[nitrous]

I've learnt somewhere that xW40 starts losing efficiency at around 35 degree centigrade.
This isn't ideal for our summers.But, we've been using 10W40,15W40,20W40 oils for aeons now and not experienced any issues.
@Sankar:I've been eyeing this 15W50 Shell Helix ultra for my summer oil change. The old price was Rs.2400 for 4 litres.

[Sankar]

That is a very good price Nitrous it's almost in the Motul 300V range.

I tried in vain for the Shell Helix Ultra15W50 here in Tvm and ended up buying Mobil1. Sticker price was more for the 5W50 than for the 5W40. Had to pay 900/l for 5W50 and 700 for 5W40. Both synthetics.

[gemithomas]

thanks a lot for all suggestions. Please let me know if my understanding is right.

A 5W50 grade oil behaves like a 5 grade oil when cold and like a 50 grade oil when hot. Thats why they are called multi grade oils and they are used in vehicles because the single grade oils would not be able to cope with the extreame variations in temperature qhen the engine is cold and hot. These grades are given based on how they flow at the given temperatures. This is also based on how viscous it becomes at different temperatures. A '5' grade is less visous and means that the oil will take less time to flow through a small opening(in layman terms) and a 50 grade oil will take more time.

If the above theory stands true. DOnt you guys think that using a 5W40 oil would be better than using a 5W50 oil if the recommended grade is 15W40.

To make things easier dont you think that its not bad to go down with the first W number if you are willing to top up the oil at earlier intervals than with teh recommended grade (because the lower visousity leads to more oil loss in use) But moving above in the higher w value would mean that the oil takes more time to move around.

Sorry for the long post. This is just confusing me to the core.

[shuvc]

Originally Posted by gemithomas

To make things easier dont you think that its not bad to go down with the first W number if you are willing to top up the oil at earlier intervals than with teh recommended grade (because the lower visousity leads to more oil loss in use) But moving above in the higher w value would mean that the oil takes more time to move around.

@gemit, I don't understand oils much. However extending your 'laymans' discussion, I'll try to think aloud a bit.

A 5W oil may be less viscous than a 15W oil, but AFAIK that would be at the temperature unit of 5. Viscosity of a 5W oil should be similar to that of a 15W oil, when the temperature unit is 15.

Now the operating temperature of the oil is dependent on the engine temperature? Actual oil temperature should have nothing to do with it's potential operating range. If so, for a given engine in the same climatic conditions at any particular time, a 5W50 oil will be at the same temperature as a 15W40, and hence the viscosity of both the oils at that temperature should be similar too. Therefore no extra loss of 5W compared of 15W oil.

Anyway, that's my understanding. I could be wrong.

The Baleno manual does not specifically mention using any particular grade. It recommends different oils for different temperature ranges.

[Jaggu]

5w50 is more tolerant than 15w40 and will hold its properties over a broad band of operating condition/temperature.

shuv: your spot on and baleno manual is also correct. either you use diff grade oils for diff temp (as per manual) OR use a fully synthetic oil with more tolerance to take care of it.

[kpzen]

Originally Posted by nitrous

I've learnt somewhere that xW40 starts losing efficiency at around 35 degree centigrade.

Thats not possible..Where did u read that?

[nitrous]

Kp,not the engine temperature. The ambient exterior temperature.

[kpzen]

Originally Posted by nitrous

Kp,not the engine temperature. The ambient exterior temperature.

Anna. I'm confused. How can ambient temperature of 35 degrees affect the efficiency of an oil that too a SAE grade engine oil?

[nitrous]

Well,I apologize since I dont have the theory.
But, this is the reason there is no xW30 oil sold in our country (barring the snowy regions which i dont know about). ok?

[kpzen]

SAE grade for Engine oils

[gemithomas]

Originally Posted by kpzen

SAE grade for Engine oils

Now how do i decipher the code

[71Convertible]

5Wx is a waste of money in most of India. It is not lower viscosity at the typical temperatures experienced so will provide no benefit at startup -- ie. 5Wx and 15Wx will have about the same viscosity for the temperatures in most of India. Just get a 15W50 or 20W50.


From the chart above -- at oil temp of 100C a 5W50 blend has Kinematic viscosity of 10.5 and a 15W50 blend is 10.9. At 25-30C ambient (which also equals oil temp at cold start), the viscosities will be higher, but the difference between the 2 blends will still be pretty small.
Even when

Byas

[nitrous]

^^ U're right,71convertible.
But, most of the fully synthetics we get here are 5W.
So, we dont have a choice.

[rranjith_kum]

Hi
i would like you add my bits
Nitrous anna,
the numbers in SAE grade don't mean any temperatures
its actually SAE's Viscosity numbers; all the grades of engine oil are tested at both the 100degree C (212 degree F) and at -18 degree C for winter grades


Deciphering the code:

the table gives us kinematic viscosity which is our main consideration when it comes to lubrication it is measured in centistokes (cSt) based on the figures obtained for the different grades we can choose the best needed oil.
if i am correct there are posts in our forum supporting to go for 20W50 oil instead of 20W40 oils which are recommended by the manufacturers which is quiet good provided their usage ... both of the oils are prepared for high temperatures but for winter temperatures like for about -10 degree C as per theory 15W40 or 20W40 itself is sufficient ...

[cyneverdie]

Originally Posted by nitrous

^^ U're right,71convertible.
But, most of the fully synthetics we get here are 5W.
So, we dont have a choice.

Tell me about it , wish there was a 15w50 oil available like in the USA where 15w50 mobil 1 extended protection IS being heavily pushed .

Have to say I was/am a mobil 1 fanatic , on my last oil change I went to 5w50 OWS fully synthetic oil , very very happy with it. I feel its lighter and really good stuff - "enhanced HP"

OWS also has a 5w40 HC or hydrocracked oil ie its not synthetic but its such a refined petroleum oil that due to laws its allowed to be sold as synthetic not fully synthetic but synthetic .
Its not synthetic it is petroleum but VERY processed and refined hence "allowed" to be sold as synthetic.

The 5w40 HC oil is MUCH lighter than 5w50 and gives IMPROVED hp or MORE hp basically than a 5w50.
So if your not in a hot traffic congested city like Bombay , do try it out.
I believe I personally need the fully synthetic stuff with higher protection levels myself.

Just my thoughts.
cheers people