Fleet Managers’ Guide to Oil Analysis: Predict & Prevent Equipment Failures

07 Aug 2025

Oil analysis offers powerful insights into the condition of your oil, components and your equipment's overall health. With this knowledge, fleet managers can better manage predictive maintenance and save money on equipment failures in the long run.

In this blog, we’ll help you understand how oil analysis fits into your predictive maintenance strategy and leads to fewer equipment failures and a reduction in costs.

What is oil analysis and why does it matter?

Oil analysis involves chemically analysing a sample of the oil to determine its condition. It can reveal problems like microscopic metal, contamination, oil viscosity, oxidation and total base number (TBN), amongst other things. 

Understanding the condition of your oil brings several benefits, including:

• Identifying early signs of component wear
• Reducing costly breakdowns
• Optimising oil change intervals

Routine engine oil analysis helps you catch small issues before they become major failures—minimising downtime, reducing repair costs, and extending the life of your fleet.

How oil analysis detects problems and protects your equipment

If you’re experiencing equipment failures or component corrosion, you may benefit from introducing oil analysis. That way, you can identify issues early on and reduce downtime and costly repairs with preventative maintenance.

1. Sampling process

An oil sample is taken from a pressurised line before the filter, the dipstick or a drain port. It should be collected while the equipment is at operating temperature and stored in a clean sampling bottle, free from contaminants, and then sent to a lab for thorough testing.

2. Key test metrics

Oil analysis tests for viscosity, water content, particle count, additive depletion and contamination. These metrics can indicate issues such as engine wear or leaks and indicate whether the oil needs to be changed.

3. Interpreting lab results

Once you receive the lab results, understanding what they mean is key to making improvements and protecting your machinery.

Viscosity

If the viscosity is more or less than 10% of the original grade, the oil can not perform its functions properly. This can lead to overheating, accelerated wear and component failure.

Metals

Metal contamination can occur from manufacturing, routine service, faulty seals, open hatches and using the wrong oil. This can cause friction and lead to accelerated wear and corrosion.

Water

Water contamination can lead to rust, corrosion and oxidation which can all damage equipment. It can cause overheating, accelerated wear and lead to component failure.

Contamination

Particles smaller than 2 microns can cause significant damage to your equipment. This could include water, metal, dust, sand and rubber, which all accelerate wear.

Common equipment failures that oil analysis can predict

As well as revealing the condition of the oil itself, the oil analysis results can indicate other issues within your equipment. Here are a few issues that oil analysis can reveal about your equipment

How often should you test an oil sample?

The right oil sampling frequency depends on your equipment, operating environment and the amount of data you have on your fleet’s performance. For heavy-duty machines, like haul trucks, loaders, dozers or excavators, working in demanding environments, oil sampling typically begins around 250 operating hours. This allows you to build a clear trend and detect early signs of wear or contamination.

As your data builds and oil condition trends are well established, some fleets successfully extend sampling and drain intervals. For example, a mining operation working with Fluid Life achieved 750-hour oil drain intervals on haul trucks by implementing a structured oil analysis programme and making data-driven decisions.

By comparison, highway fleets or lighter-duty machinery often align oil sampling with standard oil change schedules, unless they’re operating in harsh conditions or using extended drains.

Oil analysis gives you the confidence to optimise maintenance intervals, reduce costs and extend equipment life. Gulf CARE offers expert oil analysis and predictive maintenance support in select markets. Please contact your local Gulf representative to learn how Gulf CARE can help protect your fleet.

Oil analysis checklist: Best practices for fleet managers

Small changes can make a huge difference and routine maintenance, like oil sampling and analysis, can prevent equipment failures and downtime. Here are a few simple steps you can follow to maintain your fleet with oil analysis:

1. Set up a regular testing program

Whether it’s every 2 weeks or 3 months, introduce regular testing to stay on top of your oil’s condition.

2. Train staff on proper sampling methods

The more staff members are properly trained on taking samples, you can rely on accurate testing by ensuring samples are taken regularly and correctly.

3. Partner with a trusted oil supplier/lab

By partnering with a lab or oil supplier, you can rely on high-quality testing, products and accurate results every time.

4. Use results to make informed maintenance decisions

Results may reveal contaminants that lead to corrosion so you can perform oil changes sooner to prevent component wear and equipment failures.

Regular oil analysis supports predictive and data-backed maintenance, like Gulf CARE, which can prevent component damage and equipment failure. By analysing and replacing oil when needed, you can ensure better equipment long-term performance and lower operating costs as the need for repairs will be minimised. 

Learn more about how you could optimise your fleet’s performance by downloading this whitepaper.