How to Judge the Deterioration of Tire Oil

How to Judge the Deterioration of Tire Oil

The deterioration of tire oil can be determined by two methods: visual sensory inspection and key index testing. The former is suitable for on-site rapid screening, while the latter serves as the basis for accurate judgment. The core is to focus on the deterioration characteristics of the oil in terms of appearance, state and composition (oxidative gelling, mixing of impurities/water, and component volatilization). The specific methods and deterioration criteria are as follows:

I. Visual Sensory Inspection (Rapid screening, operable on-site)

Check appearance and color

Normal tire oil is a transparent dark brown/black brown liquid with no obvious suspended solids or precipitates.

Deteriorated oil will become turbid and whitish or stratified, with white foam floating on the liquid surface and dark brown colloidal sediment accumulating at the bottom of the tank. A sudden deepening or darkening of the color is also a sign of oxidation or mixing with water/impurities.

Observe fluidity and state

At normal temperature (20~40℃), normal tire oil has good fluidity, can flow evenly down the container wall without wall sticking or caking.

Deteriorated oil will show a sharp increase in viscosity and poor fluidity, with film formation on the wall, stringing when dripping, and even local thickening and caking, which is a sign of performance attenuation caused by oxidative gelling.

Smell the odor

Normal tire oil has a characteristic fishy smell of heavy fuel oil without pungent peculiar smell.

Deteriorated oil will emit sour, burnt or pungent odors, which is a feature of acidic substances produced by oxidative decomposition of the oil, or volatilization of light components and high-temperature carbonization of heavy components.

Inspect for water and impurities

Take a small amount of oil into a transparent test tube and let it stand for 5~10 minutes. Normal oil has no stratification and no sediment at the bottom.

The appearance of oil-water stratification (water droplets/water layer at the bottom) or sand/solid impurities at the bottom indicates that the oil has mixed with water or impurities and deteriorated.

II. Key Index Testing (Accurate judgment, laboratory/professional testing)

If abnormalities are found in sensory inspection, professional testing is required to confirm the indicators. Three core indicators are tested, and any deviation from the standard is judged as deterioration. The specific standards are as follows:

Kinematic viscosity: At the normal temperature of 40℃, the kinematic viscosity of normal tire oil falls within a fixed range (slightly different for products of different processes, refer to the manufacturer's standard). A viscosity increase of ≥20% compared with new oil indicates deterioration due to oxidative gelling, which will cause pipeline blockage and incomplete combustion.

Water and mechanical impurity content: Qualified tire oil has a water content ≤0.5% and mechanical impurity content ≤0.3% (mass fraction). Exceeding either index is judged as deterioration, which will cause equipment corrosion and nozzle blockage.

Acid value: The acid value of normal tire oil is ≤1.0mgKOH/g. When the acid value ≥1.5mgKOH/g, it indicates severe oxidation of the oil with a large amount of acidic substances produced, which will corrode storage tanks, pipelines and combustion equipment.

III. Usage Principles for Deteriorated Tire Oil

Oil that is only slightly turbid, without stratification/sediment, and whose viscosity and acid value meet the standards after testing can be used normally after filtration.

Oil with obvious stratification, gelling, sediment, or exceeding any key index must be purified (filtration, dehydration, degumming) and tested to meet the standards before use.

Severely deteriorated oil (e.g., caking and solidification, strong sour odor, acid value exceeding 3.0mgKOH/g) is strictly prohibited from direct use to avoid serious damage to equipment.

IV. Supplementary Notes

Sensory inspection shall be carried out at normal temperature (20~40℃) to avoid misjudgment of deterioration caused by a sharp increase in oil viscosity at low temperatures. For oil stored for more than 6 months, index testing is recommended before use even if there is no abnormal sensory performance to ensure safe use.