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Which Oil?

Discussion in 'Maintenance and Servicing' started by Enrgkid, Jul 24, 2013.

  1. Okay so My bike is due for an oil change and checking my manual I can use either 10w40, 20w40 or 20w50.

    My issue is will it make a difference, and I'm looking for semi synth oils, is that the right choice? or should I look for fully synth?

    I know probably a noob question, But I was really hoping someone on here might be able to help.


  2. simple answer..

    the first number is the 'weight' of the base oil. If the engine is old, tired and worn then opting for a heavier base oil is possibly a good idea.

    15W-40, which is a very common grade, could also be added to the list of choices.

    This chart pinched from a workshop manual may help you make a choice. Shows the range of temperatures that a particular oil viscosity range is suited to.
    oil viscocity v temp range.
  3. #3 twistngo, Jul 24, 2013
    Last edited: Jul 24, 2013
    I like motul 5100 which comes in 10W40 (and 10W50)
  4. So the 20w 40 not a bad idea?
  5. for my bike its 10W40 or 15W50. it gets cold down here in melb.
  6. I wanted some of that 10w40 motul sat time I bought oil but they only had 20w50 so I went for the 7100 10w40.

    So since we're discussing oils, Apart from the price can someone tell me the diff between 5100 & 7100 at the same viscosity rating ?
  7. #7 Wil02, Jul 25, 2013
    Last edited: Jul 25, 2013
    Ummm so some parts of sydney metro area were 2 degrees or less and a 20w oil is rated from temps >0, say 1 or 2 ? by that chart.

    So then if you decide to travel, let's say you do an over nighter to say any of bowral, Bathurst, lithgow or parkes, just as examples and all of which are imo good riding destinations it's been less than 0 degrees this morning.
  8. 5100 = semi synthetic

    7100 = fully synthetic

    for most the 7100 is overkill especially if you are sticking it in a LAMS bike, and if your bike is still young a mineral based oil is probably better for it.
  9. 10W-40 during winter and 20W-50 during summer. 20w will not flow well during cold morning start ups. A good quality 10W-40 maybe okay for all year round use.
  10. 10w40 is probably the best grade for year round suitability for the majority of bikes.
    Have used motul 5100 & 7100, and after seing what the oils are like comming out of engines after 10,000km, I'd recommend the 7100 every time. The 5100 seems to turn black much quicker. The 7100 still looked good. Yes it is overpriced, but damn it's good.
    It may be more cost effective to use a mineral oil & change it more frequently, if you are just commuting & taking it easy. But if you are in the habbit of thrashing the poor little thing, then perhapps treat it with some synthetic.
  11. #11 CraigA, Jul 27, 2013
    Last edited: Jul 27, 2013
    My understanding of multi grade oils is slightly different.

    Lets say you use a 10W-40. The W stands for Winter weight or the weight of the oil when cold, not the weight of the base oil.
    What 10W-40 translates in terms of a multigrade oil to is an oil which will flow like 10 weight oil while cold, allowing it to flow quickly to protect engine components but once warm it thickens to act like a 40 weight oil which is more ideal once operating temp is reached.

    In other words, unlike normal oil or liquid which becomes less dense when warmed, a multigrade oil becomes more dense when temps rise.
  12. #12 mike8863, Jul 28, 2013
    Last edited: Jul 28, 2013
    OK, you want the long answer....

    Motor Oil Viscosity Grades

    What does the SAE Viscosity rating on your Motoroil bottle mean?
    How do they come up with this rating . . .really?

    Most of the time when viscosity is explained words are used that are too technical for the average person to quickly grasp. This leaves them still wondering what the viscosity numbers really mean on a bottle of motor oil. Simply put, viscosity is the oil's resistance to flow or, for the layman, an oil's speed of flow as measured through a device known as a viscometer. The thicker (higher viscosity) of an oil, the slower it will flow. You will see oil viscosity measurement in lube articles stated in kinematic (kv) and absolute (cSt) terms. These are translated into the easier to understand SAE viscosity numbers you see on an oil bottle.
    OK . . .What does a 5W-30 do that an SAE 30 won't?
    When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. The numbers without the W are all tested at 210° F or 100° C which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210° (100° C). The difference is when the viscosity is tested at a much colder temperature. For example, a 5W-30 motor oil performs like a SAE 5 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210° F (100° C) which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear.

