Why Used Engine Oil Must Not Be Used for Tire Mounting
Mounting a tire on a rim requires reducing friction between the tire bead and the rim. Engine oil, used oil, grease, and other petroleum products are sometimes used for this purpose. Although these substances make the tire easier to mount, this practice violates manufacturers' requirements and creates a risk of tire damage.
A proper tire mounting lubricant should facilitate mounting and bead seating, then dry. Used engine oil does not dry, continues to provide lubrication, and may affect the rubber components of the wheel assembly.
The Risks of Using Used Engine Oil
1. Effects on Rubber
Tire manufacturers explicitly prohibit the use of petroleum-based lubricants for tire mounting.
Michelin specifies that only approved tire mounting lubricants should be used. Petroleum-based products, silicone, gasoline, ether, and antifreeze must not be used. Similar requirements appear in the instructions issued by Continental and other manufacturers.
Contact with petroleum products can alter the properties of the rubber in the tire bead, inner tube, and rim flap. The potential effects depend on the rubber compound, the amount of oil, and the duration of contact. Damage may not become apparent immediately, so the absence of visible defects after mounting does not confirm that this method is safe.
2. Tire Slippage on the Rim
Specialized tire mounting paste provides the temporary lubrication needed during installation. Once dry, it should not leave a lubricating film.
Used engine oil continues to act as a lubricant. During acceleration, braking, or the transmission of high torque, the tire may slip relative to the rim.
The risk is particularly high in the following applications and conditions:
- Truck and off-road tires
- Agricultural machinery
- Large off-the-road (OTR) tires
- Operation at reduced tire pressures
- Powerful cars and motorcycles
Titan explicitly warns that residual lubricant can cause the tire to slip on the rim.
3. Damage to Inner Tubes
On wheels fitted with inner tubes, tire slippage creates an additional hazard. The inner tube may move with the tire while its valve stem remains held in place at the valve hole in the rim.
Possible consequences include:
- Valve stem misalignment
- Tearing of the inner tube around the valve stem base
- The valve stem being torn off
- Rapid loss of tire pressure
Oil may also affect the material of the inner tube and rim flap.
4. Improper Bead Seating
Tire mounting lubricant does more than make installation easier. It helps the bead seat evenly on the rim and reduces the risk of damage from mounting tools.
An unsuitable product, excessive lubricant, or contamination can contribute to:
- Uneven bead seating
- Tire movement relative to the rim
- Wheel imbalance
- Bead damage
- Air leakage through a contaminated sealing area
Michelin states that proper lubrication promotes concentric tire seating and reduces the risk of bead damage.
5. Contaminants in Used Engine Oil
The composition of used engine oil cannot be verified without laboratory analysis. It may contain:
- Soot and combustion byproducts
- Metal particles
- Sand and dirt
- Residual fuel
- Water and other operating fluids
Michelin requires tire mounting lubricant to be kept clean and free of sand, metal shavings, and other solid particles. In tires fitted with inner tubes, these contaminants can abrade the tube and eventually cause it to rupture.
6. Health Risks for Tire Technicians
Used engine oil is not intended for regular skin contact. The UK's Health and Safety Executive (HSE) warns that frequent and prolonged contact can cause dermatitis and other skin disorders, including skin cancer.
Using used engine oil for tire mounting exposes employees to additional and entirely unnecessary contact with a harmful substance.
What Should Be Used
Only specialized tire mounting pastes or liquids that meet the requirements of the tire and wheel manufacturers should be used.
A suitable tire mounting lubricant should be:
- Compatible with rubber
- Nonflammable
- Quick-drying
- Free of any residual lubricating film once dry
- Noncorrosive to the rim
- Clean and protected from contamination
- Used at the recommended concentration
The following must not be used as substitutes for tire mounting lubricant:
- Used or fresh engine oil
- Solidol and other lubricating greases
- Diesel fuel
- Gasoline and solvents
- Antifreeze
- Silicone lubricants
- Household chemicals of unknown composition
If a Tire Has Already Been Mounted Using Oil
Visible oily residue can indicate the presence of an oily substance, but it cannot reliably establish its chemical composition. To determine what was used, ask the tire service provider for the product name and its safety data sheet (SDS).
If the use of oil is confirmed, or the substance cannot be identified, the following steps are recommended:
- Demount the tire
- Clean the rim and tire bead using a cleaning agent approved by the manufacturer
- Inspect the condition of the tire bead
- Inspect the inner tube, rim flap, valve, and sealing components
- Remount the tire using a specialized tire mounting lubricant
- Check that the beads are correctly seated and balance the wheel
A tire should not automatically be discarded solely because of brief contact with oil. The decision should be made after demounting and inspection. If the rubber shows softening, swelling, cracking, or other changes, the tire must be referred to the manufacturer's technical specialist for assessment.
Conclusion
Used engine oil makes mounting easier during installation, but leaves a petroleum-based film of uncontrolled composition between the tire and the rim. It may affect the rubber, contribute to tire slippage, damage the inner tube, and contain solid contaminants.
Any savings on specialized tire mounting paste are negligible compared with the cost of a damaged tire, repeat repairs, or the consequences of a sudden loss of tire pressure.
Using used engine oil for tire mounting is technically unsound and unsafe.
Sources
- Michelin: Lubricant for Michelin Truck Tires
- Continental: Tire Mounting Safety Instruction
- Titan OTR Tires: Safety Information
- Trelleborg Tires: Tire Maintenance
- UK HSE: Used Engine Oil