Choosing The Right Engine Oil

[Viru]

Please don't merge this with another thread, as this is the only thread just to explain the basics of choosing the right engine oil to keep our beloved vehicles running forever (metaphorically)!

(If you guys like it maybe we should park it for other users' reference purposes)

Disclaimer: I have NO endorsement with any company, neither do I have a personal interest/ulterior motive behind this article!

Synthetic or Mineral?
Unfortunately, it is not that simple.

The basic difference is that mineral oils are extracted from crude oil stock by men in greasy overalls while synthetic oils are manufactured in labs by men in neat white coats!

But the way to actually judge an oil is not by it's origin, but by the seemingly boring aspects we typically overlook.

Viscosity
Viscosity is the thickness of the oil.

This is always mentioned on the oil bottle, typically in the format "20W-50" or something similar for multi-grade oils. The number before the W (20 in this case) is the 'Winter' (Cold) viscosity, which is the thickness of the oil in a cold engine ie. at room temperature whereas the number after it (50 in this case) represents the 'Hot' viscosity at 98.9 Celsius ie. Engine operating temperature.
A higher viscosity number means the oil will be thicker. Viscosity of oil is rated at two temperatures because an oil is required to be thinner when the engine is cold, to allow easy starting, especially in very cold weather. But it must get thicker as the engine warms up to reduce wear and prevent component damage.
It is said that a lower viscosity will improve vehicle performance to some extent, as it provides less resistance to the movement of engine parts, and may even lead to a slight increase in fuel efficiency. Although this has never been properly proven, it has been reported, and I have experienced this before, although it was minor.
However, for long distance highway driving ie. above 130kph, you should never use a hot viscosity of below 30.
Synthetic oils were originally developed to allow lower viscosity oils that wouldn't freeze at extremely low temperatures.

Oil additives
This refers to the non-lubricant chemicals in the oil.

These additives are the main component that set oils apart. They include corrosion inhibitors, viscosity modifiers (that allow oil to change viscosity with temp.), detergents and other compounds to help reduce friction and increase engine life. The main advantage of synthetics for the average user lies here, as Synthetic oils are compatible with a much better range of detergents and friction reducers, allowing us to replace the oil less often, increase engine life and economy, etc. Although manufacturer's precise list of additives are top-secret, they let us know the benefits of them. For example Castrol Magnatec contains magnetised particles that cling to the engine parts even when the engine is off and oil is not circulating and Castrol GTX (Mineral) has a heavy-duty detergent to prevent the buildup of sludge in the engine. Additives contribute to most of the cost of an oil, which is why good oils tend to be much more expensive, despite seeming identical on paper!

Friction rating
This determines how good of a lubricant an oil is.

Contrary to popular belief, this is not interrelated with viscosity. It determines the amount of resistance an oil poses to movement when it is trapped between two moving components such as the Piston and Cylinder Wall.
It is rated by the American Petroleum Institute (API) on an alphabetical scale:

For petrol: SA onwards (S for Standard cycle), where a higher alphabet is better. ie. SN is better than SG.
For diesel: CA onwards (C for Compression cycle), where a higher alphabet is better. ie. CF is better than CB.

Thanks to modern technology, higher rated oils help reduce engine noise, vibration, harshness and wear. So prioritize this while choosing between oils of the desired viscosity.

How often to change your oil
Changing too often can be as bad as changing too infrequently!

This is because the ability of some additives to function and make a difference actually increases with usage. So if you have invested in a good oil, do not be in a hurry to replace it, every 6000km for Mineral and 10000km for Synthetic is plenty for cars in Indian conditions! However, subtract 2000km from this is you do offroading or farm driving with a stock air filter.

Just make sure you change the oil filter everytime, or it will be a wasted exercise!

Miscellaneous

Purely synthetic oils are only used in racing or -50Celsius applications, as they are infeasible otherwise.

Most oils advertised as synthetic are actually a blend of Synthetic and Mineral oils, to get a good balance of the advantages of both!

Make sure you check the size of the oil sump of your car (from the manual/internet) before you buy the oil!

Now that you've confused us, how should we choose?
Well, it comes down to preferences.

If you like more responsiveness and typically stick to city roads, try a lower viscosity, but for India never go below 5W-30.
For highway driving at speeds above 130kph never go below 5W-40.

Feel free to experiment! Almost all of the oils in the market, whether synthetic or mineral, are compatible with one another. So you can change oils without needing an engine flush until you find the perfect one. If you are feeling very adventurous, you may even decide to mix (AT YOUR OWN RISK) two or more oils to get some advantages of both.

