Oil Resistance — ISO 1817 / ASTM D471 / IRM Reference Oils · Rubber Testing

What Is Oil Resistance?

Oil resistance test is performed by keeping the sample in standard reference oil (such as IRM 901/902/903) at a defined temperature and time; It is an experiment in which volume, mass, hardness and mechanical property changes are measured.

Purpose of Oil Resistance

The aim is to verify that swelling and loss of properties of the elastomer in contact with oil remain within specification limits.

Which Products Is Oil Resistance Applied To?

Engine and transmission gaskets
Hydraulic hose and seals
Oil seals and O-rings
Compressor elastomers

In Which Sectors Is Oil Resistance Used?

RubberAutomotiveMachinery

Standards Related to Oil Resistance

ISO 1817
ASTM D471
ASTM D5964 (IRM reference oils)
ISO 23529

Oil Resistance Conditions

Reference oil: IRM reference oils or service oil as defined in the standard
Temperature: Defined in the specification; represents the service temperature
Time: Defined in the standard; typically 70 or 168 hours
measured change: Volume and mass change, hardness change, tensile properties

Equipment for Oil Resistance

Closed dip pots and temperature-controlled oven/bath
Analytical balance and volume measurement setup
Durometer and tensile tester
Reference oil stock

Sample Requirements for Oil Resistance

Initial measurements should be recorded
Oil type and batch information must be documented
The sample surface must be cleaned as defined in the standard.
The number of specimens is defined in the standard

Duration of Oil Resistance

1–2 weeks depending on duration.

Oil Resistance Procedure

1Samples are measured and weighed.
2The reference oil is brought to temperature.
3Samples are immersed for a defined period of time.
4The samples are removed and the surface is cleaned.
5Volume, mass and hardness are measured.
6Mechanical properties are measured and the change is calculated.

Oil Resistance Acceptance Criteria

The acceptance criteria are the maximum volume change and property loss limits given in the specification.

Evaluation of Results

Different reference oils (IRM 901, 902, 903) have different aniline points and affect swelling to a different extent; results cannot be compared without specifying oil. Additives in actual service oil may behave differently than the reference oil.

Oil Resistance Report

Applied standard and reference oil
Temperature and duration
Before/after measurements
Volume and mass change
Mechanical property change

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Automotive and industrial sealing specifications

Rubber Testing — What Does This Testing Field Cover?

The section below describes the field that the Oil Resistance test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Rubber testing determines the mechanical behaviour of an elastomer and its resistance to environmental effects. Elastomers are assessed with a different logic from metals and plastics: the real question is not strength but ELASTIC RECOVERY and ageing behaviour.

The function of an elastomer is usually to deform and return: a gasket is compressed and provides a seal, a mount absorbs vibration, a hose expands under pressure. What is measured in the field is therefore not "how many newtons does it withstand" but "how far does it recover after deformation, and how long does it keep doing so".

COMPRESSION SET is therefore the most decisive measurement in the field. If a gasket cannot recover after being held compressed for a long period, it has lost its sealing function even though it has not torn at all. This measurement is made together with temperature, because permanent set increases rapidly with temperature.

Hardness is the most common measurement in the field, using the Shore A and IRHD scales. It is fast and practical but does not define the material on its own: two different compounds of the same hardness can show completely different ageing and fluid resistance. Hardness is valuable in monitoring compound consistency.

On the environmental resistance side, hot air ageing, swelling in fluids, ozone cracking and low temperature behaviour are examined. FLUID RESISTANCE is particularly critical: the same elastomer behaves differently in fuel, oil, coolant and brake fluid — swelling in one, shrinking in another, hardening in a third. The material is therefore tested with the actual fluid it will contact and at the actual temperature.

Ozone cracking is a silent cause of failure in parts used outdoors. Low concentrations of ozone in the atmosphere create surface cracks in unsaturated elastomers under strain; the part cracks while appearing to carry no load at all. An ozone chamber accelerates and reveals this behaviour.

Low temperature behaviour is the second silent risk. As an elastomer approaches its glass transition temperature it loses elasticity and behaves like a rigid plastic; a gasket starts to leak in the cold. Low temperature recovery and brittleness tests establish this limit.

A change of compound is not a silent change in this family. When filler content, plasticiser or the vulcanisation system changes, mechanical properties and fluid resistance shift together; verification is repeated.

Method groups in this field

Mechanical
Tensile stress-strain properties, tear strength, abrasion (rotating drum and Pico), fatigue and tear propagation.
Hardness
Shore A and IRHD indentation hardness; a rapid indicator of compound consistency.
Permanent deformation
Compression set and stress relaxation; decisive for sealing components.
Fluid resistance
Swelling in fuel, oil, coolant and chemicals, change in mass and volume, loss of hardness and strength.
Ageing
Hot air ageing, ozone cracking, the effects of UV and humidity.
Low temperature
Low temperature recovery, brittleness temperature and flexibility measurements.

Commonly confused in this field

Hardness does not define the material; two compounds of the same hardness can show different ageing and fluid resistance.
Fluid resistance must be tested with the actual fluid and the actual temperature; a general claim of oil resistance is insufficient.
Without measuring compression set, no decision can be made about sealing life.
Ozone cracking occurs under strain; a test with an unstrained specimen does not show the real risk.
A change of compound requires verification to be repeated; a supplier may change its compound silently.
A gasket whose low temperature behaviour is not stated produces unexpected leaks in cold climates.

Which decisions these results support

Material selection for gaskets and sealing components
Automotive and industrial component approval
Verification of a compound change
Root cause analysis of field leaks and cracking
Declaration of the operating temperature range and fluid compatibility

Related Tests

Frequently Asked Questions About Oil Resistance

According to which standard is Oil Resistance made?

Oil Resistance is executed in scope ISO 1817, ASTM D471, ASTM D5964 (IRM reference oils) and ISO 23529. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does Oil Resistance apply to?

Mainly applied to Engine and transmission gaskets, Hydraulic hose and seals, Oil seals and O-rings and Compressor elastomers. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is Oil Resistance done?

The determining parameters are: Reference oil — IRM reference oils or service oil as defined in the standard, Temperature — Defined in the specification; represents the service temperature and Time — Defined in the standard; typically 70 or 168 hours. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for Oil Resistance?

Initial measurements should be recorded, Oil type and batch information must be documented and The sample surface must be cleaned as defined in the standard.. The number of samples is determined according to the product standard and the scope to be reported.

How long does Oil Resistance take?

1–2 weeks depending on duration. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the Oil Resistance result called "appropriate"?

The acceptance criteria are the maximum volume change and property loss limits given in the specification.