15w 40 engine oil from leading oil manufacturers such as Carlube and Castrol alongside a budget option. We categorise our oil by grade to make it easier for you to find the correct product for your vehicle. The 15w 40 rating refers to the viscosity of the oil at cold temperatures (when starting the car) and while running. This system is used by the manufacturer of the vehicle to ensure that the moving parts of your engine are getting the right amount of lubrication at both times, so it is vital to follow the manufacturer's recommendation. You can find this in your handbook or use the Parts Finder app in the Car Parts section of our site. All brands of engine oil we stock meet the latest API and ACEA requirements, so you can be sure it ticks all the right boxes on quality. To achieve this standard, high quality base engine oils are blended with advanced technology additives to give high anti wear and detergency properties in all mineral, semi synthetic & fully synthetic motor oils.