[akshay4587]

Originally Posted by PatienceWins

Is anyone using Synthetic oil for Getz Petrol? If so, which one?

My Getz 1.3 has covered 62000 kms and thinking about switching to synthetic in next service. Shell is easily available in shell petrol pumps, so that seems to be a convenient option.

During my Accent ownership days;i used Mobil 1 5W50 for mine.
And engine was literally new after 1.35L kms.
I would recommend that you go with Mobil 1 0w40 or 5W50(hard to find);choice is yours.

[ramzsys]

Originally Posted by a4anurag

Can you explain why in detail if you don't mind?!

Thanks,

Anurag.

The obvious reasoning is that for a given rpm count, you cover much more distance in the highway than in the city.

Coolant temperature can be taken as a reference for engine oil temperature and oil remains cooler at highway speeds than in the city.

e.g For the 1.4 tdci engine in ford, i have seen 82-83C at highway speeds and 90+ at city drives.

Engine wear/engine oil wear happens most at the cold starts and the time till it is warmed up- this cycle is higher in city running than in highway running(per '000s of km covered).

[saket77]

Originally Posted by Jeroen

It would be interesting to know what/which component in a lub oil breaks down due to heat? Are you suggesting that your lub oil gets hotter on a motorway run than in city traffic? Again, I don't think so, its not logical.

Truth is that city type of driving is far more detrimental on the engine wear and tear and on the quality of the lub oil then highway runs.

Jeroen

Agree with you that city driving is more detrimental on car's engine and the engine health of a car that has done more of highway miles will be better as compared to same number of miles put under city driving.

But under highway conditions the engine will be running constantly at higher RPMs which means that the oil will be constantly at a higher pressure. This in turn will lubricate the moving parts better, but that also means more work for the oil. In process, it will also be flowing away more heat generated by the engine.

In the city driving, the cold start-ups, the oil faces more challenge of contamination due to moisture build up on the cylinder walls. This water ultimately mixes with the oil and hence it degrades.

Highway runs on the other hand mean oxidation of oil at higher temperatures. Regarding the component of oil which is most vulnerable to heat are the additives, thereby reducing the viscosity of the oil making it poor at the task.

Now since you have the background and knowledge in the area, I would like to know your views on the matter too. In case, I am missing something, I would like to learn.

Originally Posted by ramzsys

Coolant temperature can be taken as a reference for engine oil temperature and oil remains cooler at highway speeds than in the city.

e.g For the 1.4 tdci engine in ford, i have seen 82-83C at highway speeds and 90+ at city drives.

Dear Ram,

You cannot take coolant temperature as engine oil temperature. Coolant temperature should not cross 90-95 deg. C. Also, anything over the boiling point of water, which is 100 deg. C, will never be able to 'cool' the engine. On the other hand, engine oil temperature crosses the 100 deg. C mark very often.

In my opinion, the more oil works for lubrication and for flowing the heat away from the engine generated by higher RPMs, more quickly it will degrade in higher temperature scenario. During cold start-ups, oil contamination due to moisture build up (& finally degradation) should be something which should concern us.

Regards,
Saket

[bullrun87]

Originally Posted by saket77

You cannot take coolant temperature as engine oil temperature. Coolant temperature should not cross 90-95 deg. C. Also, anything over the boiling point of water, which is 100 deg. C, will never be able to 'cool' the engine. On the other hand, engine oil temperature crosses the 100 deg. C mark very often.

In my opinion, the more oil works for lubrication and for flowing the heat away from the engine generated by higher RPMs, more quickly it will degrade in higher temperature scenario. During cold start-ups, oil contamination due to moisture build up (& finally degradation) should be something which should concern us.

Regards,
Saket

I disagree, I think that lower coolant temperature would result in a lower engine oil temperaure. So if your temperature reading is lower during highway runs then your engine oil temperature should also be lower.

why would you say coolant above 100 deg C wont cool the engine at all? Water boils at 100 deg c at atmospheric pressure. Water pump increases the pressure in the coolant circuit to above atmospheric and correspondingly the boiling point also increases. So if lets say the coolant system pressure is 2 bar, the boiling point of water has been raised to about 120 deg C. Even if your coolant temperature has exceeded 100 deg C you shouldnt worry it is still a liquid and can provide heat transfer.

[sgiitk]

@bullrun87; Most radiators are pressurised to 0.9 bar. Used to be 0.4 in the days of the Amby!

[saket77]

Originally Posted by bullrun87

I disagree, I think that lower coolant temperature would result in a lower engine oil temperaure. So if your temperature reading is lower during highway runs then your engine oil temperature should also be lower.

Apologies if that created a confusion, I should have written in a more clear manner. Just wanted to convey is that coolant temperature is not the engine temperature.

