Tightness and an E10 transition: how to define a baseline
A prior evaluation can document condition, but any repeat and its timing should follow scope, manufacturer guidance and evidence—not a universal rule.
Head of Operations

In this article
- 01What a baseline documents
- 02Compatibility before loading
- 03When to consider another evaluation
- 04What a test does not prove
- 05Regulatory status
- 06What belongs in the baseline
- 07Controlling the product change
- 08When to compare again
- 09Frequently asked questions
- 10Application record: before-and-after comparison
A baseline before changing product can help separate existing conditions from later findings. That does not mean every station needs exactly two tests or that a universal repeat interval exists.
What a baseline documents
Tank and line identification, product, level, history, alarms, observed water, recent interventions, method, scope and result. Its value is the ability to compare equivalent evidence, not automatically attributing a later finding to ethanol.
Compatibility before loading
The review should include every component that will contact the blend. Compatibility is confirmed by model, product, configuration and manufacturer documentation. Brand or year alone does not support a conclusion.
When to consider another evaluation
The decision may depend on manufacturer instructions, completed changes, alarms, water, operational differences, earlier results or procedure requirements. The interval should be justified in the facility technical plan.
What a test does not prove
An earlier result does not guarantee future performance or establish the cause of a new finding by itself. For MESA 2-D, the independent listing describes a nonvolumetric method and its conditions; evaluated performance should not be turned into a volume reading for every test.
Regulatory status
The planned implementation was suspended by Resolution MIPRE-2026-0010986 and the previous schedule was voided. As of September 4, 2026, no new active date was located. Any plan should recheck that status before investments are made.
What belongs in the baseline
Record identified tanks and lines, current product, level, recent delivery history, observed water, alarms, inventory differences, repairs and assessment method. Attach the original report instead of reducing it to “everything was fine.” If a line or containment component was excluded, that exclusion must accompany every later comparison.
The independent MESA 2-D listing explains the method’s conditions. Its results do not certify future behavior with another product or replace compatibility verification.
Controlling the product change
Before receiving a different blend, confirm the wetted path, containment condition, ability to identify water, delivery procedures, labeling and response to off-specification product. Retain samples or data when required by the quality plan. Our article on phase separation explains why water, temperature and handling matter.
When to compare again
There is no universal “before and after” frequency. Define triggers: actual product change, intervention in an assessed component, persistent alarm, water ingress, unexplained difference or a procedure requirement. When repeating an assessment, use the same asset inventory and document differences in method and conditions; otherwise, results are not directly comparable.
Panama’s prior schedule was suspended by Resolution MIPRE-2026-0010986. Review official status before setting milestones and use the E10 adaptation guide to organize the file.
Frequently asked questions
Does a pre-change test prove E10 compatibility?
No. It assesses tightness within a scope and conditions; compatibility is confirmed by component and documentation.
Must the exact same method be used afterward?
A consistent scope improves comparison, but the method must remain technically applicable and be documented.
What if water appears after the change?
Protect operations under the site procedure, confirm the observation and investigate water ingress and fuel quality separately.
Application record: before-and-after comparison
Before applying this guide to a facility, identify the same tanks, lines, products, levels and scopes. Write the decision as a verifiable question: what actually changed and whether the assessments are comparable. A recommendation without an asset, question and date is difficult to audit and may continue circulating after the facility has changed.
- Input: baseline, change control, later report and stated differences.
- Source: retain the title, issuer, edition or date, link and section used.
- Owner: assign who confirms data, who authorizes action and who verifies closeout.
- Status: use confirmed, pending, not applicable or out of scope; do not fill evidence gaps by assumption.
Retain the version that supported the decision and record differences between the plan and field conditions. If the product is introduced, an asset is repaired or a new indication appears, reopen the record instead of reusing the earlier conclusion. This keeps the article a working framework rather than a substitute for the manual, design, risk assessment or responsible authority.
Continue learning in Master University. To review a real case, share the inventory, legible photographs, objective and available documents through our contact page; a responsible technical recommendation begins with scope.