Varnish Deposits

Varnish Deposits Case Study


A leader in plastic injection molding industry had been experiencing the formation of varnish deposits in their machines running on a competitor’s standard AW (anti-wear) ISO 46 hydraulic oil. Varnish causes operational issues – production downtime, fluid & labor costs, machine rebuild parts, and limited oil life – that is costly for the customer with new valves costing as much as $10,000 apiece. In recent years, the customer has developed a more proactive method to manage their hydraulic oil systems utilizing BENZ MACHINE CLEAN 23 to dissolve the varnish before an oil change. This process comes with a cost of cleaning out the system but reduced downtime by 40 hours versus the traditional methods of running the oil to failure.

Customer Stated Goals
• Reduce varnish formation
• Increase time between oil changes
• Eliminate the use of a machine cleaner
• Increased production time
• Being proactive in addressing varnish issues


Increased temperatures, such as plastic injection molding hydraulic systems, accelerates oxidation (oils reaction with oxygen), but it is difficult to predict when the adverse consequences will impact mechanical operations with varnish deposits. The detection of oxidation has often been linked to varnish formation, but Benz research has shown that some fluids varnish heavily with very little oxidation detected while other fluids may be heavily oxidized and produce little or no varnish. To be predictive, a combination of test methods must be utilized before degrading consequences of viscosity increase, odor, color change, and varnish deposits become apparent. ECLIPSE VR series is designed to minimize the varnish potential in high heat hydraulic systems, such as injection molding operations.

Benz laboratory research developed testing standards that allowed the development of ECLIPSE VR series by degrading the fluid in a predictive way and testing its varnish levels via MPC (Membrane Patch Colorimetry) testing.


Customer moved to utilizing ECLIPSE VR 46 in a machine that has been known to have issues with varnish and valve failure. Over the past year running on ECLIPSE VR 46, customer has seen uninterrupted production and no unscheduled downtime. Machine performance and oil condition is closely monitored for change. After 1 years run time on ECLIPSE VR 46, this system is still extremely clean and varnish free, with a MPC value of < 5ΔE, considerably lower than the ‘monitor’ level.

Projecting two-times increase in the time between oil changes, ECLIPSE VR 46 solution will save the company $3000 per year on hydraulic oil usage on this machine alone. Include valve repair, labor, and lost production time across their multiple machines, that savings figure will increase, estimated at $60,000 annually for this customer. Recognizing the need for change, this plant is shifting to ECLIPSE VR 46 that is moving their maintenance program to a more proactive philosophy.