Diester Compressor Lube

[MolaKule]

This is a 100% di-ester compressor fluid produced by Amsoil about
12 years ago, and came out in their rectangular and clear plastic bottle.
(Will have some pictures of fluids soon).
I still have about 1.5 quarts of it left, which is why I am still using
it. I do not know the product code, since the product code was not on the label.

As you can see, this fluid is a non-detergent fluid and has only a phosphorus AW add and some anti-foam add, with a smidgeon of tin, most likely a tracing element. Most of the FM and lubricity is accomplished by the di-ester base oil. Viscosity shows it to be an SAE 30 weight. Not much else to say about this ancient di-ester.


Iron (Fe) 0
Copper (Cu) 0
Chromium (Cr) 0
Aluminum (Al) 0
Lead (Pb) 0
Tin (Sn) 3
Silicon (Si) 4
Sodium (Na) 0
Potassium (K) 0
Molybdenum (Mo) 0
Phosphorus (P) 443
Zinc (Zn) 0
Calcium (Ca) 0
Magnesium (Mg) 0
Physical


Water (W) N
Fuel (F) N
Antifreeze (A) N
Viscocity At 40 C (V40) 0
Total Acid Number (Tan) 0.5
Total Base Number (Tbn) 1.5
Viscosity At 100 C (V100) 12.6
Oxidation 0

Particle Counts
5 µ (5µ) 55
10 µ (10µ) 21
15 µ (15µ) 11
20 µ (20µ) 6
25 µ (25µ) 4
50 µ (50µ) 1
75 µ (75µ) 0
100 µ (100µ) 0
Iso Code Rating (Iso) 13/11

[ June 05, 2003, 11:47 AM: Message edited by: MolaKule ]

 

[Last_Z]

TBN of only 1.5?? I thought Esters were supposed to have a high TBN number....or is that some other type of Ester?
Rick

 

[MolaKule]

Esters in and of themselves are only fairly alkali.

Consider the application and specifications for a compressor:
1. Compressors see no combustion gasses.
2. No acids from combustion are formed.
3. Therefore, no detergents are needed, hence the ND specification for compressors. The Dispersant-Detergent package is what carries the acid fighting capabilities of the oil, hence a low tbn for this oil.

Now what the compressor does need is an oil with good lubricity and an additive package consisting of:
1. Rust and oxidation inhibitor, chemicals not showing up in this analysis.
2. Antifoam - silicon
3. Mild EP additives, so about 300-500 ppm of phosphorus is about all that is needed.

 

[Neil Womack]

Wouldn't a little antimony be a good thing in compressor oil for its antirust properties?

My little one lung compressor calls for SAE 30 non-detergent motor oil changed 2x year. When I drain it a small amount of water bubbles out with the oil. Emulsification does not seem to be a problem.

 

[MolaKule]

Yes, or even some ZDDP if the iron levels were going up.

So far, I have not seen any elevated iron levels in my two-lung compressor.