Specific Gravity

[Mark888]

I have been trying to figure out what is the difference between regular Mobil 1 and Mobil 1 Extended Performance (Extended Protection). One thing I noticed is that in 5w30 and 5W-20, the regular Mobil 1 has a significantly lower specific gravity (what Mobil 1 calls density) than EP oils of the same weight, and also lower than competitors, and also lower than the other regular Mobil 1 oils in different weights.

Are there any experts (seriously, I mean real experts--guesses not allowed) who know whether there is any significance to these differences and how it effects oil performance?

Here is the data taken from manufacturer product or MSDS data sheets:

Specific Gravity, Water = 1.0 (called Density by Mobil)

Mobil 1 5w30 0.80
Mobil 1 Extended Performance 5w30 0.86

Amsoil 5w30 ASL 0.8571
Amsoil 5w30 XLF 0.8524
Castrol Edge 5w30 0.847
Castrol Syntec 5w30 0.854
Pennzoil Plat. 5w30 0.855

Mobil 1 5W-20 0.80
Mobil 1 Extended Performance 5w20 0.86

Mobil 1 0W-20 0.85 (Advanced Fuel Economy)
Mobil 1 0w30 0.845 (Advanced Fuel Economy)
Mobil 1 0W-40 0.855

 

[crinkles]

Mobil is correct in calling it either SG or density, because in metric, the units of all those numbers are just kg/L.

what makes the metric system nice.

but yeah last night i noticed the same thing about the apparent low density of Mobil 1 5w30 and it puzzled me.

sorry I am not an expert.

 

[Gary Allan]

Maybe Bruce or Mola will chime in. Chevron doesn't even offer a base stock of that low a density in either GroupII, II+, or Group III.

http://www.chevron.com/products/sitelets/baseoils/products.aspx

 

[mechtech2]

Typo by M1?

 

[Boomer]

That is gettting to be a pretty low density for a hydrocarbon!

 

[Tom NJ]

Density refers to mass/volume at a given temperature, usually expressed as g/ml or lbs/gal @ X degrees (Example: 0.85g/ml @ 15.6C).

Specific Gravity is a ratio of the density of a fluid over the density of water at given temperatures. Because it is a ratio, it has no units but the temperature of the fluid and the water must be expressed. (Example: 0.85 @ 15.6C/15.6C)

SG, when expressed in g/ml and the water is at 4C, will equal Density.

Some SGs @ 15.6C/15.6C for common base oils are as follows:

PAOs and Group III-------0.82-0.84
POEs-----------------------0.94-0.99
AN (5 cSt)--------------------0.91
150 cSt PAO-----------------0.85
Detergent Additives------->1.0

Mobil 1 Extended Performance claims to have more detergent additives and high viscosity PAO than regular M1, so this will raise the specific gravity. In addition, if it contains more POE and/or AN, this too will raise the specific gravity.

The 0.80 SG reported on regular M1 appears to be a typo.

Tom NJ