GLYCOL ANTIFREEZE IN USED LUBRICATING OILS: ASTM D2982
EXPLANATION
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, increases varnish deposit formation, and it will stay longer in the crankcase oil than water due to its higher boiling point. All this will lead to engine malfunction and possible seizure.
These tests are designed to detect glycol-base coolant even at low levels because early detection enable corrective measures to be taken to prevent leaking coolant from accumulating and seriously damaging the engine.
Another procedure, Test Method ASTM D4291, is also used for the determination of ethylene glycol in used engine oils.
TEST SUMMARY
Two test procedures are available: one employing reagents in tablet form, the other employing laboratory shelf reagents. 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.
These tests methods will also detect other 1,2-glycols and carbohydrates that may be present. Hexylene- and methoxy-glycols, which are often used as gasoline anti-icing additives, do not interfere. Oil oxidation products present do not interfere. A modification is described for the tablet procedure for removing interferences due to carbohydrates such as sugars and sugar-containing substances that are sometimes used for sabotage purposes.
TEST PRECISION
These are qualitative pass-fail tests, and the normal precision estimates do not apply. The tablet procedure is sensitive to about 100 mg/kg and the shelf reagent procedure to about 30 mg/kg of ethylene glycol. Both procedures are adaptable to field kit use and commercial field testing kits are available.
