There are certain things to be considered while selecting the engine oil.

Of course, you can use and buy a manufacturer's most recommended easily, but on an established engine and if you are into riding modes other than commuting like Touring or Racing you have to do some fine tuning.

The oils questioned about the Suzuki GS150R most commonly are of grade 20W40 or 15W50.

Remember, first there was trade-off and next there was the all-rounder.

So how to read a motor-oil ???
When it comes to the numbers that describe motor-oil, it is all about viscosity.All the engine oils that are used nowadays are blessed with multi-viscosity grades.
They sport two viscosity grades of operation :
1.Low temperature 2.High temperature
For example in a motor-oil graded xWy.....x= level of viscosity at low temperature and y= level of viscosity at high temperature, but remember they are not temperatures.

The Lower the level of viscosity of a motor-oil at lower temperature, the better would that engine oil flow in cold temperatures.Which means if you go touring in mountains and you have to start your bike over there in morning, your engine-oil with good low viscosity grade would jump into action immediately due to less resistance due to viscosity.This actually helps as the engine does not run dry at start up and avoids unwanted wear and tear.

Now, the question arises, but low viscosity engine oil would suffer at high temperature wont it ????

My answer would be,yes and that is why the engine oil of now-a-days sports multi-viscosity mode.

Now get this factored in that on a vast and fast highway, you want to redline your bike and would love some hard acceleration for a bit of sporty riding out of corners.But all these situations gives rise to high engine levels of engine operations which means higher temperature in the engine.So how the engine oil would hold its place ??? Well,The Higher the level of viscosity of a motor-oil at higher temperature, the better would be the integrity of that engine oil at extreme operation of engine.My actual opinion of an all-rounder engine oil would be,
A fully synthetic 15W50 engine oil, because of the following reasons,
1.Fully Synthetic: better at being a multi-viscosity oil, won't lose its viscosity now and then.While protecting the engine at all times and in any extremes, it is consumed less too.Fully synthetic oil is an engine oil at is maximum capability in its respective grade.

2.Cold viscosity-15W: capable of instant operation even in frozen temperatures, much better at turning the engine at start-up in cold temperatures than the 20W oil.

3.Hot viscosity- 50: Too good a grade for an engine-oil where the engine would be redlined or stressed by extreme operation leading to very high operating temperatures.This rating would help the oil to protect the engine as far as possible without allowing seizure due to viscosity disintegration of engine oil and running the crank dry.

So if I go to ride in mountainous roads with this kind of oil in my bike, it means,I start the bike without any hue and cry outside the hotel in the morning and the engine feels very happy.While negotiating steep climbs revving high in lower gears, the engine would be at ease.While doing a steep descent, under huge amount of engine braking, the engine won't be stressed.
Being fully synthetic means I can keep riding in the mountains till I become a yeti without changing the oil any sooner.
Similarly in the city, cold morning starts and warm-up of engine would be of lesser concern and while going for a fast highway ride,redlining the bike won't tire the engine.
So while riding the more confident would be I in any terrain and in any extremes.
But this all-rounder is to be used only after the engine has done its run-in and has completed the initial 6000kms of its life, otherwise the costly fully synthetic oil has to be replaced now and then as it would be contaminated with debris of initial engine wear.
I can suggest a brand name for the same: Motul 300 V 15W50 Fully Synthetic.

So use the 20W40 mineral so long as 5000kms till the bike has set its engine in well.
And if you want the advantage and extend the engine life and ready to spend some to gain some,switch to 15W50 full-synth.


Now, the trade offs type of engine oil.
The grades that shouts 5W30 or 10W40 or semi-synthetic are compromised type of oils.
1.5W30 means more than enough low temperature performance, but where is the advantage at high levels of engine operations ???

2.10W40 good low temperature performance but not enough for prolonged high temperature uses.......does not promise any significant advantage...does it ???

3.Semi-synthetic- costs higher than the mineral oil but performance and life at par to the mineral oil, so why spend more ???


So now you know the basics, I think you all can now decide what is good and better for your kind of riding.

