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"Do you feel that it is necessary to agitate oil that is stored in larger containers such as drums to avoid a situation where some of the critical additives may settle in the bottom of the container?"
It is quite possible to agitate or mix the oil in a drum to redissolve additives, but if you are aware that additives have settled out of the oil, you should seriously consider returning the drum (or any container) of oil back to the supplier.
With the exception of certain gear oils that contain solid, suspended extreme pressure (EP) additives, most additives in lube oils are liquids, which easily dissolve into the base oil with a little heat and mixing during the blending process. A few additives may be in the oil as a suspension (for example, silicone-based anti-foam additives), but they should not settle out under normal circumstances.
If an additive is placed into the oil at too high of a concentration, the excess amount of additive could settle out, particularly at colder storage temperatures. However, this would not be considered normal.
The type of base oil used in the finished product will also have an impact on the additive solubility and thus any separation and settling. Group I base stocks are some of the best at dissolving additives, while polyalphaolefins (PAOs) are at the poorer end of the scale.
Whether you store lubricants in a 10,000-gallon tank or in 55-gallon drums, it is important that the lubricant’s quality is not tainted by contamination or additive settling. To ensure that lubricants stay in an optimal condition, determine how much lubricant should be stored at one time. To aid in this process, certain factors must be considered, such as:
The Lubricant Consumption Rate — Consumption will vary greatly depending on industry and equipment type. To ensure that the right lube quantities are being stored at a facility, you must determine the consumption rate. There are many factors that contribute to consumption, ranging from leaks to excessive drain-and-fill tasks.
The Lubricant Storage Capacity — The required lubricant storage capacity depends on consumption, but often there are too little or too many lubricants stored at one time. The proper storage capacity should maximize shelf life but allow for a certain percent excess of critical lubricants to be stored for emergency situations.
The Lubricant Supplier Turnaround Time — A lubricant supplier’s turnaround time should be a metric used to aid in determining the quantity of lubricants stored. If there is a short time interval between deliveries, fewer lubricants can be stored on site; however, if there is a lengthy time interval between deliveries, the quantity of lubricants stored on site should account for this.