If your car is more than 10 years old, do not go below 10W-40, because the clearances with the engine would have become slightly larger due to wear and a thin oil may seep in some rare cases.

It is always great to check the recommended oil grade or friction level in your vehicle manual to know where to start your search, you could also contact an oil manufacturer such as Shell and ask if an oil you like would be suitable, as their staff is usually quite competent.

The normal oil that most service stations in India use is Mineral oil rated at API SG and 20W-40 viscosity because it is the cheapest option for them, especially in bulk. It's not actually too bad, but a good quality oil will easily make up for the price difference in the long term.

Changing the oil on a car is something that any amateur can do, but most service stations will not ask questions or charge extra if you tell them to put your own oil in during a service, you can always threaten them if they argue though.


Feel free to ask me questions or tell me if I missed anything!

 

[mukeshus]

Viru: Thanks for sharing the info in detail.

I could understand many things in this post.

Even i was in dilemma, about the engine oil i have to go for.

All these 5 years i have sticked with company recommended one.

This time thinking to go for Shell HX6 15W40.

Is Mobil Delvac still available or discontinued?

 

[Releesh]

viru@

first question from my end.

i was going to start a thread to get the suggestion form you all.

my 2006 esteem crossed 4.8 k km (60% city & 40 %highway most of the time 3-5 people with A/c)and 6 months after last oil change(Servo 20W40). usually i change oil once in a year or after 5K km though as per service manual it is 10K km. i had to go for a long trip next week end(1200km total).
I would like to change to a better oil (better grade, semi or synthetic oil), if it will increase the engine smoothness and low end torque(little bit?). please suggest. My car odo is at 66800 now.

 

[Viru]

Viru: Thanks for sharing the info in detail.

I could understand many things in this post.

Even i was in dilemma, about the engine oil i have to go for.

All these 5 years i have sticked with company recommended one.

This time thinking to go for Shell HX6 15W40.

Is Mobil Delvac still available or discontinued?

You're welcome!

To be honest, I am not 100% sure, but as far as I have experienced, Mobil oils are becoming increasingly difficult to find!
Last month I spent many hours in the market looking but could only find some guy trying to defraud me by selling used oil in a Mobil bottle! Luckily I spotted the open seal and looked inside the bottle!

viru@

first question from my end.

i was going to start a thread to get the suggestion form you all.

my 2006 esteem crossed 4.8 k km (60% city & 40 %highway most of the time 3-5 people with A/c)and 6 months after last oil change(Servo 20W40). usually i change oil once in a year or after 5K km though as per service manual it is 10K km. i had to go for a long trip next week end(1200km total).
I would like to change to a better oil (better grade, semi or synthetic oil), if it will increase the engine smoothness and low end torque(little bit?). please suggest. My car odo is at 66800 now.

Servo 20W40 is Mineral Oil with very few additives. As your car is slightly old, drives mainly on highways and you want some more low-end torque I would suggest going with a 5W30 or 10W30 oil with at least an API SG rating. I have found Castrol Magnatec 5W30 to be great in personal experience, and it has good detergents too (This is a part-synthetic oil), and as a matter of fact I tested it in another esteem!

But I think 5K is too soon to be changing the oil, especially on Highway conditions! If you buy a good part-synthetic you shouldn't have to change it for at least 10K, but for mental assurance you can check the thickness and colour of the oil when it is new, then monitor it over time. At 10K the colour would have changed, but you will observe that it's lubricating properties are unaltered, so it's still not an urgent replacement.

If you find particulates or sludge in the oil after 5K (Check for a thick layer of sludge by shining a light down the oil filler hole), get your fuel and air filters checked.

 

[alexddas]

viru@

first question from my end.

i was going to start a thread to get the suggestion form you all.

my 2006 esteem crossed 4.8 k km (60% city & 40 %highway most of the time 3-5 people with A/c)and 6 months after last oil change(Servo 20W40). usually i change oil once in a year or after 5K km though as per service manual it is 10K km. i had to go for a long trip next week end(1200km total).
I would like to change to a better oil (better grade, semi or synthetic oil), if it will increase the engine smoothness and low end torque(little bit?). please suggest. My car odo is at 66800 now.

Your interval on changing on kms is good but in days its good you change every 6 months.
If you are changing every 5000kms then you do not need a synthetic oil.