One more thing,sometimes there you would find some brand statements like Ester or Double Ester.......well an Ester is a chemical compound to begin with and it is used as an additive to integrate viscosity at higher temperatures.It betters engine oil quality.Thats all.

Just make sure that the engine oil is labeled JASO MA2.As the engine meets specifications for use of this kind of oil.

If you ask me for company,I would always prefer Motul,next would be Elf and I don't know about Shell,Gulf,Servo,Mak,Mobil and all but Castrol is one engine oil I would better avoid.It makes the engine feel like survivng and not living.

Hope this post of mine helps every Suzuki owner and all other Bikers who follows our thread.

which oil is best for GS at this stage..?

surely wil now go for 15w50.

OT:OK, Agreed,more than 50% GS150Rs gets more mileage than a 125cc bike,Still,don't you all think its high time the poll be closed?

Only steering alignment of the bike has lost, my mechanic is goin to realign tomorow, so what do u suggest regarding oil, shall i change now?? coz u mentioned its better to change it after 5000kms.

It is advised to replace the oil in every 4000 kms or 100 days, whichever is first. Replace it now and replace the handle bar if it is bent. You will get it for Rs. 200/-.

The best oil for GS is 20W-40 as suggested by the manufacturer. If you ever change the type of oil, use the same grade oil or one which is near to it. Never use 10W-30 which is very thinner than 20W-40 at the time of starting the bike and at 100 o C, the maximum temperature the engine reaches while riding. And avoid xxW-50 oils too.
At the time of first servicing, ensure that the oil filter is replaced with the oil and all the nuts and bolts, especially the engine mounting and chassis bolts, are retightened at correct torque. Ask them to clean the air filter too.
Never tell them that the mileage is poor as the first thing they do is adjusting the air-fuel ratio. Do not alter the carburettor settings.
The sound you hear is due to the looseness of the chain. Get it tightened.

Today, i gave my bike to the SC... well, what you said is right.. the sc guys told me the sound is due to Chain.... and the engine oil, they said they will provide castrol... but i said not to use castrol..and gave them Motul 3000 4T 20W40.. But they were telling they will give warranty for castrol but not for anything else.. Is there anything like that?? :O Still i told them to use motul only..

But what am worried is how will i make sure they have used the one i gave them..what if they are still re-filling castrol only... ..

and they asked me whether to do teflon coating or not..( cost rs 550 and one free coating @ 5th or 6th service) . . Will it really make any difference, using teflon coating ?

which 20w40 oil should i use?

But they were telling they will give warranty for castrol but not for anything else.. Is there anything like that? O Still i told them to use motul only.

as oil change is concerned, always try to be there at the place when they change the oil, specially in your case where u insisted using a third party oil.

1. You can fill any brand oil as you like without affecting the warranty. The SC is selling Castrol oil for their profit.
Buy an oil filter from the SC, collect 17 and 8 mm socket spanners and replace the oil and filter yourself. After that, please let me too know why you don’t like Castrol oil.
Except some of the GS owners active here and perhaps some others replacing the oil themselves are using Castrol oil provided at the SC. Never heard about a bike’s engine being damaged of using that oil or about any bike flying in the air after filling any other oil.

i dont have any experience in changing oil and all by my own.. but have to try it out later on.

Genuine Castrol is as good as any other brand; sadly as castrol is the #1 selling brand in india more duplicate castrol oils are there in the market
am not using castrol because i prefer to use a oil with JASO MA2 standard

I have been using Shell Ultra Advance 10w40 Fully Synthetic(Rs.796 at Shell Fuel station-JP NGR) and i am totally satisfied with the smoothness of gears and the engine sound. I feel Overall the whole bike's sound and feel is smoother compared to all other Oils(Mineral - Castrol, Shell) that i have used so far.


An Info which might help all of us who want to get our GS converted to full DC. Had been to Ruby Electricals(Near Lalbagh, Bangalore) who can convert most of the bikes to full DC and for our GS 150, we might have to shell around Rs.1500 excluding Regulator's price. During my visit the elder person at the shop informed me that i can't get it done on that day as he didn't had the guys present at shop and wanted me to give them a call and get a confirmation before coming.