Originally Posted by bullrun87

why would you say coolant above 100 deg C wont cool the engine at all? Water boils at 100 deg c at atmospheric pressure. Water pump increases the pressure in the coolant circuit to above atmospheric and correspondingly the boiling point also increases. So if lets say the coolant system pressure is 2 bar, the boiling point of water has been raised to about 120 deg C. Even if your coolant temperature has exceeded 100 deg C you shouldnt worry it is still a liquid and can provide heat transfer.

Yes, though not sure of the temperature, but pressurized water in the system and the mixed coolant increase the boiling point of water. Thanks for correcting me. I was thinking too much on theoretical lines and considered only the boiling point of water.

Thanks,
Saket

[Jeroen]

Originally Posted by saket77

But under highway conditions the engine will be running constantly at higher RPMs which means that the oil will be constantly at a higher pressure. This in turn will lubricate the moving parts better, but that also means more work for the oil. In process, it will also be flowing away more heat generated by the engine.

In the city driving, the cold start-ups, the oil faces more challenge of contamination due to moisture build up on the cylinder walls. This water ultimately mixes with the oil and hence it degrades.

Highway runs on the other hand mean oxidation of oil at higher temperatures. Regarding the component of oil which is most vulnerable to heat are the additives, thereby reducing the viscosity of the oil making it poor at the task.

Higher RPM does not give a higher pressure perse. If you have a car that has an oil pressure meter you will see that the highest oil pressure you will see is when the oil is still cold. With the engine idling the oil pressure is often relatively low, but as soon as you rev up it will pick up and will stay at a certain value irrespective of how hard you rev the engine. It's essentially a very simple pressure controlled valve that keeps the oil pressure within a certain bandwidth of pressure.

There is a general and persistent misconception that engines don't do well when you run them for prolonged periods of time at high power output. Although it does vary from engine to engine, but certainly car engines can be run at high loadings for near infinite times. Under those conditions the engine tend to run very efficient at least from a wear and tear point of view. That includes and goes for quality of the oil as well.

There are several major factors that have an impact on the oil quality. One is how much exhaust gas gets blown past the piston (rings)? Obviously, engine health is a factor here, but even on a brand new engine there is some blow past. The problem as far as the oil is concerned is the various particles. The oil and its additives catch those particles and keep them fluid. Another, lesser know, but just as relevant is the state/cleanliness of intake air to start with. A lot of the particles in their can end up in the oil as well, in combination with the exhaust products.

I've said it before and I will say it again; it is far more important to change your filter then your oil. Because when the filter stops filtering the oil has to do all the work and it can only "absorb" so much. Car forum after car forum gets filled with endless garbage about oil changes, oil properties, synthetic vs mineral oil. Forget about it, Get the cheapest oil you can and replace your oil and air filter regularly. Its cheaper and very effective.

Coming back to topic, again under city conditions the engine and the oil have a far more harsh living then under a good more or less consistent highway driving. The biggest problem for an engine from a lubrication point of view is it not being hot/warm enough. That's when metal particle start to come off and end up in the oil and stay in that oil, unless you change your filters regularly!

I have done a write up on my experience with some oil research on marring diesels somewhere on this forum. Cant remember where, but if you manage to find it, you will find some more details there.

Jeroen

[sagarpadaki]

I completely agree with you Jeroen on the importance of changing Oil filter than the oil. Modern synthetic oils can run for 15K kms easily but the oil filter cannot filter effectively for that long.The chain is as strong as its weakest link. Hence the manufacturers ask to change the oil filter and oil because they obviously want to fill their coffers.

This time i have done the same. I decided to use the Mobil Delvac 1 which is a fully synthetic diesel oil for 15K kms including harsh city traffic. But got the oil filter changed at 8K kms. Earlier i used to change the synthetic oil at 10K kms by reading all the rubbish on many forums like you said and in process wasting a good oil and harming the environment. Now doing my bit to utilize the oil fully and also protect the environment.

This info and knowledge needs to be spread more .Until then people will do pre-mature oil changes and get a feel good factor thats all

[R2D2]

Originally Posted by sagarpadaki

Earlier i used to change the synthetic oil at 10K kms by reading all the rubbish on many forums like you said and in process wasting a good oil and harming the environment.

Need to disagree here. Most car enthusiasts change engine oil and filter according to manufacturer specified intervals. They have a time/KM change specification. Drain intervals so specified apply to both synthetic and mineral unless explicitly mentioned otherwise by the manufacturer, who obviously knows the engine best. Everything else is hearsay and as you put it so eloquently "rubbish"

As Jeroen says below, the ONLY way to gauge used oil is to do a lab test. The tendency to rub a drop of oil between the fingers to ascertain its efficacy is as scientific as thumping a tyre's sidewall to gauge pressure.

Till one does a lab test the only thing to be done is follow the owners manual.

[sgiitk]

Originally Posted by sgiitk

@bullrun87; Most radiators are pressurised to 0.9 bar. Used to be 0.4 in the days of the Amby!

Antifreeze also increases the pressure. Though possibly the heat transfer is reduced.

