[hserus]

Originally Posted by Sridhar K

Your views please on my query about 10K oil change interval for Mahindra engines using Maximile Feo, a mineral oil and other choices for XUV300 which requires a 15W40 CH4 at a minimum?

Search back over many posts here. 10K / 1 year whichever is earlier oil changes are perfectly fine for Feo

Or feel free to use any mineral or synthetic diesel oil that's CH4 or greater (mineral - Shell Rimula R4, Synthetic - Mobil Delvac 1 or Amsoil 5w40 Turbo Truck).

[Spark]

Hi,
if I may interrupt, would it be wise to use 5w40 on a Hyundai i10 Grand PETROL?
Specs recommend 5w30, but would a slightly thicker Oil do any harm to the engine?
Delhi's excessive heat and continuous start-stop traffic must be putting extra load on the parts, so may be a slightly healthier oil film might help reduce wear 'n tear.
This is also from the perspective that I am contemplating switching to CNG in some time, which could further hasten the oil degradation.

While diesel and petrol Oils are inherently different in their composition, could the extra cleaning additives of the Mobil 1 5w40 harm seals in the petrol engine?

Looking forward to expert comments/suggestions/ridicule (But strictly expert please ;-) ).

Regards

[hserus]

Any A3/B4 should work - so get a 5w40 A3/B4 like Shell Helix Ultra if you like. Though the HX8 Shell 5w30 works just fine on my wife's i10 in Madras summers so don't overthink it.

There isnt' very much difference between the two compared to a really low viscosity oil like 0w20 / 0w40 that Hondas use.

Originally Posted by Spark

Hi,
if I may interrupt, would it be wise to use 5w40 on a Hyundai i10 Grand PETROL?
Specs recommend 5w30, but would a slightly thicker Oil do any harm to the engine?
Delhi's excessive heat and continuous start-stop traffic must be putting extra load on the parts, so may be a slightly healthier oil film might help reduce wear 'n tear.
This is also from the perspective that I am contemplating switching to CNG in some time, which could further hasten the oil degradation.

While diesel and petrol Oils are inherently different in their composition, could the extra cleaning additives of the Mobil 1 5w40 harm seals in the petrol engine?

Looking forward to expert comments/suggestions/ridicule (But strictly expert please ;-) ).

Regards

[Spark]

Originally Posted by hserus

Any A3/B4 should work - so get a 5w40 A3/B4 like Shell Helix Ultra if you like.

Many thanks for your response HSERUS!
Since you've been here on the form for long and must've seen it all - do we have feedback for 5W40 oil in a i10 Grand Petrol?


Regards

[Spark]

Multi-Grade motor oil are apparently supposed to run leaner @ cold temperatures while thicken as they acquire heat from the engine "0W40".
So base viscosity index at cold start is 0 while @100 degrees it should thicken to a higher viscosity index of "40" - in actual we see just the opposite - Cold Oil is much more thicker to start with and as it heats up, it looses its viscous properties to operate at a thinner Grade. So many videos @ Youtube can do the justice to this observation.

@ Oil experts: Is there more than what meets the eye?

Regards

[rdst_1]

Originally Posted by Spark

Multi-Grade motor oil are apparently supposed to run leaner @ cold temperatures while thicken as they acquire heat from the engine "0W40".
So base viscosity index at cold start is 0 while @100 degrees it should thicken to a higher viscosity index of "40" - in actual we see just the opposite - Cold Oil is much more thicker to start with and as it heats up, it looses its viscous properties to operate at a thinner Grade. So many videos @ Youtube can do the justice to this observation.

@ Oil experts: Is there more than what meets the eye?

Regards

Oil weight is a term used to describe the viscosity of an oil, which means how well it flows at a 'specific temperature' . The Society of Automotive Engineers (SAE) assigns a viscosity number, or weight, to oil based on its flow at 210 degrees F, which is roughly the standard operating temperature for most motors. The higher the number, the thicker or slower flowing it is.

A 0 weight oil will definitely be thinner than a 40W oil at 210 degrees F. However when you are observing the oil it is not at 210 degrees F at the moment of cold start. By the time temperature reaches 210 F, the multi grade oil has changed into a 40W oil. To actually see the difference, you will have to find a single grade oil and then compare them at the same temperature. You will definitely find a 0 weight oil to be thinner than a 40 weight oil when they are at the same temperature.

[anandhsub]

Viscosity index measures rate of change of viscosity with temperature. All liquids become less viscous at higher temperature but lower the index more sensitive they are. Engine oils have viscosity modifier additives which make the oil have a low index at low temperatures to allow easier flow on a cold start and high index at higher temperatures to allow the oil to retain lubrication. Hence the 40 number doesn't mean it becomes more thick but just that it becomes less thick more gradually.

[Spark]

Originally Posted by rdst_1

A 0 weight oil will definitely be thinner than a 40W oil at 210 degrees F.

Thanks for clarifying this distinction of measuring viscosity of Grade @ 210F degrees, which implies that the two viscosities are to be measured @ different temperatures to bring out the "relative" difference.

@32 degrees: 0W oil would be thinner than 5W.
@210 degrees: 30W oil would be thinner than 40W.

Lesser the "W" rating, thinner the oil under its respective temperature slab.
Which means under no circumstances - the same oil would be thicker when heated? Right?

