Use what ever oil you want. If you follow the
manufacturer's recommendations, or not is up to you. Big boy rules are in
effect.
However, do yourself a favor and become
INFORMED.
Basics:
Oil weight (viscosity) - The 40 in a "5w-40" weight
oil is the main operating weight of a given oil and determines how well the oil
will flow between bearings and tight clearances under operating conditions
measured at 212 degrees F (100 C). In all reality this has nothing to do with the protection
available from a given oil, only the film viscosity - particularly the film that
the bearings and cam run on when spinning, and the film between the pistons,
rings, and bores. A lighter weight oil can reduce
the power required to drive the oil pump and other parts slightly, while
decreasing windage in the engine, but this usually comes at the cost of reduced life compared to a
heavier weight oil of the same brand and type. An oil that may start out as a
5w-40 may eventually break down to a 30 weight oil in several thousand
miles.
Multi-viscosity - How well the oil flows cold and
hot. In multi-grade oils, the first number (5w in 5w-40) is
measured at 32 degrees F (0 C) - "w-" stands for winter, and relates to how well the oil flows
through the engine at start up until the engine becomes warm, as well as how
well it drains back off parts and into the oil pan when cold. If the oil easily runs back into the sump, it also drains from parts easily. This means that less of it is on the bore walls, piston, cams, gears, etc. when you start it up next.
The difference
between a 5w- and a 10w- is not as large as many would have you believe, and for
those who never start their car below 30 degrees F due to local weather or the car
being stored in a garage, it is irrelevant other than how quickly the viscosity
modifiers may break down in an oil with a wider viscosity range. The trend
towards lighter and lighter multi-grade oils by manufacturers is generally an
issue of mileage and emissions.
Viscosity modifiers are generally
coiled, branch chain molecules that look like a
spring that unwinds as the oil warms. In many cases, oils with wide viscosity
ranges use large amounts of viscosity modifiers that shear (break down) during
use - sometimes rather quickly. Some of these modifiers can build up on the
sides of the pistons, rings, and on other hot parts inside the engine to the
point of reducing oil flow to parts of the engine - not a good thing. This is a
case where if you do not need low viscosity at low temperatures, you are better
served not to use an oil with a large viscosity range (0w- or 5-w-). In the summer, or if you
use a pre-oiler, you will likely be better served with a 10w- or 15w-40 oil with
a narrower viscosity range. Match the oil's weight to the use and needs of the
engine.
On engines with variable valve technology where the
oil pressure is used to control the cam timing and/or a secondary set of cam
lobes, the viscosity and lubricity (and the oil's durability) can make a
difference in how the engine performs and the engine's oil pressure when
running. This is especially important in engines with hydraulic
lifters/tappets.
Synthetic: This no longer means what it used to. A
couple of years ago, Mobile (the manufacturer of most synthetic base
stocks) sued Castrol for using the term synthetic on some of their oils using a
mineral oil base stock with a highly modified additive package. A judge ruled in
Castrol's favor, so now an oil can be called "synthetic" even if it does not
have a synthetic base stock, and can simply be a highly refined mineral base. Castrol's Syntec and Shell's Rotella synthetic are
two of these "synthetic" mineral base oils - among many.
Wear tests: A given oil's ability to protect parts can be seen
in the four ball wear test: Three ½ inch
diameter steel balls are clamped together and covered with
the test lubricant. A fourth ½ inch diameter steel ball is
pressed into the cavity formed by the three clamped balls
for three point contact, and rotated for a set duration.
Lubricants are compared using the average size of the scar
diameters worn on the three lower clamped
balls. Not all four-ball wear
tests (ASTM D4172) are the same, but this is a very good indication of how the
oil protects under use. There are several specs for ASTM D4172 that can be run
at several speeds from 800 rpm to 3600 rpm (or even a variable speed test) but
generally the specs are - speed: 1200 rpm, load: 40kg, time: 60 min.
