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Lubricants FAQs

Lubricant FAQs 

What is a lubricating oil? Which is the right one for my engine? How often do I have to change it? These are some of the questions to which you will find an answer in this section

What is a lubricating oil?

In general, it is a substance that reduces friction when placed between two surfaces with relative motion. 

There are lubricants with different grades and viscosities, although their functions have a lot of similarities as they:

  • Reduce friction between two metal surfaces.
  • Protect mechanical components from wear and corrosion.
  • Clean and cool engines.
  • Act as a sealant between the segments/pistons and jackets in order to prevent gas leaks from occurring inside the combustion chamber.

What is the difference between a synthetic lubricant and a mineral lubricant? Is one better than the other?

A lubricant is categorized as synthetic or mineral depending on the method used to obtain the lubricant's main component: the base oil.

When the base oil is obtained through the conventional refining of petroleum, it is considered mineral. When it is obtained through more complex processes (chemical synthesis or other), the lubricant is considered synthetic. 

The origin of the base oil is not indicative of lubricant quality. In other words, a lubricant is no better or worse for being mineral or synthetic. The quality of the compounds is determined by laboratory and engine tests that the lubricant must undergo during the design phase.

Can two lubricants be mixed together in the same engine?

It is not recommended, but if for some reason different oils must be mixed (to fill the tank for instance), it is important to follow certain recommendations.

It is a good idea to use an oil with the same level of quality as the one that is currently being used in the vehicle and, if possible, from the same manufacturer. Additionally, during the next oil change, it is a good idea to replace the oil filter with a new one.

Are there specific lubricants for gasoline and diesel vehicles?

Although many lubricants can be used in both gasoline and diesel vehicles, some lubricants are designed especially for gasoline engines and other ones for diesel engines.

What is the viscosity of a lubricant?

Viscosity is the resistance of a liquid to flow and, in the case of lubricants, it is an essential characteristic to take into account when selecting which is the best product for you.

Vehicle manufacturers are responsible for establishing the most adequate viscosity for their different models, which is included in their manuals. Usually, several viscosities are recommended since it may be necessary to adapt the viscosity to the vehicle's usage conditions and the weather conditions. 

Viscosity is not indicative of the quality or suitability of the oil. It is just one of the properties to take into account when choosing a lubricant. However, quality level is what sets one lubricant's properties apart from another. These quality levels are usually indicated on the label.  

It is not advisable to mix lubricants with different viscosity levels. You should only do this when really necessary such as refilling when the oil level is low. You should use an oil with the same quality level as the one used in the vehicle and, if possible, from the same manufacturer.

How can I know the viscosity of a lubricant when buying it?

The SAE organization has established an internationally accepted standard based on the differentiation of viscosity at different temperatures. 

This classification defines a series of grades for engine oils and contains two subclassifications: one designated by a "W" which refers to the properties of the oil at low temperatures, and another without "W" which refers to the properties at high temperatures.

Therefore, oils designated with a numerical grade followed by the letter W (such as SAE 10W) or simply with a number (such as SAE40) are called "monograde" oils. On the contrary, those which are designated by the two types of grade (such as SAE 10W-40) are called "multigrade" because they are capable of simultaneously bringing together viscosymetrical properties at both low and high temperatures.

How often do I have to change the lubricant?

The time interval between lubricant changes is not the same for all vehicles. This time interval is determined by vehicle manufacturers according to the quality level of the lubricant, the engine characteristics, and the vehicle usage conditions. In general, it is associated with two parameters: mileage or use time in months or years, whichever comes first.

Some vehicles have built-in electronic systems that monitor the status of the lubricant in order to inform the driver when the oil must be changed.

Can I simply refill the lubricant tank or do I have to change the lubricant?

Under no circumstances can refilling the lubricant tank replace a full lubricant change since it does not completely regenerate it.

The fact is that, with use, the lubricant is degraded and loses effectiveness. Once its lifetime has been exceeded, its qualities become altered and protection of the engine elements is no longer guaranteed. Therefore, it is necessary to renew the oil on a regular basis. 

The oil has turned black. Does that mean I have to change it?

The black color of the lubricant does not mean that it is not in good condition, but rather indicates that it is working properly. Soot and other impurities are generated during the engine combustion process, and the lubricant must trap these.  

One of the lubricant's functions is to keep the engines internal components clean, due to which it darkens over time.

Which lubricants are marketed by Repsol?

Repsol markets a wide range of lubricants to meet the needs of both the professional sector and individual customers, for automobiles and motorcycles.

You can find out which lubricant is recommended for your vehicle by using our lubricant search engine

What is the ADOC program?

The ADOC program is an exclusive service offered by Repsol to business customers. This service makes it possible to offer an accurate diagnosis of the condition of the lubricant in your vehicles or machines based on the analysis of a used oil sample.

For further information about this program, click on the link that interests you:

Can a lubricant reduce fuel consumption?

Modern lubricants must be put through trials to certify that they lower fuel consumption or certain properties inherent to that feature are required. Some manufacturers' specifications highlight the fuel saving properties of the product, which are usually used to promote it.

What are low ash lubricants?

They are lubricants that are specifically designed for diesel vehicles that have particle filters as an exhaust gas treatment system. These lubricants must have an appropriate composition to make them compatible with this type of device.

What is a DPF or particle filter?

It is an exhaust gas treatment system that reduces the emission of particles into the atmosphere, particularly the soot produced by combustion in diesel vehicles. DPFs can deteriorate if the correct oils are not used. Repsol's catalog features a wide variety of lubricants that are compatible with this type of systems, looking after them and lengthening their life.

Management of used oils

At Repsol, we are committed to the environment. This is why we have assumed the chairmanship of SIGAUS (integrated management system for waste oils), an entity that collects and subsequently treats used oil of both industrial and vehicle origin.

Recycling of containers

We actively participate in the Ecoembes Integrated Management System (SIG), which collects and sorts used packaging to later recycle and treat them. At Repsol, we give the containers we use to store our lubricants a new life.

However, not only do we contribute to recycling, but we also work toward prevention. To this end, we design containers that have a lesser environmental impact, thus reducing the amount of waste they generate and facilitating recycling. This way, we don't just sell top quality products, but also strive to have the smallest impact possible on the environment.

Reverse logistics system

Furthermore, with the aim of minimizing the effects of our operations on the environment, at Repsol we have implemented a reverse logistics system that optimizes the life of some of the containers used to sell our products (containers and drums).

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