A reader asks: We have a variety of compressor and hydraulic systems in our plant. Our technicians frequently complain about difficulty with seeing clear oils in sight glasses. We’ve even had situations where production has been temporarily halted because we mistakenly believed that a reservoir was below the safe level. Do you offer a coloring that darkens the oil? It would help us with “hard to see” oil levels on sight glasses.

Our Answer: There is a product for coloring oils that is readily available. Heavy-equipment maker Caterpillar offers oil-soluble dyes that are suitable for most compressor, hydraulic, R & O and transmission fluids.

We have spoken to people that have had very good results with this product in hydraulic oil reservoirs. It immediately makes clear oils much more visible in sight glasses and on dipsticks.

These dyes are available from most CAT heavy-equipment dealers. CAT dealers are located all over the world. Please note that we do not sell CAT brand oil dye and have no affiliation with Caterpillar Inc.

Applications And Mixing Directions For CAT Oil Dye

Caterpillar Oil Dyes are available in the colors blue or red. They are soluble with most industrial hydraulic, compressor or gear oils where increased visibility is desired. It is best to consult your CAT dealer to ensure that the dye product is compatible with your intended application.

The recommended mix ratio is 16000:1. This means that 1 US ounce of dye will treat 125 US gallons of oil. The metric ratio is 6 milliliters of color to 100 liters of oil.

The Cat dye container size is 8 US ounces (240 ml). The entire container can treat 1000 US gallons (3785 liters) at the recommended mix rate.

Cat Oil Dye Part Numbers

Blue dye- New part number: 486-1536 (Old part number: 9U-5032)
Red dye- New part number: 486-1535 (Old part number: 9U-5031)

A Warning About Using Oil Dyes

Oil dyes are generally very concentrated. It is vital to wear gloves when handling oil dyes. Any contact with skin could lead to long-term staining.

In conclusion, oil dyes are an easy, safe and commonly found solution for clear industrial fluids.