 

[Viru]

Your interval on changing on kms is good but in days its good you change every 6 months.
If you are changing every 5000kms then you do not need a synthetic oil.

Using time as a scale for maintenance checks is an utter waste of time and money, and I can simplify the reason for you: Cars are NOT like sodas, they do not expire when unused!

This applies more than anything else to engine oils, which are designed to retain their chemical configuration despite the punishment they take whether in an engine or on a shelf.

Do NOT use frequent oil changes as an excuse to buy cheap oil! You will be much better off buying an expensive oil and letting it run for 10,000 Kms, simply because these contain some additives that are absent in cheap oils. These additives cover a wide range of functions and prolong the life of the engine, while giving many day-to-day running benefits such as fuel economy.


This is the benefit of Synthetic oil. Not only does it allow longer oil change intervals, but it is an effective solvent for more detergents/corrosion inhibitors/friction reducers, etc. making it a much healthier option for the car!

 

[alexddas]

Toyota still uses semi synthetic oil and recommend to change every 10000kms
They do not recommend fully synthetic.
Its because its not necessary for the engine.

If you change every 5000kms it is the better thing you can do to the engine.
This prevents excess carbon deposits.

 

[alexddas]

Changing oil every 5000kms reduces carbon build up and deposits.
In every oil change the engine gets flushed.
If there is less carbon build up or deposit on engine we do not need a synthetic oil or a chemical flush.
So you do not need to change to a synthetic oil if you are changing oil in 5000kms interval.
Even HONDA TOYOTA runs on semi synthetic.

 

[Viru]

Toyota still uses semi synthetic oil and recommend to change every 10000kms
They do not recommend fully synthetic.
Its because its not necessary for the engine.

If you change every 5000kms it is the better thing you can do to the engine.
This prevents excess carbon deposits.

As previously mentioned, there is no fully synthetic oil commercially available for passenger cars. Products which are labeled as "Fully synthetic" are actually ~80% synthetic.

Purely synthetic oils are only used for Racing and extremely cold climates.

Changing good quality blended oil every 5,000km is not only a waste of money, but worse for the engine in the long run, for reasons previously mentioned.

Changing oil every 5000kms reduces carbon build up and deposits.
In every oil change the engine gets flushed.
If there is less carbon build up or deposit on engine we do not need a synthetic oil or a chemical flush.
So you do not need to change to a synthetic oil if you are changing oil in 5000kms interval.
Even HONDA TOYOTA runs on semi synthetic.

Unnecessarily frequent oil changes are a very rudimentary method of reducing Carbon buildup that only applies to people who would rather buy horrible quality oil and waste all of their time in a garage.

The huge development in engine oil technology (Yes there is such a thing) over the years means that oils are capable of flushing away most of the harmful deposits on the engine (Not just Carbon ones) if used for an ideal interval (not too long, not too short). These particulates are then caught by the oil filter.

It is impossible to accurately determine the accumulation of carbon on an engine, so why risk it by using cheap oils?

USING A BETTER OIL WILL SAVE YOU MONEY IN THE LONG TERM on fuel, maintenance, and everything else.

FYI when I say "synthetic" I am referring to any blend of synthetic and mineral oil. Purely synthetic oils are NOT available in the passenger vehicle market.

 

[alexddas]

Semi synthetic oils available in the market are not cheap in quality.
And an oil change at 5000kms do not do any worse to your engine and these changes flushes the engine as well and this type of flushing is good for the engine.
Very few car makers promote synthetic, the promotion comes from the oil manufactures only.

 

[Viru]

Read a post carefully before you try and refute it:

I never said all semi-synthetics are cheap quality, I was referring to any cheap quality oil in general. But nobody can disagree that there are low quality semi-synthetics also present in the market.

If you would have bothered to read the original post before trying to outsmart everyone, you would have spotted the explanation behind the statement that frequent oil changes can be harmful. This isn't the first time I have had to spoon-feed you:

"Changing too often can be as bad as changing too infrequently!

This is because the ability of some additives to function and make a difference actually increases with usage. So if you have invested in a good oil, do not be in a hurry to replace it, every 6000km for Mineral and 10000km for Synthetic is plenty for cars in Indian conditions! However, subtract 2000km from this is you do offroading or farm driving with a stock air filter."

The reason behind this is pretty complicated chemistry, if you want to discuss this start a separate thread instead of cluttering this one.

You seem to be obsessed with flushing! The reason behind this must be that you are ignoring the presence of detergents in engine oils and also ignoring the pressure and speed with which oil circulates within an engine.

