For a product that is designed to endure extremes in temperature, lubricants are surprisingly susceptible to temperature changes whilst in storage. Adrian Hill, Automotive Products Manager at Morris Lubricants, explains more.
Today’s commercial vehicle lubricant formulations have been developed to stay functional under a wide
range of operating conditions. They are very stable and once the components (base oils and additive systems) are mixed together, they stay mixed.
Under normal circumstances, engine oils and transmission/gear oils are subjected to temperature extremes. Starting from cold and getting hotter as the equipment works up to running temperature, then they cool down again when everything is shut off. Whilst in use, this is not a problem for them. However, the way they are stored can have an adverse effect.
The biggest problem with storage is actually – believe it or not – the cycle from hot to cold, for which they are designed when in use. If a container is not sealed or stored correctly it actually breathes as the temperature around it changes. As the surroundings cool, moist air is drawn in through the closure and water begins to condense out and accumulate. Any lubricant in prolonged contact with water will start to degrade and ultimately its effectiveness as an engine oil or transmission/gear oil will be impaired and not provide the correct level of protection.
In use, mechanical systems such as engines and transmission/gear units also breathe and draw in moisture. However, as soon as the equipment begins to warm up through use, this water is driven off, allowing the lubricant to get on with its job. It is for this reason that manufacturers define distance or time in the service schedules, i.e. 30,000km or 12 months, whichever comes first.
If the engine has only done a couple of hundred miles in a year, the likelihood of condensed water building up is high and damage to the lubricant will take place – the same effect as leaving it stored with water in the container.
In this situation the oils should be drained and replaced every year. Of course, if the vehicle reaches 30,000km it has done a good job (the water being driven off regularly), but the lubricant still needs to be changed because it is now exhausted.
In summary, lubricant containers should be stored in a place with small fluctuations in ambient temperature (extremes should be avoided, too hot or too cold), under cover and with the closure/top/bung correctly placed back and tightened. They should be kept indoors or under an effective shelter. Larger containers, such as 205L drums benefit from being kept on their side, so the actual oil inside helps seal the drum from moisture ingress. If these basic principles are followed, the oil is likely to be 100% effective when used for topping up or for a complete service fill.
