SLIPPERY SPECS – HOW TO SEE THROUGH THEM
(OR LUBRICANT SPECIFICATIONS AND YOUR BIKE)

Sh! Don’t Mention It! …

All keen motorcyclists have a close relationship with their machine. If it feels good they feel good, and give vice versa. Most riders know that a really important part of this mechanical feel-good factor is OIL. A hard-pushed motor which has the right slippery stuff can sustain a high power output like a well trained athlete on the right diet, with no need for the engineering equivalent of steroids (dubious tuning techniques or wonder additives) which give a short-term boost but long term hassle.

Selecting the right oil for your machine is not easy, and the handbook isn’t always much help. Even well meant advice from pub experts is usually myth-ridden and misleading. The Original Equipment Manufacturers (OEM’s), because they sell bikes in every country on the face of the earth, have to keep it simple, so they just recommend car oils to the run-of-the-mill American “API” specs. This “American Petroleum Institute” defines a number of “S” or “Service” levels for oils which started at SA for Saratoga wagon axle grease and eventually got up to SF and SG in the late eighties. The trouble is all the tests these oils have to pass are run in average car engines turning out about 50 horse per litre, and intended for American freeway conditions. This means thousands of boring, boring miles at a sleep inducing 55mph. Not the sort of thing to get the blood (or oil) racing.

Why not a special “Bike Spec” oil? You may say. Because bike oil isn’t Big Business, so the Faceless Men haven’t even heard of it. So there is not a set of letters or numbers printed on a can which tells you this lube is meant for a compact, high revving 100+ BHP twin-cam engine which has to share its oil with a gearbox. Here in the labs at Silkolene I see oil samples from high performance bikes with engine problems, which are down to the use of basic car oils. These may very well meet the API specs in the handbook, but the “shear-down” in the gearbox has thinned them so much that the cam lobes or bearing have given up. What can you, as your engine’s personal physician, do to ensure its lifeblood isn’t going to cause heart failure?

Listen to reliable dealers, and if you know a race engine builder, go and see what he uses. Engine builders really do know what works and what doesn't’t. And be ready for some home truths about sponsorship. Many a race bike has carried a name on its fairing, which didn't tie up with the stuff in the engine.

To give them due credit, the Japanese OEM’s led by Kawasaki, have tried to break out of the car oil trap over the last year or so. I’ve mentioned API SF and SG, but the Yanks have been working through the alphabet, and now you will see “API SH” in the small print. Even SJ is rolling up in 1997, “SI” being missed out for some strange reason.

Well, Kawasaki followed by Honda and Yamaha have banned API SH. Perhaps a blanket ban is a bit unfair because some SH oils are OK for bikes, but there is a good reason behind it. To add to overweight cars with catalysts that don’t work, the API in their wisdom have thrown in another cosmetic planet-saving idea, energy-efficient oils. These, sadly for the motorcyclist are deliberately shear-prone, very thin, and contain a type of “friction modifier” intended to cut down drag loses at lowish stresses and temperatures. Once again, the Freeway rules. Only the API SH “Fuel Efficient” oils fall into this low-drag class, but the Japanese OEM’s, for the time being, are playing safe, and sticking to API SG oils, 10W/40 or thicker.

A team of five engineers from the Big Three went at the problem very thoroughly, (well, they always do, don’t they?) and gave lightweight Freeway API SH oils a real thumbs-down.

What you poor so-and-so’s can expect is:

a) Hard staring due to slipping of one-way starter clutch.
b) Reduced engine braking due to the back torque limited device slipping.
c) Clutch friction plates slipping.
d) Gear teeth pitting due to low viscosity.

… And that’s official!

I think it’s likely that the Big Three will pull back and OK some of the heavier non-fuel efficient SH oils, but the real message of all this is, forget car oils specs and use lube which is made for bikes, tested in bikes, and raced in bikes.

How Thick Do You Have To Be?