The Falex pin and block test should be considered as well, other
than many manufacturers do not publish this data.
Gear lubes: These are measured under completely
different specs than engine oils. In fact, a 75w-90 weight gear lube is the same
weight as many 10w-40 or 15w-40 engine oils. GL4 and GL5 refer to the high
pressure, anti-wear properties of the oil. A GL5 lube has better high load wear
protection than GL4 - sometimes this is done by increasing the amount of
specific additives, but not always. Generally speaking, a gear lube has less
tendency to foam, higher crush strength, and better high pressure anti-wear
properties than an engine oil, however, there are several 10w-40 engine oils
that also have GL4 or GL5 ratings.
Oil analysis: This is a great way to check if the
oil you are using meets the needs of the engine and the way you are using it.
Combined with an occasional cutting open and inspecting of the oil filter's
media, this is the best information you will get short of an engine
tear-down. Just do not compare the analysis results from one company to those of another. As in many things, the differences can cause difficulty in direct comparisons.
On the subject of motorcycle specific oils in
motorcycles, not all are the same, and a wet clutch is not as important as the
oil's ability to offer gear protection without breaking down
quickly.
Starting in 2006, oil manufacturers of automotive and diesel oils were required to greatly reduce the ZDDP level in these oils in order to carry the latest government ratings. This was done so that the OEM catalytic converters would last longer - approximately 100,000 miles. Motorcycle specific oils were not altered. ZDDP is a compound of zinc and phosphorus that works as a high pressure anti-wear compound. This means that automotive and diesel oils no longer protect as well as before, and in some cases, camshafts and lifters or tappets have reported a large increase in wear - especially during break in.
Oil filters: Just as with oils, not all filters are the same. There are differences in construction, filtering area, filtering media, flow restriction, and bypass valves.
The bypass valve is usually a spring loaded disc valve at the bottom of the filter that is set to open when the oil pressure exceeds a given pressure. This causes the oil to bypass the filtering media and return to the engine unfiltered. On a cold morning, the oil is thicker at start-up, and the bypass valve can open preventing the internal pressure from causing the filter to burst. But a low pressure bypass can also allow the valve to open at higher rpm - causing unfiltered oil to run through the engine at high rpm. Lower viscosity oil can raise the rpm where the bypass valve opens, or prevent it from opening all together. Generally, automotive filters have bypass valves with lower spring pressures than identically constructed motorcycle specific filters designed for much higher rpm.
Some high flow filters give a nice little gain in power on high rpm engines that is worth considering in max effort performance bikes. In a couple of cases, these filters actually filter better than their more restrictive brethren, making them worth considering on daily ridden bikes as well.
Filter and sump magnets: A strong magnet on the side or bottom of the oil filter can help to attract and hold ferrous (iron based) metallic debris against the inside wall of the filter casing or at the bottom of the sump that would otherwise be collected in the filter media or run through the engine - a bad thing. I generally use a strong rare earth magnet on the side or bottom of the oil filter, and swap it to the new filter during oil changes.
While filter magnets can be purchased from aftermarket companies, I generally just buy a few online from magnet retailers like KJ Magnetics, for considerably less than the aftermarket filter magnets. The strength of the magnet will hold it in place even during spirited sessions of riding, and one needs to simply tape it in place during track days. A side benefit of a strong magnet on the bottom of the oil filter is that it can help to trigger the magnetic strips at stoplights - no more waiting through several light changes.
Using a sump plug with a small rare earth magnet mounted to it can aid as well. These sump plugs are usually available at the local automotive parts store. Pick one up the next time you stop by to purchase a few sump plug crush washers - much cheaper than at the local motorcycle dealer.
Lubricants are not all the same, and the correct selection of lubricant(s) can protect longer, better, and even make a bit more power. Becoming informed on lubricants today is easier than ever. Do your own research, and make your own decisions.
-POWER-TRIPP Performance