    oil viscosity chart.
    Obviously, cold temperature or W ratings are tested differently than regular SAE viscosity ratings. Simply put, these tests are done with a different temperature system. There is a scale for the W, or winter viscosity grades and, depending on which grade is selected, testing is done at different temperatures. See the Tables to the right below for more information.
    Basically to determine non-winter grade viscosity using a viscometer a measured amount of oil at 100° C is allowed to flow through an orifice and timed. Using a table they determine SAE viscosity based on different ranges. Thicker or heavy viscosity oils will take longer to flow through the orifice in the viscometer and end up in higher number ranges such as SAE 50 or SAE 60 for example. If an oil flows through faster being thinner/lighter then it will wind up in a low number range such as SAE 10 or SAE 20 for example. Occasionally it is possible for an oil to barely fall into one viscosity range. For example, an oil is barely an SAE 30 having a time that puts it on the very low side. Then another oil is timed to be an SAE 20 on the high side not quite breaking into the SAE 30 numbers. Technically speaking these oils will be close to the same viscosity even though one is an SAE 20 and the other an SAE 30. But you have to draw the line somewhere and that's how the SAE system is designed. Another system takes more accurate numbers into account known as cSt abbreviated for centistokes. You'll see these numbers used often for industrial lubricants such as compressor or hydraulic oils. The table at the right, SAE Viscosity Chart (High Temp), shows the equivalents for cSt and SAE viscosity numbers. You'll see the ranges for cSt compared to SAE numbers. An oil that is 9.2 cSt will be nearly the same viscosity as an oil that is 9.3 cSt, yet one is an SAE 20 and the other is an SAE 30. This is why the cSt centistokes numbers more accurately show oil viscosity.
    Now if you look at the table labeled Winter or "W" Grades, you can get valuable information on how the W or winter grade viscosities are measured. Basically, as shown by the chart, when the oil is reduced to a colder temperature it is measured for performance factors. If it performs like a SAE 0 motor oil at the colder temperature, then it will receive the SAE 0W viscosity grade. Consequently, if the motor oil performs like a SAE 20 motor oil at the reduced temperatures (the scale varies - see the chart), then it will be a SAE 20W motor oil.
    If a motor oil passes the cold temperature or W (winter grade) specification for a SAE 15W and at 210° F (100° C) flows through the viscometer like a SAE 40 motor oil, then the label will read 15W-40. Getting the picture? Consequently, if the motor oil performs like a SAE 5 motor oil on the reduced temperature scale and flows like a SAE 20 at 210° F (100° C), then this motor oil's label will read 5W-20. And so forth and so on!
    I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin."
    So how do they get a motor oil to flow in the cold when it is a thicker viscosity at 210° F?
    The addition of Pour Point Depressant additives (VI) keep the paraffin in petroleum base oils from coalescing together when temperature drops. Pour Point Depressants can keep an oil fluid in extreme cold temperatures, such as in the arctic regions. We will not go into Pour Point Depressing additives at this time except to say they are only used where temperatures are very extreme to keep the motor oil from becoming completely immobilized by the cold temperature extreme. For now we will just discuss the Viscosity Improvers (VI) additives.
    Why don't we just use a SAE 10 motor oil so we can get instant lubrication on engine start up?
    The reason is simple: it would be a SAE 10 motor oil at 210° F! The lower the viscosity, the more wear will inevitably occur. This is why it is best to use the proper oil viscosity recommended by the auto manufacturer as it will protect hot and at cold start ups. Obviously a 10W-10 motor oil won't have the film strength to prevent engine wear at full operating temperature like a 5W-20, 10W-30 or 5W-30 motor oil for example.
    The VI additives have the effect of keeping the oil from thinning excessively when heated. The actual mechanics of this system are a little more complex in that these additives are added to a thinner oil so that it will be fluid at a cold temperature. The VI additives then prevent thinning as the oil is heated so that it now can pass the SAE viscosity rating at 210. For example; if you have a SAE 10 motor oil it will flow like a 10W at the colder temperature. But at 210 degrees it will be a SAE 10 giving us a 10W-10 or SAE 10 viscosity rating. Obviously this is good at cold start up, but terrible at engine operating temperature especially in warmer climates. But by adding the VI additives we can prevent the oil from thinning as it is heated to achieve higher viscosity numbers at 210 degrees. This is how they make a petroleum based motor oil function for the 10W-30 rating. The farther the temperature range, like with a 10W-40, then more VI additives are used. With me so far? Good, now for the bad news.