Apart from all the chemical what-not's which keep the engine clean and corrosions free, and make it last for several thousand miles rather than several hundred, the other main purpose of an oil is to be thick ... but not too thick! Take a look at the SAE rating. They are all “something W – stroke – 50” or whatever. SAE 10W/40 is the most commonly recommend viscosity. The “W” stands for Winter, and covers cold start performance. The lower the numbers, the better the chance of a quick start up in sub-zero weather. 20W mean a very marginal start-up at -10°C, but it’s really happier at 0°C and above. 15W means the starter should spin at –10 to –15, and 10W defines a “cold-cranking” test at a non-ferrous monkey endangering -20°C. More than enough protection for any Winter weather we’re likely to see. (I mean for bike engines, not monkeys). There are two more: -5W and Zero W, going down to –25 and -30°C. Never mind endangering reproductive capability, … this is enough to ethnic cleanse the brass subspecies for ever, and nobody rides a bike in those temperatures. (Skidoos are two strokes, and keep their oil thin by mixing it with petrol). I mention this because it has become trendy to sell wide range multi grades such as 5W/50, 0W/40 and even 5W/60. Just because these are technically possible, it doesn’t mean they are a Good Thing. Giving an unnecessary level of cold start performance just to look good in an advert means that a lot of a plastic-like polymer has to be mixed with the oil to make it behave at both ends of the SAE range. (-35 to 100°C for a 0W/40). These polymers always break down or “shear” under mechanical stress, especially between gear teeth. Need I say more? Once again, car engine needs are defining these so-called high tech lubes, and bike engine/transmissions are left out of the equation. Did you know that one of the most advertised synthetic oils with a 5W/50 [now 0W/40] SAE rating is made in an unadvertised 15W/50 version for high performance bikes? Very sensible, but swept under the carpet by the marketing people.

The “hot” end of the SAE range, SAE 20to 60, are all viscosity ratings at 100°C, a typical fat cruising oil temperature for a bike. It’s easy to assume that thick oil protects an engine, but this is not true. Bike engines have small sumps; high capacity oil pumps and loony people in charge who sling the engine around at funny angles. This means the pump intake can have trouble finding the oil, or at least, oil that isn’t full of air bubbles. Thick oil releases air slowly; at least one race team has come to grief at the I. of M. with 10W/60 oil when the oil pump has tried to feed air to the bearings. Bit 60 isn’t all that thick, surely? Yes it is! It’s close up to 140-gear oil, would you believe, so the engine is being asked to do its stuff in a thick goo only found these days in vintage gearboxes. Here are Silkolene we’ve done some interesting work with racing car engines using extra-thin synthetics with really good load-carrying and surface adhesion properties which release several more BHP by reducing drag, and give oil pumps an easy time. This is not a good idea for bikes because the gearbox would suffer, but a really good 10W/40 with the right sort of synthetics can be just as reliable at a 15W/50 in a 750 Super-bike racer, with the added bonuses of a little extra power and good air release. (The Silkolene Suzuki GSXR 750 shows consistent and excellent strip down condition after racing with Comp-4 10W/40 and Pro-4 15W/50.)

Synthetics, or would you trust an ad man with your engine?

I did say, “the right sort of synthetics”; but a synthetic oil is a synthetic oil, isn’t it? No! And again No! There are four totally different types of man … er … person made fluids used as engine lubricants, and each of these is available in all sorts of different grades. The lowest of the low is specially refined mineral oil, which is not really synthetic at all, but the advertising agencies have won the legal right to use their favourite buzz word, regardless of us boring scientists who worry about silly things like truth. Then there are the similar synthetic hydrocarbons, with less load-carrying capability than mineral oil. Great for long oil life in car and truck engines, but a prominent American maker of go-faster camshafts actually advises customers not to use these types of synthetic oil. Mineral oil is actually better than these low performance synthetics in high output engines.

Then there are the BIP synthetics used to reduce smoke from 2-stroke motors, but no 2-stroke road racer or motocrosser uses them; they’re really intended to make the air breathable in Bangkok or Bombay. So, what’s left? Esters! These oil chemicals were first used in aircraft jets, and they still are, but 20 years experience has proven them to be the only really effective synthetic for high output engines, both 4 stroke and 2 stroke. Their great secret is a molecular structure that make them stick to metal surfaces, but they are not “magnetic molecules” as the adverts say! They build up layers on all metals, not just ferrous ones, which protect surfaces from wear when the engine is running, and help during start-up before the oil pressure builds up. These electro statically-held layers really do exist, and they really do work! Unlike the wishful thinking nonsense peddled by International Wonder-Gloop Ltd, Unit 13 Shambledon Factory Estate claiming all sorts of mysterious power releasing effects, top level research has proved the value of esters in reducing wear, friction and catastrophic seizures.
So, if you’re mystified by advertising claims and you don’t believe what it says on the can (a very wise attitude!) ring up the Technical Service department of the Oil Company who make it, and ask. You do not need a PhD to spot an evasive answer.

