Oil Sample Testing - How it works

How to buy a test kit

How to take a sample

How to identify a sample

How to send a sample to the lab

How to receive a sample report

How to read a sample report

How to view data online

How to buy a test kit

Terra Analytical lab uses a prepaid test kit system which means we can start testing as soon as we receive your samples.  The initial cost of the test kit covers the sample bottle and label, FreePost outer mailing canister, testing and reporting of the results.

Most sample tests are covered by a standard oil test kit which can also be used for coolant or grease (not fuel).

We have a range of specialty test kits for specific applications.  Additional tests and Urgent options are available for an additional fee if necessary.  Please contact the lab to discuss options.

Test kits are available from Terra Cat Parts or TWL branches throughout New Zealand (refer to Order Test Kit for phone orders or Find A Branch if you need a test kit as soon as possible).

How to take a sample 

Fluid samples should be taken by suitably trained or supervised service technicians.  There can be dangers associated with hot fluids, high pressures, electrical hazards etc.  It is important to correctly identify the compartment and that the sample is taken at the right time and place, with the right tools and in the right conditions.  Refer to further information on taking a sample under Resources.  

Note that differing results can be obtained by sampling at different points in the system.  The preferred option is to use live sample valves fitted at points in the system recommended by the equipment maker.  These allow samples of hot oil to be taken from a working system and provide the best indication of the working fluid.

Whether sampling with a pump or from a drain plug when the oil is being changed we recommend a "midstream" sample.  The oil that comes out first (or last) may contain metal or debris that can give a disproportionate representation of the bulk of oil in the system.     

If samples are taken from a dipstick tube or (worse) from an oil filter housing this can result in misleading sample results due to the abnormal concentration of debris. 

There is a degree of skill required to take a good sample and there can be unnecessary confusion and expense if samples are mixed up or contaminated.  We recommend that the sample taker be included in feedback on the success of the sampling.  

How to identify a sample

The lab processes hundreds of samples each day and the database contains thousands of items of equipment with multiple compartments.  Unique identification of samples is very important and raises some challenges.  Ideally, all samples from the same equipment compartment should be named exactly the same each time as this allows a sample history to build up in one place for easy viewing.  If an equipment compartment is named differently each time it is possible for the data to get fragmented.

Some terms used by the lab:

Customer The term Customer Account is used for reporting purposes.  Large companies may have multiple Customer accounts.  
Equipment Serial Number >This is the unique alphanumeric name that identifies a piece of equipment.  Often this is a literal serial number but it does not have to be - e.g. a Registration Number for a truck.
Equipment Unit Number This is a supporting alphanumeric name that may be more useful to people who may not be familiar with literal serial numbers.  Could be a Fleet Number or a commonly used name.
Equipment Compartment The label has some checkboxes for common compartments.  Please take care with multiple compartments such as Front and Rear diffs, Left and Right Final Drives or Port, Stbd and Aux Engines.
Oil Type For full identification, we require the Oil Company/Brand and the full product name.  For example Caterpillar DEO ULS.  Partial or ambiguous names will be registered as Unknown which indicates we cannot identify it.
Oil Grade Most lubricating oils are sold in SAE grades or ISO viscosity grades and grease in NLGI grades.  For factory fill or unknown or mixtures it is best to leave this as unknown to avoid alerts based on guesses. 
Meter This is for an hour meter or odometer that increments over the life of the component.  
Oil Hours This is for the literal hours (or kilometers) of the sampled oil.  Wear metals accumulate over the life of oil so this information affects the interpretation of the results.
Oil Added This is for the amount of top-up oil that was added to the compartment in the interval since the last sample.  It represents oil being lost or burnt and not the system capacity.
Oil Changed This checkbox is to indicate whether the oil was changed immediately after the sample was taken.  This can avoid alerts to change oil if we know it has already been changed.
Filter Changed This checkbox is to indicate whether the filter was changed immediately after the sample was taken.  This can avoid alerts to check the filter if we know it has already been changed.
User Any person who wants access to their records in the database is given a User ID and Password.  An email address and phone number are required.
Contact A Contact is a User who has also been set up to receive sample reports when they are released.  A User does not have to be a Contact and receive reports.  All Contacts must first be set up as a User.


It is very important to fill out the label as completely as possible.  The label is the written contract with the lab that identifies the owner of the sample, the type of fluid and equipment (which determines the type of testing that will be done)  and other relevant details. 

The online Oil Commander Database has a feature for creating labels which makes this easier to manage and can eliminate errors - please contact the lab to learn more about this.      


How to send a sample to the lab

Samples are sent to the lab in Christchurch using the NZ FreePost outer mailing canister - except for fuel samples which are sent via courier.  

