[srini1785]

Originally Posted by Jeroen

When it comes to the original question: I don’t see the type of cooling making a huge difference perse. The biggest difference between the bike and the car when it comes to oil, as mentioned already I would think: On a bike you will often have the same oil doubling up for the clutch and transmission as well. Combine that with a relative small volume of oil to engine volume and power compared to your typical car.


So the oil on an bike needs to “work” much harder on more moving and wearing parts than in a typical car engine.

Yes they are engineered for such operation. However i know of certain (older) bikes where oil is stored externally and not inside the engine case. This brings us to the topic of Wet and dry sump lubrication. While dry sump lubrication looks good on paper , most modern bikes (and cars) have changed to wet sump lubrication.

Originally Posted by Jeroen

Also, but I have never checked this, just a gut feeling; Are typical bike sumps a lot smaller relative to the engine size comparing them to cars. i.e. do bikes relatively speaking have less volume of oil to start with? My little Alfa Spider, 110 BHP, 2.0L engine has 6 liter of oil!
On most modern car the volume of engine oil has come down, but still. What is the average ratio quantity of oil to engine volume/BHP on bikes?

A typical 100-200cc bike has a sump capacity of 1-1.5L. A 900 cc Kawasaki Z900 uses approx 3.5-4L oil. Extrapolating to 2L engine of a Alfa Romeo spider , you may well end up with 6L. However i am yet to come across a 2L bike.

[Gansan]

Originally Posted by Gansan

4) The engine oil also doubles as transmission oil. Because the engine and gear box are a single unit.

This is why one should not use car engine oils in bikes, and buy Motorcycle specific oils. If you want to use Shell Helix, buy the one that carries a bike picture.

The car oils will have certain components which will not be included in the bike oils. If one uses car oils in bikes, pretty soon the clutch will start slipping.

[sagarpadaki]

Originally Posted by Gansan

This is why one should not use car engine oils in bikes, and buy Motorcycle specific oils. If you want to use Shell Helix, buy the one that carries a bike picture.

The car oils will have certain components which will not be included in the bike oils. If one uses car oils in bikes, pretty soon the clutch will start slipping.

True. However there are many people who use diesel/petrol engine oils in bike and are happy with it.

[audioholic]

Originally Posted by Gansan

This is why one should not use car engine oils in bikes, and buy Motorcycle specific oils. If you want to use Shell Helix, buy the one that carries a bike picture.

Shell markets bike oils as Advance and car oils as Helix. Hence there would be no confusion in that regard. While the oils for bikes are in the series AX3, AX5, AX7 etc, car oils come with the HX nomenclature. Yes and never mix their uses.

[Rocketscience]

Well with my logic there are 3 reasons

1- They revv much higher than car engines, leaving aside a few obviously.

2- Pure greed of Bike companies, the same reason some car companies like Honda used to have 5000 kms/6 months service interval while most others had 1 year, does Honda have much inferior quality engines which require more frequent services, of course not. Hell even Honda has updated its service interval schedule now, have they updated the engines of the same cars? We all know the answer.

3- Lack of education - Not to offend anyone but anyways anyone here should not be offended since we all are enthusiasts here but an average 2 wheeler buyer is much less educated or if not that then less informed than an average car buyer.

I follow my own service schedule with my bike, since i do not cover the requisite kilometers i have kept mine simple to every 6 months, because motorcycles do require other inspections like lubrications of cables, chain slack adjustments etc, mine is a particularly high revving bike too, the company however recommends 3 months/3000kms. If i was covering the required kilometers i would have done it 6 months/5000Kms in my bike.

[Gansan]

Originally Posted by sagarpadaki

True. However there are many people who use diesel/petrol engine oils in bike and are happy with it.

Originally Posted by audioholic

Shell markets bike oils as Advance and car oils as Helix. Hence there would be no confusion in that regard. While the oils for bikes are in the series AX3, AX5, AX7 etc, car oils come with the HX nomenclature. Yes and never mix their uses.

There is never any confusion. All companies market both oils in distinct packs. But I have seen people buying Helix synthetic oil and using it for car and bike. Many seem to think it is better. They buy a large pack, fill the car and use the balance for the bike.

[Sportztourer]

Bajaj claims 10000km drain interval with their 'Bajaj DTS-i 10,000' engine oil. Bajaj recommends after 1st service the oil change intervals are at 10000km with DTS-i 10000 engine oil.
I personal prefer the 3000km mark even with synthetic oils on my motorcycles as I have got heavy use (long distance runs). I have done a few lab tests (oil condition monitoring with spectrographic analysis) on used oils and found motorcycle oils do have service life of more than 3000km but this statement cannot be made generic to all oils as a lot depends upon type of engine oil (base stock and additive package) and its running conditions. According to industrial maintenance, oil change comes under preventative maintenance so even if you stretch the drain interval by a 500km, possibilites are low that it will damage the engine. A seasoned rider will start to observe change in gear shift quality and change in NVH from engine as the oil starts to show its age.

[sagarpadaki]

Originally Posted by Sportztourer

Bajaj claims 10000km drain interval with their 'Bajaj DTS-i 10,000' engine oil. Bajaj recommends after 1st service the oil change intervals are at 10000km with DTS-i 10000 engine oil.
.

That works only if you keep topping up the oil every 2000 kms. Else all the oil in the sump will be consumed before 5000 kms the engine will seize up!

PS- Your oil review of various oils is very informative on YouTube

[Jaggu]

Most of the points that are mentioned do contribute, but the main reason for a short change interval Vs long term is the sump capacity, again what I have read and makes sense. Dirt bikes are a classic example where they have short sumps to aid ground clearance and agility but very short oil change intervals.

