How to Choose the Best Engine Oil for Your car (And What Happens if you Don't)

Does the choice of which type of engine oil to purchase seem a bit overwhelming? If you're having trouble deciding, you aren't alone. Many novice do-it-yourselfers have the same problem, and even experienced car caretakers can be thrown for a loop by new certifications, carefully hedged manufacturer claims, and confusing specifications. While engine oil, also known as motor oil, is one of the most tested, continuously improved, and complex components you'll put in your car, it's also the least understood.

So, back to the original question and subject of this article: what is the best motor oil for your car?

The Short Answer

If you're simply looking for a quick answer that doesn't require a lot of thinking or complex knowledge on your part, here it is: the best motor oil to choose for your car is the one that the vehicle manufacturer recommends. In your vehicle's owner's manual, the manufacturer will state the type of oil they recommend, including the certification requirements and specifications. Some will even tell you what specific brand of oil they would like you to use.  They will even tell you when to change the oil. Following these recommendations will keep your engine running at maximum performance for as long as possible.

The Long Answer

If you're the type of vehicle owner who likes to know exactly what he is putting into his car and why, you'll probably want a bit more information than the owner's manual can give you. To understand what kind of engine oil is best for your car, you'll first need to understand viscosity ratings, oil additives, and classification codes and their significance when it comes to changing the oil in your car.

• Oil Additives- Oil additives are blended into engine oil to help keep the engine free of corrosion, clean, and cool. As much as 25% of the oil can be additives.
• Viscosity Ratings- Viscosity refers to the oil's ability to flow. This is how oil is rated and identified. There are two types of viscosity: single and multi. Almost all vehicles use multi-viscosity oil. The numbers on a bottle of oil are its viscosity rating, and the lower the number is, the more easily the oil will flow because it is thinner. An oil that is 10W-40, for instance, has a viscosity rating of 10 during the winter or at low temperatures, and a viscosity rating of 40 at higher temperatures.
• Oil Classification Codes- The International Lubricant Standardization and Approval Committee, or ILSAC, has certain standards for motor oils, as well as API and other organisations.  A star burst or doughnut symbol on a container of oil means the oil has been approved for current fuel economy requirements and engine protection standards. Some oil manufacturers will also list their API  or classification code as well so you can easily see whether it is the oil for you.

Choose The Right Oil

In order to choose the right oil for your car, there are several things that must be considered.

• What type of oil are you currently using? If you've been using the same kind of oil in your current car for years, and it is running well, there (usually) isn't any reason to switch brands or viscosity ratings.

• What type of oil does your owner's manual say you should be using? While using a different oil may not affect the way your car performs, it could void your warranty if you are still under one.

• How's the temperature? What's the temperature like where you live? Do you vacation in a colder climate during the winter or a hotter one during the summer? This information affects the type of oil you use. Multi-viscosity oils cover a number of temperatures, and the lower the number is before the 'W' on your oil, the better the oil will work in cooler weather.

• How old is your car? If you've been driving a 1955 Peugeot for years, and it's been running on single-viscosity oil for the majority of its life, switching to a multi-viscosity oil is not an option. Single-viscosity oils don't contain detergent, so engines build up a lot of sludge over the years when they are used. If you switch to a multi-viscosity oil after all this time, the detergent in the multi will free all that grime and sludge within the engine and could wreck a number of Peugeot parts.

• How Worn is the Engine- How long have you had your car? If the engine has been using single-viscosity oil, multi-weight oil won't be thick enough to lubricate the car parts within the engine. This is because many car parts wear down and become smaller over time, leaving gaps between themselves and other parts. To keep things running, the oil you use has to be thick enough to fill in these gaps. A thicker single-viscosity oil is a much better option than switching to multi-viscosity oil because it will be thick enough to fill in the gaps.

What if you Choose Wrong?

There's a reason manufacturers make it so easy for you to find the right kind of engine oil by placing the information right in your owner's manual. It's because if you choose wrong, the consequences aren't pretty. You could:

• Void you warranty

• End up with a car that won't start (this generally happens if the oil has a cold viscosity that is too high)

• End up with oil that shears (generally this occurs when the hot viscosity rating is too high)

• Have to deal with a worn out engine too soon if a higher viscosity oil is used than needed, which could make it harder for your engine to start

Don't take the chance of wearing out your engine or making your car parts suffer. Follow the manufacturer's recommendations when you're ready to change your oil. The manufacturer will tell you what viscosity ratings you should be looking for and will help you find the kind of oil  you need to keep your car performing at its best.