QUESTION 10.4.2

Lubricating and hydraulic-oil analysis trends

Oil, Chemical, LPG, LNGChief Engineer's Office

What is being checked

The inspector is checking whether representative samples are taken at defined intervals, laboratory trends are interpreted against machinery condition and abnormal results produce timely operational and maintenance action.

Ready onboard

0/6 complete

EQUIPMENT LISTThe programme covers main and auxiliary engines, stern tube, gear, compressors and critical hydraulic systems as applicable.SAMPLE QUALITYSamples are taken warm, under representative service conditions, from the correct point using clean labelled containers.INTERVALSampling frequency follows maker, company and class requirements, including stern-tube obligations.TREND REVIEWViscosity, water, fuel dilution, acidity, base number, wear metals, particles and contamination are trended as relevant.ACTIONCaution or critical reports trigger resampling, purification, inspection, load restriction, oil change or repair under technical advice.TRACEABILITYReports identify machinery, oil grade, hours, oil additions and maintenance events so trends remain meaningful.

Practice questions

Answer aloud, then open the preparation point.

1Why must the sample be taken under service conditions?

A stagnant, cold or drain sample may not represent circulating oil and can distort water, wear-metal and contamination results.

2Show the last abnormal report and action.

Trace the parameter, technical assessment, immediate control, confirmatory sample or inspection and verified return to acceptable condition.

3What can dilute a wear-metal trend?

Large oil additions or changes, wrong sample point, inconsistent timing and unrecorded maintenance can make the apparent trend misleading.

4Which stern-tube parameters are important?

Follow the class programme, normally including water, chloride, bearing metals and oil ageing at the prescribed interval.

5Can a normal report replace machinery inspection?

No. Analysis is condition evidence that must be considered with temperatures, vibration, filters, leakage and operating history.

Where an observation may arise

MISSED SAMPLE

A required machine or interval is omitted.

POOR SAMPLE

The location, condition or container makes the result unrepresentative.

NO ACTION

A caution or critical result has no documented technical response.

TREND BROKEN

Oil changes or additions are not recorded, invalidating comparison.

REPORT UNKNOWN

Responsible engineers cannot explain the latest result or limits.

Past observations for practice

Process

The PMS indicated 2 overdue jobs (18/02024 and 28/02/2024). The oil samples were not offloaded ashore for laboratory analysis.

Master's practical note

Choose the worst trend, not the latest green report. The value of analysis lies in recognising deterioration early and linking it to the machine's actual behaviour.

Equipment boundary and references

Equipment boundary: Parameters and limits depend on oil type, machinery maker, laboratory method and class programme. Laboratory flags support, but do not replace, engineering judgement and maker limits.

References

OCIMF SIRE 2.0 Question Library Part 2, Version 1.0, Question 10.4.2
IACS UR Z21
IACS Recommendation 36
ISM Code section 10
Machinery and lubricant manufacturer guidance

Last reviewed: 2026-09-10