What should be avoided when using petroleum-based hydraulic fluids?

Mixing petroleum-based hydraulic fluids with synthetic oils should be avoided because doing so can lead to compatibility issues that may compromise the performance of the hydraulic system. Different chemical properties between petroleum and synthetic fluids can result in destabilization, adverse reactions, or a breakdown of the fluid characteristics. This could lead to reduced lubrication properties, increased wear on hydraulic components, and overall system inefficiency.

In contrast, using petroleum-based fluids at low temperatures, storing them in opaque containers, or introducing air into the fluid can lead to problems, but they do not inherently risk the fundamental chemical interaction issues that arise from mixing different types of fluids. The performance of petroleum-based fluids at low temperatures might be compromised, but this is more about performance than immediate compatibility concerns. Storing hydraulic fluids in opaque containers is typically done to protect them from light exposure and does not directly affect their chemical properties. Finally, introducing air can lead to cavitation and reduce fluid efficiency, but again, this issue is distinct from chemical compatibility concerns that arise from mixing different fluid types.