The sample bottle should have the lid firmly tightened by hand (not excessively) to avoid leakage.  Any fluid on the outside should be removed as these can cause the label to become unreadable.  

The sample bottle and label should be placed in the outer mailing container.  The NZ Freepost details on the outside ensure that the bottle will be delivered to our Christchurch lab, typically within two days between Islands.  We receive hundreds of these each day and it can be faster than typical courier deliveries.  Check the clearing times of the NZ Post box used as some are cleared more frequently than others.   

Diesel fuel samples or any dangerous goods must not be sent via NZ Post.  We provide a specific Diesel Fuel test kit for diesel fuel. Diesel fuel samples are handled by courier.  It is important that the supplied dangerous goods documentation is completed correctly as there are legal obligations the courier must comply with.  Keep the courier ticket label for tracing if required.

How to receive a sample report

Email reports are sent out once the oil sample testing is complete and the sample results have been reviewed and evaluated by an Interpreter.  The email reports also have a PDF attachment which can be printed or sent to interested parties.

Some fleet managers may receive dozens of reports in a day and for this reason, we have a daily summary report that presents a short version of all reports for that day.  This allows an action to be initiated as fast as possible.  The individual Full Details reports may arrive an hour or so later as it takes longer to process all the pdf attachments.   

The email reports are sent to all the Contacts in the database that have been set up for the specific Customer account that the sample is assigned to.  There are often multiple Contacts set up for each Customer.  Contacts are Users who have been set up in the database specifically to receive these email reports.

Users and Contact details are usually set up in the database based on incoming label information.  If relying on third parties to send in samples and complete labels it may be wise to contact the lab to ensure that your User and Contact details are set up correctly and to query who is receiving email reports.  If you have staff changes it may also be wise to check that the Contact list is up to date,  

Sample reports are typically released within 2 working days of physical receipt of the sample.  If it takes much longer we recommend that you contact the lab as there may be an identification problem. We sometimes receive sample bottles with no labels and we attempt to identify the sender where possible.  


How to read a sample report

When you receive an email report we recommend that you check that you can identify the Equipment and know that this is in your area of responsibility.  If you believe you have received a report in error we recommend that you contact the lab to find out why you received this as it may be time to review your User setup.   There may be other Contacts who may have received the same report.  We understand that there are many ways to operate businesses and the database is flexible to allow options.  For large businesses there can be challenges in ensuring that the right people get the right reports for their area of responsibility.  It may be necessary to create new Customer accounts or new Job Sites or to move or merge Equipment around - let us know if we can help simplify this.

Sample reports can be used at a high level to prioritize work by simply looking at the Evaluation Code.  These evaluation codes are best thought of as a priority coding system for any Action that needs to be taken.  They are not an overall assessment of the health of the equipment compartment.  For example, a compartment may have suffered serious wear in the past, but the current oil sample may be good, indicating there is no abnormal wear taking place during the sampled interval.  They should also not be considered an overall evaluation of the condition of the oil.  For example, oil at the end of a long drain interval may be depleted and not suitable for further use.  But if these results are normal for the hours and label indicates the oil has been changed then no further Action needs to be taken and therefore this sample may receive an A result. 

Evaluation Code Significance
Tick No Action Required

Monitor Component - Borderline or we wish to Bring something to your attention.  No Action required but continue to sample and read the Comment to see why.

red danger Action Required - Something appears Critical or needs to be Checked or Changed. - we believe some Action is required.  Read the Comment as the Action may not require workshop attention. 
Urgent action Urgent Action Required - Results appear extremely serious and we believe Urgent Action is required to save the equipment or operators from harm (if it is not too late). 


Engineers who need to investigate further may wish to understand the full technical details of the sample report.  Technical data on the report analyses and test methods are available here What It All Means.  


How to view data online

All sample data is stored permanently in the Cat® S•O•S database which is available at all times for Users online via a standard internet browser. 

The website is supported for Google Chrome and Microsoft Internet Explorer browsers and may not display or work correctly with any other.  It also uses popup menus which will not work if a Pop Up Blocker feature is Enabled.  Browsers that also use the Google search bar may have one more Pop Up Blocker to Disable.    

You will require a User ID and Password to be able to log into Cat S•O•S.  These are typically set up based on incoming sample labels.  If you are unsure please contact the lab to find out your User ID and Password.

Email reports have a link that can be clicked on to launch Cat S•O•S.  Once logged in these links will take you directly to the specific sample which can save some time.

It is possible to navigate directly to the database at any time and find the entire sample history for all Equipment that is assigned to the Customer accounts that you have been assigned permission to view.  The login fields are found at the top of the Home page for this website.  


The database has many features and functions.  Further training information is available at Resources.