Engine Oils

[Pinaki]

You have got the myth wrong way , contrary to popular belief the viscosity of multi-grade oil does not increase with temperature . It decreases , i.e it gets thinner and thinner with rising temp , just like any other oil . It's really long thing to type here (again!) , read it up . Do you know of any substance that gets thicker with heat ?

[muztariq]

i hope you got your answere from the last post of mine.. 10w oil will not get thinner but will get thicker at operating temperatue and how much thick it gets depends on the wXX rating.
In summers your bike will encounter max 40 deg C outside temp. Inner temp is 100 deg celcius. In winters your bike will encounter 5 degree celcius outside and inner remains 100 deg celcius. In winters your oil will be more towards colder side i.e more thinner and in summers it will be more towards higher side i.e more thicker.. As the operating temp increases in summers the clearances also become wider.. It is safer to use w40 in place of w30 then, but it is not at all dependant on oil viscosity.. If your bike is not consuming oil in summers there should be no reason for you to switch to thicker grades as your FE will come down and also you will be less protected as the thicker oil will not penetrate the vital parts of your engine (as per recommendation from manufacturer). The main reason for old oil getting less functional is it increases in viscosity. And you are intentionally increasing this viscosity i dont kniw why!

[sachin1111]

Muztariq, oil that flows easily is called thinner oil and oil that does not flow easily is the thicker oil. when oil gets heated its viscosity reduces and it becomes thin. for example water is thinner then oil.now if you are saying that oil becomes thicker with increase in temperature then at high temperature engine oil would turn in to something like Gee or grease.

[muztariq]

You have got the myth wrong way , contrary to popular belief the viscosity of multi-grade oil does not increase with temperature . It decreases , i.e it gets thinner and thinner with rising temp , just like any other oil . It's really long thing to type here (again!) , read it up . Do you know of any substance that gets thicker with heat ?

if you have got it all wrong from the starting what can i do :-)
its time for you to read now sir! Read about viscosity modifiers..
Multi grade oils behave different!! Thats why they are there :-) otherwise i would have used kitchen oil in my bike.
When you start your bike oil should be thin so that it can flow! But this thin oil cant protect your bike that much, thats why it is recommended to warm up the engine before speeding! So that it reaches its optimum temperature and viscosity
hope you get the point.

Viscosity modifiers make an oil's viscosity higher at elevated temperatures, improving its viscosity index (VI). This combats the tendency of the oil to become thin at high temperature. The advantage of using less viscous oil with a VI improver is that it will have improved low temperature fluidity as well as being viscous enough to lubricate at operating temperature. Most multi-grade oils have viscosity modifiers. Some synthetic oils are engineered to meet multi-grade specifications without them.
Just cut copy pasted the last paragraph from wikipedia- as i am typing from phone couldnt copy the webpage address.. I hope you will google to find out the source.

[muztariq]

Muztariq, oil that flows easily is called thinner oil and oil that does not flow easily is the thicker oil. when oil gets heated its viscosity reduces and it becomes thin. for example water is thinner then oil.now if you are saying that oil becomes thicker with increase in temperature then at high temperature engine oil would turn in to something like Gee or grease.

why will it convert into ghee when a very calculated amount of viscosity modifier is added.. Thats what science is. It cant go above the tested value of w40 or w50 whatever the case may be..

[sachin1111]

why will it convert into ghee when a very calculated amount of viscosity modifier is added.. Thats what science is. It cant go above the tested value of w40 or w50 whatever the case may be..

Download this twister user manual and read page 46...Honda has given a graph which shows optimum working temperature of 10W30 and 20W40 oils.
Owner's Manual Twister

you are basically considering lower temperature range of oil but not considering optimum higher temp range.

[Honda_CBF]

why will it convert into ghee when a very calculated amount of viscosity modifier is added.. Thats what science is. It cant go above the tested value of w40 or w50 whatever the case may be..

buddy, you got the whole idea of VI's wrong.. They are used to prevent an oil getting "too thin" under high temp not the other way round.

[psr]

A 10 w 30 oil has the Base oil of 10 grade at cold temperatures upto -20 C and at 100 C has the same viscosity that a 30 grade oil will have at 100 C.
similarly the 20 w 40 oil will have a base oil of grade 20 till - 10 C, and will have the same viscosity that a 40 grade oil will have at 100 C.
All engine oils become thin with heat and so additives are added to decrease the thinning effect.At no time can a 10w30 oil become 30 grade at 100 C.
The more the additives, the greater the cold to hot range, and more the likely hood of engine oil becoming bad with heat stress...this is particularly applicable to Air cooled engines which are purely dependent of available air to cool the engine.

