Romsey Motor Factors Ltd
Greatbridge Business Park,
Unit 4, Budds Lane,
Romsey, Hampshire,
SO51 0HA

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motor oil


Find out exactly what motor oil viscosity is best for your driving conditions and why running the right oil viscosity is important. In order for motor oil to provide lubrication, its viscosity must hold up under your engine's extreme temperature conditions.
Oil thins when heated and thickens when cooled. Choosing the proper motor oil viscosity grade for the ambient temperature of your geographic location is therefore vitally important.
In a monograde oil the motor oil viscosity is defined at only one temperature, either high or low. A multigrade must keep a viscosity that will protect the engine effectively at both high and low temperatures.

This makes multigrades an easy and popular year-round choice for drivers who experience hot summers and harsh winters. Multigrades are easily recognized by the dual viscosity rating (i.e. 10W-30 where the 10W is the low temperature or winter designation and the 30 is the high temperature designation). It is the motor oil viscosity modifier additive that produces a thickening effect at high temperatures but is dormant at low temperatures.

Which viscosity grade is right for you?
SAE Viscosity Grade Motor Oil: 5W-30
Temperature Conditions: Below 0° F
Description: Provides excellent fuel economy and low temperature performance in most late-model automobiles. Especially recommended for new cars.
SAE Viscosity Grade Motor Oil: 10W-30
Temperature Conditions: Above 0° F
Description: Most frequently recommended motor oil viscosity grade for most automobile engines, including high-performance multivalve engines and turbo-charged engines.
SAE Viscosity Grade Motor Oil: 10W-40
Temperature Conditions: Above 0° F
Description: The first multigrade introduced. A good choice for controlling engine wear and preventing oil breakdown from oxidation. Note: Always check your owner's manual or warranty requirements before using this grade.
SAE Viscosity Grade Motor Oil: 20W-50
Temperature Conditions: Above 20° F
Description: Provides maximum protection for high-performance, high-RPM racing engines. Excellent choice for high temperature and heavy loads such as driving in the desert or towing a trailer at high speeds for long periods of time.
SAE Viscosity Grade Motor Oil: SAE 30 & SAE 40
Temperature Conditions: Above 40° F & Above 60° F
Description: For cars and light trucks, where recommended by manufacturers. Not recommended when cold-temperature starting is required.

Note: It is important to consult your vehicle handbook to establish the correct grade for your car and environment.