
GEAR oil 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.
GL4? GL5? What's the REAL story about these....which are OK for your BMW transmission, driveshaft, rear drive? What's the real information about non-use of GL5 in old BMW transmissions and rear drives? Read the following article. This article is pointed towards cars and trucks and transmissions with brass synchronizers, but has some real solid information. To summarize: GL5 is fine for most any BMW motorcycle, including those before the Airheads.
It has a lot of information you might like to read about your car, etc.
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
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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