[muztariq]

buddy, you got the whole idea of VI's wrong.. They are used to prevent an oil getting "too thin" under high temp not the other way round.

yes, you are right. I am comparing viscosity of corresponding grade single grade oil.
When you put a multigrade oil.. The starting viscosity may be thin or thick depending on the temperature difference its having like 5w30 is thinner than 10w30 at starting temperature. When the temperature rises it does not get any thinner than a single grade w30 oil i.e it is having viscosity improvers which prevent further thinning.

[abhinavsri01]

Abhinav'jee, castrol power 1 doesn't not match recommended grade for your bike since it is not 20w40 . Try Motul/Gulf/Elf/Yamalube etc, plenty of good 20w40 motorcycle oils around .

Thankyou Pinakiji.. Will look for Motul or Gulf this time. Any specific one??

shell advance ultra - 10w40 750 rs. Lasts 5000 km/ six months.

Thanx buddy.. But there are no Shell bunks here & I have not seen any stockist with Shell oils.

[muztariq]

Download this twister user manual and read page 46...Honda has given a graph which shows optimum working temperature of 10W30 and 20W40 oils.
Owner's Manual Twister

you are basically considering lower temperature range of oil but not considering optimum higher temp range.

a clear example of the recommendation.. It doesmt mean that you get a lower viscosity grade in winters and higher grade in summers.
Choose a grade as per your ambient temperature.. No where you will find a difference of more than 45deg C between summer and winter temp.
If your manufacturer recommends using 20w40 you can easily use 15w40 grade oil. The only problem you will encounter that this oil will have slightly more additives than 20w40. If you use a synthetic 10w40 grade synthetic oil then the additive level will be negligible as synthetics doesnt require viscosity modifiers, they are made to satisfy both requirements.

[Pinaki]

yes, you are right. I am comparing viscosity of corresponding grade single grade oil.
When you put a multigrade oil.. The starting viscosity may be thin or thick depending on the temperature difference its having like 5w30 is thinner than 10w30 at starting temperature. When the temperature rises it does not get any thinner than a single grade w30 oil i.e it is having viscosity improvers which prevent further thinning.

VIIs are polymers with tightly coiled molecules , which uncoil when heated . As they uncoil , they make the oil stick to the metal surface better . Think of some sawdust and oil mixture .i,e they prevent the oil from flowing away from the metal thereby preventing breaking the oil-film when hot . Baas , that's it . They do not make the oil thicken when hot . If you don't believe it take some multigrade oil in test tube(or any small container) and heat it and examine it's thickness and flow(pour)properties in both hot and cold conditions . A rudimentary visual and physical experiment like this will clear you doubts .I have tried it .
VIIs don't have any lubricating properties at all . Neither do they conduct heat well.Those desirable properties come from the base-oil used in the multigrade . Additionally VIIs easily decompose(like other polymers) and form sludge inside the engine . More VII also means less actual oil in the amount that your engine can contain .

Thankyou Pinakiji.. Will look for Motul or Gulf this time. Any specific one??

I am getting motul here , many others are using gulf's or yamalube etc , not any big difference .. get whatever is reliably available cheaper near you . Like I bought Honda's OEM 20w40 oil to try out this time . This splendor is kinda my trying things out bike since it's quite simple to tinker with and cheap to repair and run .

[Pinaki]

a clear example of the recommendation.. It doesmt mean that you get a lower viscosity grade in winters and higher grade in summers.
Choose a grade as per your ambient temperature.. No where you will find a difference of more than 45deg C between summer and winter temp.
If your manufacturer recommends using 20w40 you can easily use 15w40 grade oil. The only problem you will encounter that this oil will have slightly more additives than 20w40. If you use a synthetic 10w40 grade synthetic oil then the additive level will be negligible as synthetics doesnt require viscosity modifiers, they are made to satisfy both requirements.

[muztariq]

trying to understand what you mean to say. What would you recommend in winters and summers for these manufacturer recommendation in your area 9-45!
1) 10w30
2) 20w40
3) 20w50

[ashwinprakas]