This is not a matter of marketing, I am not affiliated with any oil manufacturers. Maybe you should read the article, you will learn some things that will help you make more accurate statements in the future. (No offense)

 

[alexddas]

Read a post carefully before you try and refute it:

I never said all semi-synthetics are cheap quality, I was referring to any cheap quality oil in general. But nobody can disagree that there are low quality semi-synthetics also present in the market.

If you would have bothered to read the original post before trying to outsmart everyone, you would have spotted the explanation behind the statement that frequent oil changes can be harmful. This isn't the first time I have had to spoon-feed you:

"Changing too often can be as bad as changing too infrequently!

This is because the ability of some additives to function and make a difference actually increases with usage. So if you have invested in a good oil, do not be in a hurry to replace it, every 6000km for Mineral and 10000km for Synthetic is plenty for cars in Indian conditions! However, subtract 2000km from this is you do offroading or farm driving with a stock air filter."

The reason behind this is pretty complicated chemistry, if you want to discuss this start a separate thread instead of cluttering this one.

You seem to be obsessed with flushing! The reason behind this must be that you are ignoring the presence of detergents in engine oils and also ignoring the pressure and speed with which oil circulates within an engine.

This is not a matter of marketing, I am not affiliated with any oil manufacturers. Maybe you should read the article, you will learn some things that will help you make more accurate statements in the future. (No offense)

This is because the ability of some additives to function and make a difference actually increases with usage.

Kindly post a link or source.
Or kindly clear it if its your other so called investigation,

Guys its just commonsense that changing oil at an interval of 5000kms will not harm an engine,hope i do not want a source or link on it as every one knows it.
@mods
Hope i am discussing on the topic.

 

[alexddas]

All my cars use semi synthetic oil and changed every 5000 to 6000kms and filter at 10000kms.
Swift 215000kms odo
ritz 110000kms
Innova 4.5Lkms
All run these kms only on just oil change, work done is change of timing chain/belt.
I use synthetic and changes in 10000kms on punto as the car comes on synthetic.
I never flushed either of the above engines.
That is my experience shared.
so i think our engine do not need a synthetic which is available in the market if the oil is changed at this interval.
Most of you guys run 5000kms in 6 months.
The car makers recommend to change oil at every 6 months so why you people go for synthetic.
workout on it.

 

[Viru]

All my cars use semi synthetic oil and changed every 5000 to 6000kms and filter at 10000kms.
Swift 215000kms odo
ritz 110000kms
Innova 4.5Lkms
All run these kms only on just oil change, work done is change of timing chain/belt.
I use synthetic and changes in 10000kms on punto as the car comes on synthetic.
I never flushed either of the above engines.
That is my experience shared.
so i think our engine do not need a synthetic which is available in the market if the oil is changed at this interval.
Most of you guys run 5000kms in 6 months.
The car makers recommend to change oil at every 6 months so why you people go for synthetic.
workout on it.

1. You fail to understand that the main difference between "Semi-synthetic" and "Synthetic" is purely MARKETING.
2. If you're changing your synthetic every 5,000Km you're WASTING your own money AND the planet's resources. The former is not really my problem.
3. If you change your oil without changing the filter every time it is an utterly wasted exercise, and will be worse for the engine.
4. No engine needs flushing, even if you decide to stretch intervals waayy past the recommended, that's the beauty of modern technology.
5. Time is the WORST way to measure oil change intervals. Run on distance and usage (eg. Rev range) factors to keep your engine and wallet healthy simultaneously. I repeat: OIL DOES NOT EXPIRE.
6. As said before, frequent oil changes are NOT an excuse for cheap oil, it is actually the other way around. Buy a high quality oil to decrease running costs, decrease NVH, increase engine life and you can use it for longer without changing it, saving maintenance costs too!

Please don't try and sabotage the cars of people on this forum simply because you are trying to win an argument even though you don't know what you're talking about.

 

[alexddas]

The point is our modern tech engines do not need special additives and detergents which are in synthetic
The semi synthetic oil which most of the car makers recommend is enough.
And as per my experience a semi synthetic oil changed at 5000-6000kms is good for the engines as all my cars crossed these much kms only because of this practice.
People in forum experience shared.
The posts remember me of the booklets which comes with some oil companies which they use to promote their product.
Do not fall on it use good semi synthetic recommended and if you people think my experience have anything to do with you then change on 5000-6000kms.
Viru you continue, i am done.