"We have a customer who adds additives to our oils to boost the viscosity and base number. Our recommendation is to change the oil every 10,000 miles, but the customer adds the additives so he can run the oil for 25,000 miles. What could happen when doing this? The used oil analysis results always show a base number that is higher than the fresh oil base number, as well as a higher viscosity and sometimes a low base number. The iron is also higher than other customer reports. Could these results be caused by adding the additives?"

Changing your oil can be very expensive, sometimes exceeding 40 times the cost of the oil. There can also be problems like using contaminated or incompatible oil. The aging process for oil is very similar to that of the human body. Therefore, when you expose a lubricant to elements within the machine, such as heat, water, air or other contaminants, irreversible damage can occur.

While base oil doesn’t wear out, the longer it runs in your machinery, the less effective the additive packages will be. This results in viscosity increases, sludge and corrosive acids attacking metal surfaces and bearings. Using lower quality lubricants can cause these problems to ensue much faster.

Although additives can extend the life of a lubricant, they can’t prevent aging and degradation. Adding additives can also upset the lubricant’s formulation balance.

There are ways to restore depleted additives in order to extend oil change intervals. One way is by additive reconstruction, which involves introducing an additive concentrate to in-service oil. This is usually applied to machines with large oil volumes such as compressors or turbine oils. However, additive reconstruction should only be done after lab testing has confirmed that adding a supplement will not impair the performance of the lubricant’s other properties.  

Another option is a bleed-and-feed partial oil change, which is used when changing the oil is risky or inconvenient. It involves draining a portion of the oil volume and then immediately introducing the new oil. Doing this can remove some of the contaminants and introduce fresh additives.

A baseline test should be performed on any new lubricants to provide a reference and to help determine the oil’s quality so you can catch problems before they become catastrophic. Used oil that has a higher base number than the fresh oil is indicative of detergent being added to the old lubricant. Higher viscosity at extended service intervals can mean the original viscosity index improvers in the lubricant may have sheared. An increase in iron reveals abnormally high wear, which can result in severe damage to any part of the machine that comes in contact with these objects.