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Oil Analysis Sample Log Worksheet

Oil analysis labs email you PDFs, but nobody trends PDFs. This worksheet gives you one editable table where every sample for every asset sits next to the new oil baseline, so a drift in viscosity or a rising iron count is visible at once.

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Sample date	Asset	Oil grade	New oil viscosity at 40C (cSt)	Sample viscosity at 40C (cSt)	Viscosity change	Water (ppm)	Iron (ppm)	ISO 4406 code	Action
					3.6%
					-4.1%
					14%
					4.7%
					1.2%

Average viscosity change

3.9%

Highest water

520

Highest iron

Limits depend on the oil, the machine and your lab. A change of about 10% in viscosity is a common trigger for investigation, and water limits are tighter for hydraulic and turbine systems. Use your lab report limits and OEM guidance rather than the example rows.

Turn oil analysis results into work orders

Optional review of how lab results could create notifications in your ERP automatically.

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How to use the worksheet

Add one row per sample. Enter the new oil viscosity from the product data sheet and the sample viscosity from the lab. The viscosity change column is calculated for you. Add water, iron and the ISO cleanliness code straight off the report, choose an action, and export to Excel to sort by asset or filter by action. Keep the file as your working register and file the lab PDFs alongside it.

Use the same asset names as your CMMS equipment list
Always take samples from the same port at the same operating state
Log the oil top-ups elsewhere so viscosity changes are explainable

What the numbers tell you

Viscosity change is calculated as sample minus new oil, divided by new oil. A rise usually means oxidation, evaporation of light fractions or contamination with a heavier oil. A fall points to fuel dilution, shear of polymer additives or mixing with a thinner product. Water in ppm shows seal or breather problems. Iron suggests wear of gears, shafts or cylinders. The ISO 4406 code reports particle counts at three sizes and shows how clean the system is.

Setting limits

Start with the lab limits and the machine OEM, then tighten as you build history. Many reliability programs set a caution and a critical value per test and use the Action column to record what was done. Trend direction matters as much as the level: iron that doubles in two samples deserves a look even if it is under the printed limit.

Common mistakes

Common errors include sampling right after an oil change, mixing sample points, ignoring contamination codes because viscosity looks fine, and letting reports pile up with no action recorded. Another is comparing the sample viscosity with the wrong baseline grade. Put the correct new oil values in every row.

Frequently Asked Questions

Do I need a lab to use this worksheet?

The log works with any source of results: a commercial lab, an in-house viscometer or a patch test kit. You only need to fill the columns you have. Blank cells for water or iron do not break the calculation of viscosity change.

What viscosity change should trigger action?

There is no universal number. Many programs investigate when viscosity shifts by about 10% from new oil and treat 20% as critical for most industrial oils. Check your lab and OEM guidance for the specific machine.

Can I add more columns?

Export to Excel and add columns such as TAN, additive elements or sample interval. The online table keeps the common fields so it stays quick to fill on a phone or tablet.

How often should I sample?

Critical gearboxes and turbines are often sampled monthly or quarterly, general hydraulics quarterly or every six months. Shorten the interval when a trend moves.

Netray can help pull oil analysis results into your ERP maintenance module so action items become work orders rather than spreadsheet rows.

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