JOHN ROWLAND
R & D DEPT., SILKOLENE

SYNTHETIC MULTIGRADES

The Basic Facts:

1) SAE 5W, 10W, 15W and 20W ratings are oil thickness (viscosity) measurements at –25°C, -15°C and –10°C respectively.
This is all to do with cold starts in winter conditions.
5W and 10W are really intended to deal with severe North European (or American) winters.

2) SAE 20, 30, 40 and 50 (60 is an obsolete spec, originally for large air-cooled aero engines), all measured at 100°C, a typical sump temperature in a hard-working engine.
SAE 50 gives the best protection in hot climates, where oil temperatures may exceed 100°C.

3) Once an engine has reached its working temperature (if over 70°C) the SAE “W” rating has no effect on the engine

4) Wide-range multi grades (5W/50 etc.) were originally intended for severe climates where cold starts down to -20°C could be expected, followed by prolonged high-speed motorway use. The normal lubricants for moderate climates are 10W/40 (Northern Europe) and 20W or 15W/50 (Southern Europe) Apart from cost, wide range multi grades have a very high polymer content, and can suffer from “shear down” effects, (loss of oil viscosity during use).
It is interesting to note that “MOBIL I RACE”, specially aimed at the motorcycle market, is a 15W/50, so as to handle small, high-revving motors where the MOBIL I is 5W/50 [now 0W/40, 1998]

5) A “synthetic” oil does not automatically guarantee extra engine protection. Those based on synthetic hydrocarbons (PAOs) last longer, but give no better wear protection than a mineral-based oil. Those containing the more expensive synthetic esters also contribute to anti-wear performance; A 10W/50 “pro-4 race”, based on a 100% ester/PAO mixture, is near the end of its development programme, but it will be expensive. It is mainly intended for “super-bikes”.

SAE RATINGS

The Unadorned Facts:

The American Society of Automotive Engineers defines two categories of engine oil viscosity, one which deals with high temperatures typically reached in a modern engine, and one with winter start conditions. SAE numbers 20 to 60 cover five viscosity ranges based on measurements at 100°C. Various types of laboratory kit are used to measure viscosity, but the answer comes out in standard units known as “Centistokes”(cSt).

SAE 20 covers 5.6 to below 9.3 cSt at 100°C
SAE 30 covers 9.3 to below 12.5 cSt
SAE 40 covers 12.5 to below 16.3 cSt
SAE 50 covers 16.3 to below 21.9 cSt
SAE 60 covers 21.9 to below 26.1 cSt

“W” ratings are only relevant to sub-zero cold start conditions.
“W” stands for Winter. (Not “weight” as saloon bar experts will tell you).

A 0W has to be below 3250 cSt viscosity @ -30°C
A 5W has to be below 3500 cSt viscosity @ -25°C
A 10W has to be below 3500 cSt viscosity @ -20°C
A 15W has to be below 3500 cSt viscosity @ -15°C
A 20W has to be below 4500 cSt viscosity @ -10°C

4-STROKE OILS

What Are They?
The oils, which are used to lubricate 4-stroke, motorcycle engines. Classified by viscosity, type and performance these oils are similar in formulation to the motor oils used in car engines, but are NOT the same! Silkolene has developed 4-stroke oils specifically to meet the requirements of motorcycle engines. The highest performance standard currently specified by motorcycle engine manufacturers is API SG. Some API petrol engine specifications nominally higher than SG are in fact car-oriented and not ideal for motorcycle use. All Silkolene motorcycle use. All Silkolene motorcycle 4-stroke oils exceed API SF requirements and most exceed API SG.

Why Do They Need to be Better Than Motor Oils?
Motorcycles with small sumps, high revving, high power outputs and combined engine/transmission lubrication, require lubricants with superior load carrying, high thermal stability and good shear resistance. The “stay-in-grade” or shear resistance of multi grade oil is defined by its Shear Stability Index (SSI). A low figure, around 20 SSI, indicates excellent stability essential for reliable gear operation. Typical car engine oils have a SSI of 30 – 50; Silkolene motorcycle oils generally have SSI values from 15 to 20. Silkolene Pro-4 has an outstanding SSI of 8 and Pro-4 Plus as exceptional SSI of 5.

