Navara Oil Degradation

The symptoms you describe, particularly the oil pressure warning combined with a darker oil color, do suggest potential oil degradation or contamination. Has the engine oil been changed according to the manufacturer's recommended intervals? Oil sludge, as you mentioned, can restrict oil flow, leading to low oil pressure. Have you used any oil additives recently, as these can sometimes affect oil viscosity?

The oil changes have been performed, but perhaps not as diligently as the maintenance schedule stipulates. I haven't used any additives. Could infrequent oil changes alone account for such significant contamination, or are there other potential factors, such as fuel dilution, that I should consider?

While other factors such as fuel dilution could contribute, exceeding the maintenance interval is a very probable cause for the oil degradation you are observing. Infrequent oil changes allow contaminants to accumulate, which accelerates wear and sludge formation. Given the symptoms, I would advise consulting with a qualified mechanic for a thorough inspection and oil analysis. It is crucial to address this promptly to prevent potential engine damage.

I consulted with a trusted mechanic. The diagnosis confirmed significant oil degradation due to exceeding the maintenance interval, needing an oil change and engine flush. The final repair cost was 165€.