Mobil 1 Engine Oil

[mosoto]

bummer about the sougi. "Was" a good oil. For Australian conditions and normal street use the 10w40 would be absolutely fine in a synthetic.

[Bourbon Boy]

Maybe we are just confusing terms? In my understanding when oil get so hot it starts to break down (deteriorate), it means the oil is failing, it damages the oil and can cause engine damage. I would expect this would be somewhere beyond 200degC..

I am assuming you just mean the oil thins as he heats up? the oil viscosity will continue to reduce as the oil heats beyond 100degC, but I wouldn't classify that as 'deteriorating'.

A little clarity required here.

The first number is the viscosity when cold i.e at cold start. eg 5 weight or 10 weight. Yes thats what the W is for.

The second number is the viscocity at operating temperature eg 30 weight or 40 weight.

So it depends on how "thick" you want your oil at start up and op temp. depending on environment & driving conditions.

It has absolutely nothing to do with the point where oil breaks down LOL.

YES Guys, thats what I meant! I guess sonicii is right... its just my way of putting it. Sorry my England not so good... lol.

[sonicii]

The first number is the viscosity when cold i.e at cold start. eg 5 weight or 10 weight. Yes thats what the W is for.

As a general rule, a lower number will generally mean a thiner oil at low temp, but that is not actually what the first number specifies. It actually specifies a temperature, not a viscosity. It is the coldest pour point of the oil. The temperature at which the oil becomes so thick it, Can't be Poured/pumped.

Edited January 6, 2012 by sonicii

[mosoto]

As a general rule, a lower number will generally mean a thiner oil at low temp, but that is not actually what the first number specifies. It actually specifies a temperature, not a viscosity. It is the coldest pour point of the oil. The temperature at which the oil becomes so thick it, Can't be Poured/pumped.

Really??? as an example have a read greg. Both numbers are cold & hot viscocities. The first number is not a temp but a cold viscocity, the second number is the hot viscocity measured at 210º

http://www.upmpg.com...roil_viscosity/

Edited January 6, 2012 by mosoto

[sonicii]

http://www.zddplus.com/TechBrief13%20-%20Oil%20Viscosity.pdf

[PM-R33]

A little clarity required here.

The first number is the viscosity when cold i.e at cold start. eg 5 weight or 10 weight. Yes thats what the W is for.

The second number is the viscocity at operating temperature eg 30 weight or 40 weight.

So it depends on how "thick" you want your oil at start up and op temp. depending on environment & driving conditions.

It has absolutely nothing to do with the point where oil breaks down LOL.

Just thought I would jump in and correct that. Common misconception that the W stands for weight. It actually stands for Winter, meaning it will still flow enough to start the vehicle in sub zero temperatures.

[mosoto]

yeah we have sussed that in the previous link. It's a mistake from my shock building days.

[mosoto]

http://www.zddplus.c...20Viscosity.pdf

Page 6 under Multi-Viscosity oil proved my point, I'm just wondering why you posted it if you did so in support of your argument .

Let's not detract from the fact we are talking about what the two figures mean NOT how they were tested to attain those figures.

So my original comment stands. The first figure is the cold viscosity, the second figure is the hot.

This subject has been done to death on these forums and yet everyone STILL agrees to disagree on all things oil LOL.

i'm out....................

Edited January 6, 2012 by mosoto

[sonicii]

page6 does not refute my argument, under the multi-viscosity oil section it specifies oil with such designation has undergone both sets of tests, the low temp test and the high temp tests. Page 5 shows the low temp tests and specifies how the 1st number is obtained, it is a measure of a specific viscosity, but they adjust the temperature of the oil to obtain a low temp pumping viscosity of 60,000cP. The first number specifies the temperature that viscosity is achieved (As well as matching other criteria). The 2nd number is a straight viscosity measurement at 100degC (although must also match 150degC viscosities).

So yes, the first number is a measurement of viscosity at low temp, but it is a measurement of what temperature a specific viscosity is achieved, not a measure of viscosity at a fixed low temperature.

So as I said before, a oil with a lower xxW number will most likely have a lower viscosity at a specific low temperature (0degC for example), but that is not what the number actually means.

Edited January 7, 2012 by sonicii