[sagarpadaki]

Originally Posted by R2D2

Need to disagree here. Most car enthusiasts change engine oil and filter according to manufacturer specified intervals. They have a time/KM change specification. Drain intervals so specified apply to both synthetic and mineral unless explicitly mentioned otherwise by the manufacturer, who obviously knows the engine best. Everything else is hearsay and as you put it so eloquently "rubbish"

As Jeroen says below, the ONLY way to gauge used oil is to do a lab test. The tendency to rub a drop of oil between the fingers to ascertain its efficacy is as scientific as thumping a tyre's sidewall to gauge pressure.

Till one does a lab test the only thing to be done is follow the owners manual.

Yes. I agree with you. But what I am trying to convey is that it's the oil filter that gives up its filtering capacity earlier than the oil losing its viscosity. Obviously the manufacturer won't recommend to just change the oil filter for the point mentioned before.

To your other point of manufacturers recommend change intervals, consider the old i20 and the i gen i20 diesel. Both have same engine, use same oil, same oil filter but the former has drain interval of 5k while for the latter it is 10k. How do you explain this discrepancy? For me it only looks like the manufacturer was taking the customers for a ride with the old model. But with the competition specifying 10k or 15k intervals, Hyundai was also forced to change the interval. And this is with mineral oil

[R2D2]

Originally Posted by sagarpadaki

Yes. I agree with you. But what I am trying to convey is that it's the oil filter that gives up its filtering capacity earlier than the oil losing its viscosity. Obviously the manufacturer won't recommend to just change the oil filter for the point mentioned before.

I believe the OEM filter will last at least as long and even maybe a few thousand KMs more than what is specified by the manufacturer. These companies err on the side of caution given the reluctance of owners to change oils/filters at regular intervals. So, if a recommended interval is 10K kms, the filter and even oil may go to 12K or even 13K before sludge and filtration capacity reduces the efficiency of the lube system drastically. Believe it or not, I know people who change only the oil but not the filter, no kidding! Now go figure. It leaves me aghast but I keep mum.

To your other point of manufacturers recommend change intervals, consider the old i20 and the i gen i20 diesel. Both have same engine, use same oil, same oil filter but the former has drain interval of 5k while for the latter it is 10k. How do you explain this discrepancy? For me it only looks like the manufacturer was taking the customers for a ride with the old model. But with the competition specifying 10k or 15k intervals, Hyundai was also forced to change the interval. And this is with mineral oil

Sagar, honestly I really don't know. While I am 100% sure many of a car manufacturer's instructions are driven at least partially by commercial interests, there may have been minor tech changes made to the engine components (unpublished as companies are free to change specs as they deem fit) in order to facilitate longer drain intervals.

Don't get me wrong, I am happy to see 15K intervals, but I strongly believe that the filter AND oil should be changed together. Why introduce the possibility of a weak link i.e. either the old filter or the old oil in the lubrication chain when it's your engine that benefits? Just my thoughts.

Cheers!

[bullrun87]

Originally Posted by sgiitk

Antifreeze also increases the pressure. Though possibly the heat transfer is reduced.

I agree sir, coolant is denser than water so higher percentage of coolant will result in higher coolant system pressure but correspondingly the heat transfer ability of the system diminishes.

[Jeroen]

Originally Posted by bullrun87

I agree sir, coolant is denser than water so higher percentage of coolant will result in higher coolant system pressure but correspondingly the heat transfer ability of the system diminishes.

What is relevant as far as the pressure is the boiling point. Boiling point of the coolant additives is higher then water. More coolant brings up the cooling point of the mix. The pressure itself is a result of the expansion of the mix (coolant and water) and has nothing to do as such with the boiling point.

Heat transfer is depend (if everything else remains the same and or constant) on the specific heat capacity of the mix. (although the density does play a role in the formula as well)


Jeroen

[bullrun87]

Originally Posted by Jeroen

What is relevant as far as the pressure is the boiling point. Boiling point of the coolant additives is higher then water. More coolant brings up the cooling point of the mix. The pressure itself is a result of the expansion of the mix (coolant and water) and has nothing to do as such with the boiling point.

Heat transfer is depend (if everything else remains the same and or constant) on the specific heat capacity of the mix. (although the density does play a role in the formula as well)


Jeroen

I agree with most of what you have said, more coolant will bring up the boiling point of the coolant water mix. But the pressure has a profound effect on the boiling point of all known liquids. For example water boils at 100 deg C at atmospheric pressure but at a pressure of 1 bar above atmospheric it will boil at 120 deg C!!
So lets say if your running your car with water and temp in the coolant circuit is 105 deg C but all of the water in the circuit will still be liquid due to the higher pressure. but if you open the coolant nozzle at the top, steam will come out because the pressure is now atmospheric and water needs to be steam at 105deg C and atmospheric pressure. Similarly a coolant water mixture will also boil at higher temperatures if pressures are higher than atmospheric.