THE SAE J 300 GRADE AND HOW TO FIND THE RIGHT ENGINE OIL

How does the manufacturer choose the SAE grade? Can I choose whatever oil I like for my car? Total clears the matter up.

You have already heard of oil viscosity and the SAE J 300 grade. We explained what these were so that you can be sure that the engine oil you are buying is suited to your vehicle. However, you might still be unsure about this area, for example how to choose the oil manufacturer or whether you can use another SAE grade instead of the one recommended by the manufacturer. In this section we will try to shed some light on these questions.

How does the manufacturer choose the SAE grade?

The first thing you need to know when selecting an oil is that the SAE grade for each type of engine depends on several basic factors, such as: the design of the engine and what the manufacturer was aiming to achieve, for example did they design the engine to save fuel or increase its useful life.

Reducing fuel consumption and creating long-lasting engines are two fairly common objectives in this day and age. Manufacturers are inclined to make smaller engines, with three cylinders, which are capable of delivering similar or improved power and performance, but which need less fuel and therefore comply with emissions standards. This means that engine oils need to be increasingly fluid.

More and more of the latest American and Japanese cars use SAE 0W-20 and 5W-20 oils with gasoline engines and in Japan, they are even starting to use SAE 0W-16 oils.

As for Europe, the SAE oil that has risen in popularity over the past few years, both for gasoline and diesel engines, is the 5W-30 grade. In addition, the European Automobile Manufacturers' Association (ACEA), is expected to publish new recommendations this year and to introduce the ACEA C5 category, which will see a change in viscosity limits. This means that 5W-20 and 0W-20 lubricants will be authorized for use in gasoline and diesel engines manufactured in Europe, regardless of whether they are fitted with particulate filters. It is also hoped that European manufacturers will introduce standards this year recommending xxW-20 engine oils.

In the case of heavy vehicle manufacturers, the trend points towards xW-30 lubricants. Although some field tests have been carried out on xxW-20 oils, for the moment SAE xxW-30 oils remain the most recommended when it comes to saving fuel. As for API, they have implemented standards for this type of vehicle that approve 5W-30 and 10W-30products.

Can you use a different SAE oil than the one recommended by the manufacturer?

Up until now, it has been common practice to use oil with a different viscosity than that recommended by the manufacturer. For example, while in northern European countries the more fluid 5W-30 and 0W-30 oils are used to make it easier to start vehicles in the cold, in southern Europe, where temperatures are never as low, 10W-40 and 5W-40 oils are more commonly used. People tend to forget that, the easier it is to start your car, the less wear your engine suffers.

Another example: if you have problems relating to wear in the cylinder area and a loss of pressure in the piston, it is usually recommended to use SAE 20W-50. If your car is consuming a lot of 5W-30 lubricant, it can be replaced by a 5W-40 lubricant, which has a higher viscosity, will reduce wear and allow for better compression in the combustion chamber. This is recommended only when there is a problem.

Up until now, engines could allow for these changes thanks to backlash. However, you have to be very careful with modern-day engines as they are much smaller. Using a 5W-40 oil with modern-day engines may result in trouble penetrating the bearing because of its viscosity and minimum backlash, which can lead to faster wear. The same occurs with the piston and liner areas. 5W-40 oil can have difficulty flowing into and out of these areas, meaning it deteriorates rapidly and causes wear and poor combustion, among other problems.

This is why it is so important to strictly follow the car manufacturer’s recommendations, particularly where new cars are concerned. You must also remember that new oils cannot be used in old engines with a lot of backlash, as this would considerably increase the consumption of lubricant and may cause wear.

Don’t forget:

The SAE rating tells us the way oil flows to create the lube film in the engine parts. Always choose it based on the engine’s design and the manufacturer’s recommendations.

Emission restriction standards have led to even more fluid lubricants, which can help save fuel provided they are compatible for use with your engine.

API, ILSAC, ACEA, JASO and manufacturers’ standards take the environment in which the lubricant is used into consideration, for example at high temperatures or in the presence of contaminants. As such, they perform tests which take into account the SAE and the benefits of the bases and additives best suited to protect the engine so that its useful life is as long as possible. They also calculate the potential fuel savings that the product can provide.

As you can see, the engine oil that your vehicle uses is the result of a lot of tests, standards and recommendations which make it the best choice to maintain your engine. That is why you must always use high-quality lubricants adapted to the design of your engine.