    Drawbacks of Viscosity Improving additives
    Multi-grade motor oils perform a great service not being too thick at cold startup to prevent engine wear by providing more instantaneous oil flow to critical engine parts. However, there is a draw back. These additives shear back in high heat or during high shear force operation and break down causing some sludging. What's worse is once the additive begins to be depleted the motor oil no long resists thinning so now you have a thinner motor oil at 210 degrees. Your 10W-30 motor oil can easily become a 10W-20 or even a SAE 10 (10W-10) motor oil. I don't have to tell you why that is bad. The more VI additives the worse the problem which is why auto manufacturers decided to steer car owners away from motor oils loaded with VI additives like the 10W-40 and 20W-50 viscosities.
    The less change a motor oil has from high to low temperatures gives it a high Viscosity Index. Synthetic motor oils that are made from Group IV (4) PAO base stocks have Viscosity Indexes of more than 150 because they are manufactured to be a lubricant and don't have the paraffin that causes the thickening as they cool. But petroleum based motor oils (Group I (1) & II (2)) usually have Viscosity Indexes of less than 140 because they tend to thicken more at the colder temperature due to the paraffin despite the addition of Viscosity Improving additives. The higher the Viscosity Index number the less thinning and thickening the motor oil has. In other words, high number good, low number bad. Low numbers thicken more as they cool and thin more hot. You see these Viscosity Index ratings posted on data sheets of motor oils provided by the manufacturer.
    As already mentioned, VI improving additives can shear back under pressure and high heat conditions leaving the motor oil unable to protect the engine properly under high heat conditions and cause sludging. Also there is a limit to how much viscosity improving additives can be added without affecting the rest of the motor oil's chemistry. Auto manufacturers have moved away from some motor oils that require a lot of viscosity improving additives, like the 10W-40 and 20W-50 motor oils, to blends that require less viscosity additives like the 5W-20, 5W-30 and 10W-30 motor oils. Because stress loads on multi viscosity motor oils can also cause thinning many racers choose to use a straight weight petroleum racing motor oil or a PAO based Synthetic which do not have the VI additives. But only the Group IV (4) PAO based synthetics generally don't need VI additives. Read on to learn why:
    What about synthetic motor oils? Do they need Viscosity Additives?
    Group IV (4) and Group V (5) base oil (synthetics) are chemically made from uniform molecules with no paraffin and generally don't need Viscosity Additives. However, in recent years Group III (3) based oils have been labeled "synthetic" through a legal loophole. These are petroleum based Group II (2) oils that have had the sulfur refined out making them more pure and longer lasting. Group III (3) "synthetic" motor oils must employ Viscosity Additives being petroleum based.
    Group V (5) based synthetics are usually not compatible with petroleum or petroleum fuels and have poor seal swell. These are used for air compressors, hydraulics, etc. It's the Group IV (4) PAO based synthetics that make the best motor oils. They are compatible with petroleum based oils and fuels plus they have better seal swell than petroleum. Typically PAO based motor oils use no Viscosity Index additives yet pass the multi-grade viscosity requirements as a straight weight! This makes them ideal under a greater temperature range. One advantage of not having to employ Viscosity Improving additives is having a more pure undiluted lubricant that can be loaded with more longevity and performance additives to keep the oil cleaner longer with better mileage/horsepower.
    How do I know what motor oil is a Group IV (4) based PAO synthetic motor oil?
    As more and more large oil companies switched their "synthetic" motor oils to the less expensive/more profitable Group III (3) base stocks it has become much easier to identify which are PAO based true synthetic. Of the large oil companies, only Mobil 1 Extended Performance, as of this writing (12-16-2012), is still a PAO based true synthetic. The rest, including regular Mobil 1 and Castrol Edge have switched to the cheaper/more profitable Group III (3) petroleum based "synthetic" motor oil. AMSOIL Synthetic Motor Oils are PAO based true synthetic motor oils with the exception of the short oil drain OE and XL synthetic motor oils sold at some Auto Parts Stores and Quick Oil Change Centers. This leaves more than 20 PAO based true synthetic motor oils manufactured and marketed by AMSOIL with only a few Group III (3) based synthetic motor oils identified by the "OE" and "XL" product name.
