ASTM D2982 Test Methods for Detecting Glycol-Base Antifreeze in Used Lubricating Oils
4. Summary of Test Methods
4.1 The ethylene glycol is extracted from the sample with an acid solution and oxidized to formaldehyde with periodic acid which is detected colorimetrically with decolorized fuchsin.
5. Significance and Use
5.1 Leakage of glycol-base antifreeze into the crankcase is serious because the coolant tends to interfere with the lubricant and its ability to lubricate; it also promotes sludging. Ethylene glycol present in the coolant can increase varnish deposit formation in the crankcase as a result of glycol oxidation and the interaction between glycol and lubricant. Furthermore, because glycol is a higher boiling material than water, it will tend to stay longer in the crankcase oil than water. Lubricant displacement, sludging, and deposit formation all lead to engine malfunction and possible seizure.
5.2 These tests are designed to detect glycol-base coolant contamination even at low levels because early detection enables corrective measures to be taken to prevent leaking coolant from accumulating and seriously damaging the engine.
5.3 These test methods are also significant because the reagents can be packaged as a field kit, and the procedure can be followed at the site where there is a concern.
6. Interferences
6.1 The reactions are not specific to ethylene glycol; other 1,2-glycols and many carbohydrates will give a positive test.
6.2 Hexylene glycol and methoxy glycol, which are often used as gasoline anti-icing additives, do not interfere when present in gasoline-diluted used oils.
6.3 Oil oxidation products present do not interfere with the test.
6.4 Some new oils can contain small amounts of glycol derivatives as part of their makeup and thus give a positive test. These oils, after use, invariably give a negative or trace reaction as the glycol derivatives are slowly destroyed under conditions of use in the engine.
6.5 A modification is described in Procedure A for removing interferences caused by carbohydrates such as sugars and sugar-containing substances that are sometimes used for sabotage purposes.