However next statement is not so clear:

Originally Posted by rdst_1

By the time temperature reaches 210 F, the multi grade oil has changed into a 40W oil.

Which is trying to subdue inference drawn by the first statement. However I think you mean to specify that when comparing viscosity of the same oil under different temperatures, it would "relatively" act differently @ that temperature range than doing so in absolute terms.

I might have missed it, but in general discussions this phenomenon of Oil thinning with increase in temperature is understated, which steers people like me into thinking that probably Multi-Grade motor oils thicken in absolute terms when they heat up.

But thanks for the inputs, hope it helps others- unless it was imperatively obvious!

[rdst_1]

You are still getting confused but it is ok.
When comparing viscosities, the temperature can never be different. It has to have the same temperature. Please try and find single grade oils of different weights. Let's say you procure one oil of 10 weight and one of 40 weight. At room temperature you will be able to see that the 10 oil is thinner and flows more easily than the 40 oil.
The SAE body chose an arbritary value of 210F to conduct their test at and made an index which assigns these values of 10 and 40 to the oils.
When it comes to multi-grade oils, the same oil acts as 10 oil at lower temperature and 40 oil at higher temperature. This temperature has nothing to do with the comparison of the oil. This is a characteristic that was needed so that we don't damage the engine.

Originally Posted by Spark

Which is trying to subdue inference drawn by the first statement. However I think you mean to specify that when comparing viscosity of the same oil under different temperatures, it would "relatively" act differently @ that temperature range than doing so in absolute terms.

This is only true for multi grade oils and this was the exact reason that multi grade oils were invented. For a single grade oil, it will continue having the same character under different temperatures when compared to other single grade oils.

Please note that I am using the word 'character' and not 'viscosity'. Viscosity always changes with change in temperature and hence we use the Viscosity Index to specify oils and not the absolute Viscosity values.
If you can search on google and find the graphs of viscosity wrt temperature for oils of different weights, it will become much more clear to you what I am trying to say.
Just assume that a 10 weight oil has viscosity of 3 at 30 degrees and 1 at 100 degrees. A 40 weight oil viscosity will always be more so let's assume it has a viscosity of 10 at 30 degrees and 7 at 100 degrees.
So now a multi grade oil 10W30 will have viscosity of 3 at 30 degrees(cold start) but a viscosity of 7 at 100 degrees (operating temperature of engine).
I hope this example can clear some of the doubts.

[Spark]

Yes, with things stated explicitly over last few comments - its now put in a better perspective.

Regards

[Spark]

In other words for Grade 5W40 : it would only get as thin as a 40, instead of 5.


Mods: Request to merge it with the previous comment. Edit timed out. Thanks

[Sandeep500]

Hi, I serviced my Jeep Compass about 2 months back and engine oil was changed along with other things as per manual. Today morning after a drive of about 80 Kms the msg was displayed that oil change required. This was only after about 4000 Kms the vehicle being driven. The service interval is 15000 km or 1 year. I checked the oil , it seems fine as there is no significant discoloration. Then I talked to service advisor , he said not to worry as he has seen or heard complaints from customers even after few days of vehicles being serviced , so drive as usual. It is pertinent to mention that I topped about 300 ml with same grade of oil 5w30 after few days of service. Please advice if I need to change oil or carry on as told by service advisor of dealership. The service interval displayed is 300 days or 10500 km.

[Spark]

Originally Posted by Sandeep500

Hi, I serviced my Jeep Compass about 2 months back and engine oil was changed along with other things as per manual. Today morning after a drive of about 80 Kms the msg was displayed that oil change required. This was only after about 4000 Kms the vehicle being driven. The service interval is 15000 km or 1 year. I checked the oil , it seems fine as there is no significant discoloration. Then I talked to service advisor , he said not to worry as he has seen or heard complaints from customers even after few days of vehicles being serviced , so drive as usual. It is pertinent to mention that I topped about 300 ml with same grade of oil 5w30 after few days of service. Please advice if I need to change oil or carry on as told by service advisor of dealership. The service interval displayed is 300 days or 10500 km.

Looks like a false alarm.
Oil drain is a function of Service Interval or unexpected Oil Contamination/degradation.
Neither of the two seems like the case with you.

In-Built alert system would have a very rudimentary way to assess Oil quality if at all.
In most probability it's base-lined on Oil drain sensor reading + Odometer reading + Date.
Add in a preset Kms on the Odo. / Months on the baseline date and system's algorithm should trigger Oil change alert.
(In your case, looks like it's 15000km/ 1 Year).

Most probably a software glitch, tapping into un-handled exceptions

Inspection of Oil level on Dipstick along with check for unusual de-coloration/ rough to touch texture should suffice. So probably SA is suggesting in the right direction.

[Sandeep500]

Thanks,Spark for your reply. I think you may be right as now I can remember that I have changed engine oil about 2000 to 2500 Kms earlier then required based on 1 year coming earlier then required number of kilometers , so may be that can be the reason.

[rdst_1]

Originally Posted by Spark

In other words for Grade 5W40 : it would only get as thin as a 40, instead of 5.


Mods: Request to merge it with the previous comment. Edit timed out. Thanks

Bingo.
Glad I could get the point across as I consider myself to be a very bad and impatient teacher.