    So as you can see, the average performance of motor oils can be affected by how they change during their service life. Multi grade petroleum can lose viscosity and thin causing accelerated wear as the VI additives shear back. Straight weight petroleum (i.e. SAE 30, SAE 40) thicken a lot as they cool meaning longer time before lubricant reaches critical parts on cold starts, but have no VI additives so they resists thinning. However, they can degrade and thicken as heat and by products of combustion affect the unsaturated chemistry. Group III (3) synthetics resists this degradation much better, but being petroleum based employ some VI additives which is a negative and typically don't have as good performance in the volatility viscosity retention areas. Only the Group IV (4) PAO base synthetics have the saturated chemistry to resist degrading when exposed to the by products of combustion and heat, plus typically employ no VI additives making them very thermally stable for longer periods. For this reason the Group IV (4) synthetics maintain peak mileage and power throughout their service life
    Modern motor oils are a marvel of chemistry to be sure. There are a lot more additives in play than the few mentioned here. The API (American Petroleum Institute - sets oil standards in the U.S.), ILSAC (International Lubricants Standardization and Approval Committee - U.S. & Japanese auto/truck manufacturers standards for motor oil) and ACEA (Association des Constructeurs Europeens d'Automobiles - European auto/truck manufacturer oil standards) are some of the different organizations you will see providing rating information on the service grades of different motor oils. Plus there are some auto manufacturers like Mercedes, BMW and Volkswagen that have unique oil standards for their cars. You need to read your owner's manual clearly to be sure you are using the proper oil for your application.
    Some of these organizations, such as the API and ILSAC, have reduced friction modifier amounts in order to extend the life of catalytic converters and reduce pollution. These will increase wear but will be still within the "acceptable wear" range. Because of the increased wear and expense of licensing these oils some companies will not certify for API & ILSAC in order to achieve a higher level of performance. People with older engines that do not have roller cams find these oils especially attractive to maintain a reduced level of engine wear. AMSOIL only has 5 motor oils certified for the API & ILSAC for this reason (the four XL-7500 Branded motor oils and the semi-synthetic 15W-40 PCO). The rest of the nearly 30 synthetic motor oils are not certified in order to maintain the higher levels of friction modifier to maintain the enhanced level of performance necessary for their targeted market. In other words, the less expensive motor oils made by AMSOIL are API & ILSAC certified while the high end more expensive performance motor oils are not. One reason companies like AMSOIL and Mobil are at odds with the reduced friction modifier standards is they don't take into consideration the reduced volatility of PAO based motor oils which leads to much less pollution and thereby less problems for the catalytic converter. Even with the full wear preventing additives these oils do not produce the pollution of petroleum motor oils. For this reason AMSOIL has left the friction modifier levels high and skips certification for these higher performing motor oils. For more information read the Motor Oil Quality Progresses With Engine Technology (Good information on motor oil service ratings) and Why does Motor Oil Deteriorate?
    For more information also see:
    Credits : This article has been sourced from the Amsoil website.
  13. No just the correct answer in a succinct form would have done us all fine!
    Your first attempt was incorrect. Nowhere in your copied and pasted long answer could I see anything about the base oil being the lower number, which is what you first posted. This was misleading and not correct.
    They talk about winter and cold viscosity but not the viscosity of the base oil being represented by that lower number on a multigrade oil.
    They haven't stated that W is for weight either which is what you 'eluded' to.

    The lower number on multigrade oil is its cold viscosity. The high number is its viscosity at operating temp. That's all you had to say.

    The chart you initially posted was good though. It shows us that unless you operated your bike below minus 15c or above 45c, a 10w-40 oil is probably going to suit most situations here in oz.
  14. It all boils down to the fact that for road vehicles on Aust roads there is little difference which oil is used if it meets the recommended specs for that vehicle. Just up to the owner how much money they want to waist. A high performance vehicle on a race track is a different situation.
  15. if you do regular services & are'nt floggin the ring out of it Castrol 4T is all you need
  16. Ive used Motul semi synthetic i believe, 5100 10w30 and i had some clutch slippages.
    Now recently ive used another brand, which is considered overkill for me cb125e, its an Amsoil 10w30, i really like it. No slipping of clutches as of yet.
    So even though its costs a bit more, for this bike it takes less than a litre to use... its just worth it for me.