Wear Relationship to Motor Oil Density

[AEHaas]

I have been looking up data on oil density. There is information that suggests that this is very important in relation to wear. The higher the density the lower the wear rate. I believe it has to do with a thicker oil film despite a lower kinematic viscosity. For 5W-20 wt oils here is the data I got so far

Castrol Syntec 5W20 ........density..... 0.848
Mobil 1 5W20 ..................density..... 0.80
Mobil 1 0W20 ..................density..... 0.84
Motorcraft 5W20 ...............density..... 0.852
Pennzoil Platinum 5W20 ....density..... 0.851
Red Line 5W20 ................density..... 0.888
RLI 5W20 .......................density..... 0.88
Valvoline 5W20 ...............density..... 0.86
Valvoline SynPower 5W20..density..... 0.853

Here are some others:

Castrol Syntec 0W30 - 0.847
Castrol Syntec 5W40 - 0.855
Castrol Syntec 5W50 - 0.852
Castrol Syntec 20W50 - 0.862

Mobil 1 5W30 - 0.80
Mobil 1 0W30 - 0.845
Mobil 1 0W40 - 0.855
Mobil 1 15W50 - 0.87

Notice that the Red Line oil, thought by some to be the best for high loads, has the highest density of all these oils. I always liked the 0W20 Mobil 1 but had reservations about their 5W20. Note that the 0W20 has a higher density. Note that the Motorcraft is one of the higher ones.

aehaas

 

[Pablo]

Quote:

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There is information that suggests that this is very important in relation to wear. The higher the density the lower the wear rate.

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Can you post this? Very interesting.

 

[G-MAN]

I don't know how much I'd read into this. Of the oils you listed, only Redline (and possibly RLI) are Newtonian, which means their density is not being affected by the addition of VI improvers.

 

[AEHaas]

I do not know the resources at this time. I just remembered reading about the relationship several times in the past. I made mental notes but did not commit to researching it further. I figured I would look into it at some point. That time is now. I will present the data as I collect it.

aehaas

 

[Vaca]

Is the density measurement the same as the Specific Gravity measurement?

The reason I ask, is that looking at the Pennzoil conventional specs on the website shows, for instance, the Specific Gravity @15.6C to be .862 for 5W-20. That's awfully close to the gravity measurements posted on this thread. Maybe just a coincidence?

 

[Pablo]

Quote:

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Is the density measurement the same as the Specific Gravity measurement?

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The same - Density of pure water = 1.00 (gm/ml or cc) Water SG = 1.000 (standard temp and pressure)

Another view, H2O = 8.33 #'s/gallon.

 

[Pablo]

Density is a function of ingredients of course. Lots of high SG base oils, additives, and LESS light poly VII and LESS light PP agents should be good oils. So there probably is a sweet spot for a given engine – within this density sweet spot one oil may outperform another, depending on all the other variables we haggle about daily.

 

[INDYMAC]

The standard deviation of the examples listed look so small, that I really wonder whether there is anything worth looking into here.

 

[bruce381]

Problem with all this is that density aside NONE of the oils have a known "standard" or the same add pak as well as base stock types and viscosity to just look at used oil analysis to corrolate wear numbers that adds in the error of lab and engine/driving/operational conditions this is not a vaild comparision at all.
bruce

 

[mechtech2]

It makes sense to me that more density would allow more pressure before failure.

 

[AEHaas]

Some have argued that a HTHS of 3.5 will prevent wear while a value of 3.2 is not sufficient. The difference between a density of 0.80 and 0.89 has a similar spread. Maybe there is a dividing line here somewhere.

For me it is just one more thing to watch for. If I was considering between 2 oils with similar properties but one had a higher density then it may be the item that tips the balance.

I have not considered the use of RLI lubricants in the past. Now that I see it has a high density I will look at it more closely.

aehaas

 

[buster]

Much like studying economics in college, most theories were always holding other variables as constant. Point is, you can single out a lot of different factors such as additives, base oils and the often debated viscosity, but what ultimately makes an oil good is the complete formulation. It's definitely interesting though to look at.

 

[BigAl]

Kinematic viscosity is a measure of the resistive flow of a fluid under the influence of gravity. In order to have the same kinematic viscosity as a less dense fluid, a more dense fluid would need to have a higher resistance to flow . . . a higher dynamic (absolute) viscosity. So I believe that for once, Dr. Haas is indicating that thicker oil is better.

Very interesting!

 

[Dad2leia]

Given that density can play this role, is the HTHS still as an important component factor to figure as highly as the density? I realize that is a well formulated lubricant, there are many trade offs and comprimises, but doesn't there come a point where we are actually splitting the already split hairs of the oil itself in its ability to function properly?

BigAl, I would be very surprised if Dr. Haas would actually recommend thicker totally, as I loved the thread about him running a 20 weight in the Lambourghini!

 

[boxcartommie22]

i have some more specific gravity densities relative to water:

redline 10w30-0.892
redline racing 30w-0.901
mobil delvac 1 5w40-0.854
torco sr-5 5w40-0.86

 

[boxcartommie22]

here is another:
maxima ultra 5w40-0.87

 

[bruce381]

Hey Doc I have base fluid that are up to 1.2 SG loaded with Phos at a vis @100 4-5.
bruce

 

[Dad2leia]

That stuff will grow hair on your engine Bruce!!!

Does it have all the goodies in it as well?

 

[AEHaas]

'Might make an interesting experiment.

aehaas

 

[buster]

Quote:

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Castrol Syntec 5W20 ........density..... 0.848
Mobil 1 5W20 ..................density..... 0.80
Mobil 1 0W20 ..................density..... 0.84
Motorcraft 5W20 ...............density..... 0.852
Pennzoil Platinum 5W20 ....density..... 0.851
Red Line 5W20 ................density..... 0.888
RLI 5W20 .......................density..... 0.88
Valvoline 5W20 ...............density..... 0.86
Valvoline SynPower 5W20..density..... 0.853

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Does it correlate to the used oil analysis we have? I'm thinking it might.