Mono or Multi grades?
The grade of an oil is determined by its viscosity at a given temperature shown as an SAE number (SAE 15 is lighter and less viscous that SAE 50). Engine manufacturers used to (and sometimes still do) specify lighter oils in winter and heavier ones for summer use, because as an oil increase in temperature its viscosity reduces.

The introduction of multi grades (SAE 15W/50 etc.) enabled the same oil to be used in summer as in winter. In winter at low temperatures a 15W/50 works as an SAE 15W grade during start-up and in the heat of summer works as an SAE 50 grade.

The ability of oil to acts a multi grade generally comes from modified polymer additives in mineral oil formulations although some synthetics naturally exhibit multi grade properties.
In addition to its anti-wear, anti-friction and anti-corrosion properties, what determines the quality of a 4-stroke multi grade is how well it stays in grade. Silkolene has spent considerable time and effort to ensure that every one of its 4-stroke multi grades offer excellent “stay-in-grade” performance. Multi grades generally give better cold start and high temperature operation protection than compromise mono grade oil.

Synthetic or Mineral Lubricants?
Mineral oils are quite adequate for many older engines and new low powered machines but with the introduction of the ‘Super-bike’ a new approach to engine lubrication became necessary. Improvements have been engineered into conventional mineral based 4-stroke oils but despite the best efforts of the formulators, limitations in the basic chemistry mean that they still fall short of the levels of protection needed in the latest highly stressed engines.

Modern engines need modern lubrications and that means Synthetic Lubrication Technology. Silkolene has pioneered the development of synthetic lubrication technology for the aerospace and aviation industries. This technology has been utilised as the basis for the exclusive Silkolene range synthetic fortified 4 stroke oils for motorcycles.

Not All Synthetics Are Created Equal
The synthetics used in engines oils fall into two categories …
Synthetic Hydrocarbons (PAOs) - these are synthesised mineral oil and Synthetic Esters, which are used extensively in aerospace applications. Silkolene uses this Ester “Aerospace Technology” for optimum performance in its range of 4-stroke motorcycle engine oils.

Lubrication When and Where it’s Needed
Up to 50% of engine wear takes place during start up, when parts are not fully lubricated. Every time you switch the engine off, the oil gravitates back to the sump and within a matter of hours, engine parts are left with inadequate protection. During the first vital few seconds when the engine is restarted, before full lubricant flow is achieved, such components as rings, irreversible wear damage. In addition, the anti-wear additives in conventional engine oils don’t become fully effective until the oil film between stressed components reaches 50-60°C. In many short trips, the oil doesn’t warm up sufficiently to activate these anti-wear additives, in some areas such as overhead cam gear. Silkolene’s ester synthetics form a long lasting film on all wear parts which protects them from the moment the engine is fired up, giving excellent lubrication when and where its needed the most.

A Carpet of Protection
Silkolene’s synthetic esters actually bond to engine surfaces and provides a tough film of lasting protection which stays in place long after the engine is shut off and the lubricant has stopped pumping. It dramatically reduces wear on start up and offers outstanding wear protection right through the engine’s operating temperature range.

PAO/ Ester/ Mineral Oil Performance Comparison

	Esters	PAOs	Selected Mineral Oil
Long Oil Life	V Good	V Good	Average
Long Temp Protection	Excellent	Good	Good
Long Temp Performance	Excellent	Excellent	Good
High Temp Performance	Good	Poor	Average
(without Chemical Enhancement)
High Temp Performance	Excellent	V Good	Good
(with Chemical Enhancement)
Lubricating/ Anti-friction Performance	Excellent	Poor	Average

