Some of clients have noticed that their lubricant color are different than before when n it has been used for a while or even not used yet.

  Your lubricant's color change could be due to several factors as follows:

Normal operational changes:

OXIDATION:

CONTAMINANT COLLECTION:

ADDITIVE DEPLETION:

LIGHT FACTORS:

Potentially concerning causes:

Does Color Change Affect Lubricant's Performance?

Color Changes That Do Not Affect Performance

Color Changes That May Affect Performance

	Color Change	Cause	Performance Impact
1	Dark brown/Black	Oxidation	Increased oil viscosity Reduced heat transfer efficiency Formation of sludge that blocks oil passages Diminished additive effectiveness
2	Milky white/Creamy	Water or coolant contamination	Reduced oil film strength Increased corrosion risk Hydrogen embrittlement in metals Promotion of oxidation and bacterial growth
3	Lighter color/Thinning	Fuel dilution	Decreased oil viscosity Reduced oil film strength Lower flash point Increased potential for wear
4	Metallic sheen	Excessive metal particles	Indication of abnormal wear already occurring Potential for abrasive wear as particles circulate Possible blockage of oil passages
5	Color change with sludge	Additive depletion/decomposition	Reduced resistance to corrosion, wear, and oxidation Impact on viscosity stability Decreased extreme pressure performance

Conclusion

The color change of lubricants by itself does not directly affect performance, but it often serves as an important indicator of equipment condition. Gradual, normal color changes are acceptable, but sudden or unusual color shifts may indicate issues that need attention.

For professional equipment and critical applications, regular oil analysis is recommended rather than relying solely on visual inspection to determine lubricant condition. Oil analysis can accurately detect contaminants, wear particles, and the degree of oil degradation, providing a more scientific basis for determining when lubricants need to be changed.