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Mo*il 10W-30 or 15W-40 Which suits for my 55k Mileage car?

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Hi,

Earlier I was used Mo*il 10W-30 for my Suzuki Swift(Japanese beetle). But this time service station changed that oil to 15W-40. Mileage is around 55k now. 

Now I feel, car ride is not smooth as earlier (Not sure this because of engine oil or some other reason). So what is the recommend engine oil grade for my car?

thanks

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A sensitive subject it is,..

 the viscosity change can not be directly linked to the rough running of the engine ,better get the ignition system checked as it is a prime suspect , due to possible water contamination of the electronics.

.

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Is it a rough idle you are experiencing?

 

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On 2/10/2018 at 9:14 AM, flashmark said:

Hi,

Earlier I was used Mo*il 10W-30 for my Suzuki Swift(Japanese beetle). But this time service station changed that oil to 15W-40. Mileage is around 55k now. 

Now I feel, car ride is not smooth as earlier (Not sure this because of engine oil or some other reason). So what is the recommend engine oil grade for my car?

thanks

The first  number (10W or 15W) has no meaning in tropical conditions. It is the cold start viscousity. But second number yes. Higher the number thicker the oil and vice versa.  Usually , higher the temperature, lower the viscousity (i.e. thinner the oil) . As engine heated up, viscousity drops. This high temperature viscousity matters the performance, fuel economy, etc.. In modern synthetic oils these viscosity variations in higher temperatures are better controlled.

In general, thicker the oil, better the protection for engine, but engine needs to work  more to overcome the resistance. It may also have an impact on your fuel pumping and filtering system as well.

If the oil is thinner it becomes more flowable and less resistance at higher temperature. For engines with higher mileage plus possible wear and tear may experience less fuel efficiency with thinner oils.  Also drop in the oil level. That is why people go for higher thickness oils.  

In your case better to use SAE 40.  

Additonally refer the manufactured date of the oil. Generally the shelf life of motor oil is 2 years. It will experience natural decomposition even during the storage. 

Always change the filters at every oil change.  I don't strictly go by the mileage for changing the oil. It depends on your driving habits, operating temperature of your engine, condition of your engine.

All these standards developed by the Society of Automotive Engineers 

SAE
Viscosity
Grade[°C]
Min. Viscosity
[mm²/s]
at 100 °C
Max. Viscosity
[mm²/s]
at 100 °C
High Shear Rate Viscosity
[mPa.s]
at 150 °C
0W 3.8 -- --
5W 3.8 -- --
10W 4.1 -- --
15W 5.6 -- --
20W 5.6 -- --
25W 9.3 -- --
20 5.6 <9.3 2.6
30 9.3 <12.5 2.9
40 12.5 <16.3 2.9 *
40 12.5 <16.3 3.7 **
50 16.3 <21.9 3.7
60 21.9 <26.1 3.7
 

* 0W-40, 5W-40 & 10W-40 grades
**  15W-40, 20W-40, 25W-40 & 40 grades

Image result for multigrade motor oil viscosity vs temp

Reference: http://www.viscopedia.com/viscosity-tables/substances/sae-viscosity-grades/

Edited by trish_auto
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15 hours ago, Rumesh88 said:

Is it a rough idle you are experiencing?

 

What does that mean?

What does that mean? What I'm  experiencing are as follows.

1. Engine running hard, Drive is not smooth and noisy than earlier 

2. Fuel efficiency drop

 

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10 hours ago, flashmark said:

What does that mean?

What does that mean? What I'm  experiencing are as follows.

1. Engine running hard, Drive is not smooth and noisy than earlier 

2. Fuel efficiency drop

 

When the engine is fully warmed up and running in idle mode (like when you stop at a traffic light on your way) if you notice an unusual engine vibration and an shaky RPM needle that is that we call a rough idle. 

 

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Just to add one more thing to your knowledge.  Two days back I had a visit to the head office of one of the leading engine oil brands in Sri Lanka.  I had a chat with the head of the sales about the shelf life and expiry date of the oils.  According to him most of the oils are marked with manufactured dates and it will stand its properties for a limited period  on shelf. This shelf life may vary and it can be up to 2-5 years.  After that period oil starts its decomposition process.  According to him, expired oils offer lower performances that of new oil.  In Sri Lanka, some dealers get the oils through various importers (not directly through the agents) thus enough room to play around with these printed manufactured dates. 

Be more concern on what you are paying for. 

Thanks :)

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On 2/25/2018 at 7:56 AM, trish_auto said:

I had a chat with the head of the sales about the shelf life and expiry date of the oils.  According to him most of the oils are marked with manufactured dates and it will stand its properties for a limited period  on shelf. This shelf life may vary and it can be up to 2-5 years. 

I just asked from the dealership and you are correct. The tech at the dealership told me Full synthetic oil can be in shelf for 5 years.

BTW, he was not a fan of Full synthetic oil. He said he prefer conventional oil and change in shorter intervals by him self (Oil + Filter).

 

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11 minutes ago, kmeeg said:

I just asked from the dealership and you are correct. The tech at the dealership told me Full synthetic oil can be in shelf for 5 years.

BTW, he was not a fan of Full synthetic oil. He said he prefer conventional oil and change in shorter intervals by him self (Oil + Filter).

 

Agreed. I also used to do it. But modern full synthetic oils can perform higher mileages without a significant loss in their properties compared to conventional oils.  Specially for b/n or very low mileage, it is recommended to go for thinner oils , difficult to find conventional oils in that viscosity range. 

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