How to choose a diesel lubricity improver

Choosing a diesel lubricity improver starts with the fuel, the required test result, and the conditions in which the additive will be stored and used. Cestoil’s Northshore COLI range provides fatty-acid, ester, and blended options so that selection can reflect the application.

Start with the fuel and the performance target

Deeply refined diesel can need additional lubricity to support fuel-system components operating under boundary lubrication. A lubricity improver helps address this requirement through surface-active chemistry. The practical question is which product, at which dosage, gives an acceptable result in the fuel being treated.

Begin by measuring the untreated fuel and defining the target required by the customer, contract, or applicable specification. The high-frequency reciprocating rig (HFRR) test provides a wear-scar measurement for comparing untreated and treated samples under defined conditions. A lower wear-scar value indicates improved lubricity in that test. It should be interpreted with the test method and sample conditions, rather than as a direct prediction of equipment life.

Match the chemistry to the operating priorities

Cestoil’s 2026 lubricity-improver brochure describes five featured Northshore products from the broader range. The following distinctions help identify candidates for evaluation; they do not replace fuel-specific testing.

• COLI9500: A soybean-derived fatty-acid option for conventional ultra-low-sulfur diesel applications. It provides a useful starting point when comparing lubricity response and handling requirements across the range.
• COLI9500E: An economical soybean fatty-acid option for applications where cost is a priority and low-temperature handling requirements are less demanding. Despite its suffix, COLI9500E is not the ester grade. Compare its storage and dosing requirements with COLI9500 before selecting it.
• COLI9500ES: The ester-based option, worth evaluating when additive-package compatibility and handling behavior are important selection criteria. Confirm its performance in the complete intended formulation.
• COLI9500H: An acid–ester blend for evaluation where the untreated fuel has a demanding lubricity requirement and dosage optimization is a priority. Establish the required dosage through a comparative test series.
• COLI9510: A tall-oil fatty-acid (TOFA) option for customers who prefer this established chemistry or need to maintain an existing formulation approach.

Compare the Northshore lubricity-improver range to shortlist products before requesting samples. Providing the current chemistry, if known, also helps Cestoil make the comparison relevant to an existing treatment program.

Use test data as a starting point for evaluation

The COLI9500 results below are reported in Cestoil’s Lubricity Improver_2026 brochure. They illustrate responses in three specific diesel samples. The sample descriptions and dosages are retained so the figures can be interpreted in context.

These are sample-specific results reported in Cestoil technical material, not a guaranteed response for other fuels. They should not be used to claim that a particular dosage will always meet a specification. Request the supporting test information when assessing whether the examples are relevant to your fuel.

Build a dose-response comparison

A practical evaluation compares an untreated control with several agreed treatment levels in a representative fuel sample. Use the same preparation procedure and test method for each candidate. Include the existing additive, where available, so the comparison answers a purchasing question as well as a technical one.

Review the results against the required target and the variability expected in the fuel supply. The preferred treatment should provide an appropriate operating margin, not simply the lowest single result obtained in one test. Reassess the dosage when the fuel source or blend changes materially.

Compare treatment cost using the dosage established in your fuel and the quoted product price. A lower additive price does not automatically mean a lower cost per tonne of treated diesel; equally, a higher claimed efficiency does not establish a saving until the required dosage has been measured. Cestoil can help structure this comparison for the shortlisted grades.

Check handling, compatibility, and distribution requirements

Low-temperature selection needs the actual storage, transfer, and injection conditions. A published pour point is a material property; it is not, by itself, a guaranteed minimum pumping or storage temperature. Share the lowest expected temperature and dosing arrangement so the product’s handling guidance can be reviewed before a trial.

Evaluate compatibility with the complete additive package, including the intended concentrations and sequence of addition. Results obtained in a particular mixture do not establish compatibility with every cetane improver, detergent, or other component. Observe the blend under relevant storage conditions and confirm that the treated fuel continues to meet the required quality criteria.

For pipeline applications, Cestoil’s 2026 brochure identifies COLI9500, COLI9500E, and COLI9500ES in its EI 1535 qualification information. Request the current documentation for the exact grade and confirm the pipeline operator’s requirements and applicable conditions. Do not extend that qualification to COLI9500H or COLI9510 by association.

Turn a shortlist into a treatment recommendation

For an initial review, send Cestoil the fuel type, untreated HFRR result if available, target requirement, lowest handling temperature, other additives used, and expected treatment volume. If some information is unavailable, identify what is known and which points need evaluation.

Request a sample for a fuel-specific comparison, or discuss product selection, dosage, and a quotation with Cestoil. The aim is to select a Northshore grade with supporting test results, workable handling conditions, and a clear treatment cost for your application.

Source: Cestoil Northshore Diesel Lubricity Improver Portfolio, 2026 (PDF), pages 2 and 5–9. Product selection guidance and reported examples are drawn from this brochure; request the current product and supporting test documentation for your evaluation.