You generally shouldn't try to thicken used motor oil for engine use. Using the wrong viscosity oil can damage your engine. However, there are instances where thickening oil might be considered, but only for very specific non-engine applications, and with certain caveats.
Thickening Oil for Non-Engine Applications
Some people use used motor oil for purposes like rust prevention or as a less expensive alternative to bar and chain oil for chainsaws. In these cases, thickening the used oil might be considered, but it's important to understand you are deviating from its intended use.
Methods to Consider (for Non-Engine Use Only):
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Additives: Some additives, like STP or similar oil thickeners, were designed to increase the viscosity of motor oil. However, the efficacy and long-term effects of these additives in used oil for non-engine applications are not well-documented. The effectiveness may vary based on the specific additive and the type of used oil. Using these should only be done after carefully checking the compatibility and intended use.
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Changing to a Thicker Grade (New Oil): Instead of trying to thicken used oil, consider using a fresh, heavier-grade oil initially for applications requiring thicker viscosity. This is a safer and more reliable approach than trying to modify used oil.
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Blending: Some users suggest blending used motor oil with other substances, but the results are unpredictable and may lead to undesired consequences.
Important Considerations:
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Used motor oil contains contaminants: Used motor oil contains metallic particles and other contaminants that can harm machinery. Filtering it might reduce the amount of contaminants, but never fully eliminate them. Using it in anything other than a purpose-designed application is risky.
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Environmental concerns: Improper disposal of used motor oil is harmful to the environment. Always follow local regulations for disposing of used motor oil.
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Safety: Used motor oil is a hazardous material. Handle it with care, using appropriate personal protective equipment (PPE), like gloves.
Why Not Thicken Used Motor Oil for Engine Use?
Motor oil degrades and thins with use due to shearing and fuel dilution. Attempting to thicken it for reuse in an engine is strongly discouraged. Using oil that is not the correct viscosity for your engine can lead to significant damage. Always consult your owner's manual for the recommended oil viscosity.
