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Lube Filtration Strategies

Our Strategy for Superior Lube Filtration

For clean engine oil at a reasonable cost, Donaldson engineers typically recommend using a full-flow filter with advanced Donaldson Synteq™ media technology. Our industry-leading Synteq media offers higher efficiency than standard cellulose media at the same or lower pressure drop. With this solution, you get fluid that is as clean (or cleaner) than two-stage filtration, without the added cost, maintenance and packaging space of a multi-filter system.

An added benefit of this strategy is that oil becomes cleaner faster and stays cleaner because 100 percent of the flow is continuously filtered through high-efficiency media. Cleaner oil delivers greater engine protection – without the increased restriction of traditional full-flow systems that use cellulose media. Using this strategy, the full-flow filter can often be the only filter in the system, which saves on overall first fit system costs, as well as ongoing maintenance costs for your customers.

What About Using Multiple Filters?

With a full-flow filter, you’re trying to balance efficiency and restriction. You want a filter that’s more efficient, but if it’s too efficient, you end up going into filter bypass more often. This can be detrimental because unfiltered oil circulates to the engine more often. What many engineers do is take the high-efficiency filtration and put it in a flow bypass (kidney loop) outside the full-flow filter. That way it’s not restricting flow to critical engine components.

A typical diesel engine lube circuit with both full-flow (1) and by-pass (2) filters installed.

Two filters is a great solution, but a combination of a full-flow filter and a bypass filter is also a more expensive one. Two heads, plumbing and filters (rather than a single full-flow filter) require more space on the engine and increase maintenance cost.

Whether you choose to apply a full-flow filter independently or incorporate a bypass filter, we offer advanced solutions to meet the needs of all system configurations.

Typical Lube Filtration Strategies
1. Full-Flow Filtration
  • Processes nearly 100% of the regulated flow
  • Is the most common lube filter available
  • When combined with advanced Donaldson Synteq media, can provide essential engine protection for maximum cold-flow performance and filter life
2. By-pass (Secondary) Filtration
  • Around 5 to 10% of the system’s oil flow is diverted back to the sump or oil pan before reaching the primary filter
  • Captures smaller particles than the full-flow filter
  • Increases efficiency but is more restrictive
  • Can be located in a separate flow path to optimize restriction 
  • A metering orifice is commonly used to meter the flow of oil through the by-pass filter
3. Two-Stage (Combination) Filtration
  • Attempts to combine the features of a full-flow and bypass filter
  • Two-in-one design significantly increases restriction, causing shorter filter life and decreased cold-flow performance
  • Poor cold-flow performance can starve the engine of oil during start-up, leaving the engine temporarily unprotected
  • This may lead to increased engine wear that could result in premature repairs or even engine replacement
  • This approach is not typically recommended
An Important Note About Lube System Pressure

Maintaining appropriate pressure within the system is critical for overall function and helps maintain effective filtration performance. To make sure that components are not damaged during operation, most lube systems include a pressure regulating valve that continuously regulates pressure under all temperature and flow conditions. If the system pressure gets too high, it could rupture seals, filters or other components, potentially causing catastrophic damage. High-pressure relief valves have a similar function – serving as the backup system to the pressure regulating valve.

Questions on how our technologies can benefit your business?