[bj96]

Some very good answers already in the thread. Few other aspects:

1) Commuter two-wheelers are made to cost and space. Usually, there is not enough space to mount liquid cooling hardware (fan, radiator, pump, thermostat) on a commuter two wheeler. So they run hotter, needs more frequent oil change.

1.a) Less hardware makes the entry cost (purchase price) low and also less things to maintain. Oil is part of maintenance, which customers pay, doesn't impact manufacturers bottom line, hence, not enough incentive for manufacturer to add these.

1.b)Goal of commuter two wheelers is to keep the kerb weight as light as possible for maximum fuel efficiency

2)Traditionally, in most cars, radiator fan was driven by engine timing belt until DC fans came in picture. It would have been complicated to drive this fan on two wheelers from engine belt. DC system in two wheelers came much later

However, newer two wheelers e.g. my 2017 Fat Boy although air-cooled has oil change interval of 8000 miles (in US) and 10,000 kms in India (hotter and dusty country). This monster gobbles up 6.5 litres full synthetic.

Originally Posted by Jaggu

... the sump capacity, ... short sumps to aid ground clearance...

Very interesting point. Harley sure couldn't manage a 7 litre wet-sump tank, so they have a separate oil tank mounted on the frame below seat .

-BJ

Edit: #3) Commuter two wheelers usually designed to do short trips unlike cars- heating and cooling oil two frequently, probably affecting the chemistry to degenerate faster?

[NiInJa]

I used to change my FZ16's oil with the cheapest one available (I think 250 Rs per 900 ml/1 litre Shell Yellow colored can ) and the bike would start getting gruff at higher rpms after 2000-2500 kms of ride. Same case with my Activa, I have ridden the scooter for 5000 kms without oil change and it was too rough by the time it went for a service. It definitely needs to be changed earlier than cars for some good reasons mentioned in the above posts. Maybe scooters/commuter bikes are used for short duration and not at optimal operating temperatures most of the times ?

Of-course, things do get better with high quality engine oils, but spending 1000 Rupees for a can of oil on a commuter bike can be a sort of overkill for many.

[Motard_Blr]

Engine oil is mostly base oil. But a significant amount of the engine oil (10 - 30%) consists of various additives that are used for the following, but not limited to:
To improve viscosity characteristics at low and high temperatures
To reduce engine wear
To clean the engine (detergents)
To reduce engine corrosion
To reduce oil oxidation and sludge formation
To reduce to oil foaming
To prevent water from forming an emulsion with the oil

These additives are actually "consumed" by the engine as it runs.

I have shown a simplified calculation showing why engine oil needs to be replaced more frequently in motorcycle engines.

I will compare a typical 1000 cc car and 125 cc motorcycle used in urban conditions. Let's say that the average constant speed is 30 km/h - typical urban conditions.

To run 1000 km at that speed, the engines would have to run 33.33 hours.

At that speed, the car engine might run at 1800 rpm in 2nd or 3rd gear. So the engine would rotate about 36 lakh revolutions.

At the same speed, the bike engine might run at 3000 rpm in 3rd or 4th gear. This engine would run for about 60 lakh revolutions.

So that's 24 lakh revolutions or 67% more than the car engine.

Let's say that the speed increases to 60 km/h. The engines would have to run for 16.67 hours. The difference between the car and the bike increases even more.

At 60 km/h the car engine might run at about 2000 rpm in 5th gear. So it needs to run about 20 lakh revolutions to cover 1000 km.

But the bike engine would have to run at about 4500 rpm in 5th gear. In this case the engine would have to revolve about 45 lakh revolutionsb to cover 1000 km.

The difference is now 25 lakh revolutions or 125% more than the car engine.

The bike engine has only 1 litre of oil but it has run more revolutions per kilometre. The car has 3 litres and also runs far fewer revolutions than the bike engine. The conclusion is simple.

Obviously this is a simplified calculation but it helps understand why the oil in a bike needs to be replaced at much shorter intervals than that in a car.

[balenoed_]

Originally Posted by Justin

whereas all 4 wheelers use fully synthetic oil.

Not entirely accurate. Semi synthetic too goes into 4 wheelers.

[abhi9044]

Although others have already mentioned about the Air Cooled vs Liquid cooled engine thing, I would like to add a significant point to this thread.

The Oil Filter. We know that the oil in a bike has to protect gears, engine and as well as the clutch. We also know that a clutch wears eventually with time. So those organic microscopic particles are suspended in your engine oils. Also the gears, wear out and so do the engine parts. All the little particles are there in your engine oil.

But how can they harm your Engine? Most of the commuter motorcycles/scooters have a oil strainer that looks like this:



Whereas a car's oil filter element looks like this:-



We can see a car's oil filter can filter out much more smaller particles than compared to the motorcycle's/scooter's oil strainer. Thus helping in improving the oil drain intervals when compared to bikes.
Although nowadays many bikes come with a paper element oil filters(Just look at the new range of commuter bikes from Hero,Bajaj,Honda in 100-125cc segment) and I assume they should be able to allow their users to extend the drain interval.

Also the manufacturer's themselves admit that it is one of the herculean task's to develop a motorcycle oil when compared to a car engine's oil because it has to take care of the clutch slippage, the gears and the engine as well.

[Justin]

Originally Posted by balenoed_

Not entirely accurate. Semi synthetic too goes into 4 wheelers.

Didn't consider those as the engine oil change interval recommended for those is around 5000km mostly which is half the mileage mentioned in the title. Please correct me if I am wrong.