If you are interested in how oil REALLY lubricates, refer to:
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 & Cst,
& 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; this L will be found on the containers in 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 and read these 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 depended upon.
In the early Airhead days, BMW fork oil was red & 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, & the lack of superior stiction fighters, & some other characteristics,
IMO you are better off with a REAL fork oil....especially a full synthetic fork oil. For the various
fork oils & 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 & 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, ~ 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 SSU 90 ?||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”||16.9||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, light. 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 testing on Castrol 10 wt fork oil. Castrol has published its
|Silkolene Pro RSF 2.5Wt||14.||5.8|
|Military Mil-H-5606E, the original red BMW oil (~4wt)||MIN 13.2||MIN 4.9|
|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 data, & the chart, that Spectro-oils.com
had on their website. I notified Spectro Oils on these occasions, & 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; & this chart, clickable below in pdf format, has been corrected by
Spectro themselves at my urging.
This link to a color bar chart can be useful, is easy to read.....AND....it lists more oils than I
have on this page you are now reading; I have imported it, in pdf format, into this website.
You may find that chart very useful:
Here is a link to someone else's compilation of fork oil weights:
Factory recommendations for engine oils:
Below is a chart, that is the best information I have from BMW. BMW has published various
such charts in its Owner's Booklets & 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 ranges. As the years passed & oils improved, BMW expanded their their
recommended temperature range, but generally only for the high end temperature rating of any
given multigrade oil.
In the chart below, BMW listed its Super Power oil. I do not recommend it; unless you plan on starting
your bike in extremely cold weather, consistently below freezing. I recommend 15W50 or 20W50 for
most riders. Those riders riding consistently at high speeds, or pulling trailers or sidecars, should
probably use a 20W50. I also do NOT recommend single weight oils. It is my belief that they are only
included on BMW's chart because only single weight oils are easily available in some countries.
In the mid-nineties, BMW modified their recommended oil viscosity range charts.
The below chart is the very last version for AIRHEADS. It incorporates a number of changes.
BMW also sold its SuperPower oil, 5W50, for extreme conditions, -30°C to +40°C. I do NOT
recommend that oil unless you are in such extremely cold weather. BMW showed that oil on
older charts,but changed its placement on the temperature graph, and then, finally, moved it to
a simple tiny text on the same page as the chart, but not IN the chart. I would NOT use
that oil over that wide temperature range.
NOTE especially that 10W50 is not recommended for over +10°C; and the 15W50 is not
recommended for over 30°C. Contrast with the 20W50. There is a real reason that
certain multigrade oils are not good at higher temperatures, even though they have that top
figure in their stated viscosity. I can sum it all up rather easily: When the top number is
divided by the bottom number, and it exceeds 2.5, the oil fails to lubricate well-enough.
This has BEEN SO, for DECADES, and IS SO, today. It also applies to the BMW 5W50
SuperPower oil...please do NOT purchase that oil, no matter what BMW says!...unless
the air temperature will be below freezing, during your entire ride.
One final comment. The temperatures in the chart are for the RANGE of air temperatures
you will be riding at. That has some broader implications than you may think. NOTE,
especially, that the chart is VERY CLEAR about the grade of oil most every rider will or
should be using: 20W50 or 15W50. Many riders use 10W40 in mild Winter conditions, but
might be better for them to use 15W50.
Article on this website dealing with cold weather starting, etc.:
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+|
|Only for severe conditions should you even think about using over 90 weight oil. I am OK with synthetic oils in the transmission, but prefer dino oils, GL5, NOT GL4, in the rear drive. MORE info further down this article, below....in NERDY NOTES section....|
Miscl. oil information:
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 & phosphorus. AFAIK, Spectro
uses both ZDDP and ZDTP, depending on synthetic, or not, or part synthetic.
Golden Spectro 4 is 30% Spectro Platinum full synthetic, and 70% Spectro 4.
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.
1. Some time ago 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 was 7.5. This oil was made for Classic K
bikes, and sold for them AND Airheads. Earliest of the Classic K bikes
required zinc and phosphorous to SG type level amounts.
2. BMW sold a Castrol oil under the BMW HP name. This conventional oil in
20W50 tested 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.
3. I don't have the specifications on any other BMW oils.
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 at both 100°C (210°F) and 40°C (100°F). A manufacturer may
additionally specify at even 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
needed an additional page! It is best to avoid single grade oils. If the country you are
traveling in has nothing but single grades, then use them. No oil is worse! :-)
SAE motor oil 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. But I
am sure you can deduce WHY this was done, originally.
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 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 many of those before the Airheads.
It has a lot of information you might like to read about your car, etc.
Note that there is one bronze spacer (shim) in the rear drives.
BMW SPECIFIES GL5 oil. BMW knows what is OK,
>>>>and BMW does NOT say GL4!
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.
01/02/2016: Update meta codes; narrow article; left justify abp, clean up some.
Add latest BMW factory information (a few small changes on engine oils)
02/05/2016: Add link to coldstarting.htm article
© Copyright, 2014, R. Fleischer
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