ENGINE OIL CLASSIFICATION SYSTEM FOR AUTOMATIVE GASOLINE ENGINE SERVICES
“S” – SERVICE OILS

API Automotive Gasoline Engine Service Categories	Previous API Engine Service Categories	Related Industry Definition	Engine Test Requirements
SA	ML	Straight Mineral Oil	None
SB	MM	Inhibited Oil Only	CRC L-4* or L-38; Sequence IV*
SC	MS (1964)	1964 MS Warranty Approved	CRC L-38; Sequence IIA*;
			S. IIIA*; S. IV*; S. V*; Caterpillar L-1*
			(1.0% Sulfur Fuel)
SD	MS (1968)	1968 MS Warranty Approved	CRC L-38; Sequence IIB*;
			S. IIIB*; S. IV*; S. VB*; Falcon Rust*; Caterpillar L-1* or 1H*
SE	None	1972 MS Warranty Approved	CRC L-38; Sequence IIB* or IIC or IID; S. IIIC* or IIID; S. VC* or V-D
SF	None	1980 MS Warranty Approved	CRC L-38; Sequence IID;
			S. IIID; S. V-D
SG	None	1989 MS Warranty Approved	CRC L-38; Sequence IID;
			S. IIIE; S. VE; Caterpillar 1H2
8This test is obsolete; engine part, and/or test fuel, and/or reference oils are no longer generally available and the test is no longer monitored by the developer or ASTM.

API Automotive Gasoline Engine Service Categories Previous API Engine Service Categories Related Industry Definition Engine Test Requirements

SA – Formerly for Utility Gasoline and Diesel Engine Service (Obsolete)
The category SA denotes service typical of older engines operated under such mild conditions that the protection afforded by compounded oils is not required. This category has no performance requirements, and oils in this category should not be used in any engine unless specifically recommended by the equipment manufacturers.

SB – Minimum Duty Gasoline Engine Service (Obsolete)
The category SB denotes service typical of older engines operated under such mild conditions that only minimum protection afforded by compounding is desired. Oils designed for this service have been used since the 1930's and provide mild anti scuff capability and resistance to oil oxidation and bearing corrosion. They should not be used in any engine unless specifically recommended by the equipment manufacturer.

SC – 1964 Gasoline Engine Warranty Maintenance Service (Obsolete)
The category SC denotes service typical of gasoline engines in 1964 through 1967 models of passenger cars and some trucks operating under engine manufacturers’ warranties in effect during those model years. Oils designed for this service provide control of high- and low-temperature deposits, wear, rust, and corrosion in gasoline engines.

SD – Gasoline Engine Warranty Maintenance Service (Obsolete)
The category SD denotes service typical of gasoline engines in 1968 through 1970 models of passenger cars and some trucks operating under engine manufacturers’ warranties in effect during those models as specified (or recommended) in the owners manuals. Oils designed for this service provide more protection against high- and low-temperature engine deposits, wear, rust, and corrosion in gasoline engines than oils that are satisfactory for API Engine Service Category SC and may be used when API Engine Service Category SC is recommended.

SE – 1972 Gasoline Engine Warranty Maintenance Service (Obsolete starting in
1989)
The category SE denotes service typical of gasoline engine in passenger cars and some trucks beginning with 1972 and certain 1971 through 1979 models operating under engine manufacturers’ warranties. Oils designed for this service provide more protection against oil oxidation, high-temperature engine deposits, rust, and corrosion in gasoline engines than oils that are satisfactory for API Engine Service Categories SD or SC and may be used when either of these categories is recommended.

SF – 1980 Gasoline Engine Warranty Maintenance Service
The category SF denotes service typical of gasoline engine in passenger cars and some trucks beginning with 1980 through 1988 model years operating under engine manufacturers’ recommended maintenance procedures. Oils developed for this service provide increased oxidation stability and improved anti-wear performance relative to oils that meet the minimum requirements for API Service Category SE. These oils also improved protection against engine deposits, rust, and corrosion. Oils meeting API Service Categories SE, SD or SC are recommended.

SG - 1989 Gasoline Engine Warranty Maintenance Service
The category SG denotes service typical of gasoline engines in present passenger cars, vans, and light trucks operating under manufacturers’ recommended maintenance procedures. Category SG quality oils include the performance properties of API Service Category CC (Certain manufacturers of gasoline engines require oils also meeting the higher diesel engine Category CD). Oils developed for this service provide improved control of engine deposits, oil oxidation, and engine wear relative to oils developed for previous categories. These oils also provide protection against rust and corrosion. Oils meeting API Service Category SG may be used where API Service Categories SF, SE, SF/CC or SE/CC are recommended