As discussed in “Additives: To use or not to use”, you generally shouldn’t add aftermarket additives to your lubricating oils. However, it is important to remember that your lubricating oils already come with an additive package formulated into the oil.
Lubricating Oils and Additives
When formulating lubricating oils, manufacturers know what they are doing. They know their base stocks and the chemistry behind the additives. Additives can comprise around 0.1% to 30% of a finished lubricating oil to create the right formulations for specific machine components and applications. It’s the additive package, not the base oil, that makes the lubricant work for a hydraulic application versus turbines, bearings, or engines.
In general, the base oil does the lubrication while additive packages enhance, suppress, or impart new properties to the base oil. For example, engine oils generally have a higher concentration of additives to combat operational conditions such as soot, oxidation, corrosion, and wear. Steam turbine oils, on the other hand, have a much lower concentration of additives which focus on reducing water concentration.
| Component Type | Common Additives | Concentration (By Volume) |
|---|---|---|
| Engines | Detergents, oxidation inhibitor, corrosion inhibitor, anti-wear (AW), anti-foam, viscosity index improver, alkalinity improver | 10% – 30% |
| Gears (spiral, bevel, or hypoid) | Anti-wear (AW), oxidation inhibitor, anti-foam, sometimes corrosion inhibitor, extreme pressure (EP) | 1% – 10% |
| Hydraulics | Oxidation inhibitor, anti-wear (AW), anti-foam, corrosion inhibitor, pour-point depressant, viscosity index improver | 2% – 10% |
| Gears (worm) | Extreme pressure (EP), oxidation inhibitor, corrosion inhibitor, friction modifier | 3% – 10% |
| Steam Turbines, Compressors | Rust inhibitor & oxidation inhibitor (R&O), demulsifier, anti-foam | 0.1% – 5% |
Aftermarket Additives
When it comes to aftermarket additives, there is a lot of conflicting information available. Some aftermarket additive manufactures claim their products will “give more horsepower”, “improve fuel economy”, or provide “better sludge control”. These claims are often inflated or unproven. They may also neglect to advise of negative effects that could happen if you added these extra additives to your oils.
Issues with Aftermarket Additives
The addition of an aftermarket additive package into a formulated lubricating oil can significantly impact the performance and disrupt the balance of existing additives. You can encounter a number of problems including:
- Concentration imbalance: Improving a one property (horsepower) while degrading another (wear) and affecting the overall oil quality.
- Competition: Creating a situation where additives compete for the same space on a metal surface (anti-wear vs corrosion inhibitors) causing early component degradation due to corrosion or other issues.
- Settling: Oils can only dissolve additives to a certain saturation level. By adding more to an already saturated oil, the additives may settle out and be sitting in the bottom of a reservoir adding no value.
Just like base stocks, additives may be of higher or lower quality resulting in higher and lower quality finished lubricants. An inferior oil cannot become a better oil by adding more additives. Instead, aftermarket additives can disrupt the fine balance of the chemistry of oil formulations and cause harmful effects to lubricants and equipment. This can create issues which may lead to the voiding of warranties because the new oil formulation created from adding the aftermarket additive isn’t approved for use.
Essentially, if you want better oil, you buy better quality oil.
Final Note
Lubricant oils are specifically formulated with the right concentration of additives by oil manufacturers to keep your equipment protected and running smoothly. However, lubricating oils do degrade over time as additive packages are used up.
It’s beneficial to regularly test your oils to determine the remaining useful life so you have an insight into when an oil change will be required. If you decide to use an aftermarket additive package, do so at your own risk. You should always consult with your lubricating oil manufacturer and OEM before proceeding to ensure you do not void your warranties or create additional problems for your equipment.