Most of us know that engine oil is extremely important to your engine. Today we are seeing vehicles specifying 0W-16, 0W-20, 0W-30, and other oil types and weights. Manufacturers specify the oil weight and type that the engine should use. Many car enthusiasts, repair facilities, and DIYers tend to question if the manufacturer made the right choice with the oil designation, or if there might be a better oil for the specific application or driving environment in which the vehicle is being used. Today, we’ll cover exactly what happens and what to do if you put the wrong oil in your car.
Information has been acquired from reputable sources like Mobil and the American Petroleum Institute.
What Exactly Does Engine Oil Do?
Engine oil is used as the lubricant that is circulated throughout the engine to reduce wear, friction, and heat. It is composed of both base oil(s) and additives. The additives found in engine oil are designed to help improve cleanliness, reduce friction, reduce foam, decrease corrosion, and increase the life of the oil.
Pouring engine oil into engine (CarBuzz/Valnet)
How Engine Oils Can Differ From Each Other
Although engine oils look similar, there are different designations between them. Engine oil containers have a few labels you’ll want to pay attention to before purchasing and adding the oil to your vehicle. The first is the viscosity.
Oil Viscosity Explained
Engine oil viscosity is a series of numbers separated by a hyphen. An example of this is ‘5W-30,’ where the engine oil viscosity is 5W when cold and 30 when warm. The engine oil thickens as the temperature rises, allowing a better flow during cold starts.
The ‘W’ stands for winter. This means the engine oil is designed to change its viscosity depending on the temperature.
Some engine oils use a ‘straight’ weight. These oils are indicated by one number rather than two. For example, a straight weight bottle of oil will merely have the number ‘30’ on it. These oils do not change with temperature.
An oil with a lower number for viscosity has a higher flow rate than a higher number viscosity. When using an engine oil of the incorrect viscosity, you can alter the oil pressure inside the engine. This can result in internal engine damage.
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Certification By The American Petroleum Institute
The API starburst (found on the front) and donut (found on the back) are used to indicate the product is officially certified by the American Petroleum Institute. This certification label is not found on all automotive engine oils. However, it should be, as the certification indicates that the oil meets requirements set by vehicle manufacturers.
We do not recommend using engine oil that has not been certified by the API.
Oil Type: Synthetic Vs. Non-Synthetic Oil
Engine oil types such as ‘high mileage’ and ‘synthetic’ are important. Generally speaking, synthetic oils are more resistant to varnish build-up and heat degradation. Additionally, synthetic oils have improved lubricity properties, which lead to less drag and wear on engine internals. We recommend selecting the proper type by manufacturer specifications first, then considering factors that may help prolong your engine’s life, such as high mileage.
Oil bottle labels (Source: TheLubricantStore)
Engine Oil Types
Conventional
High Mileage
Full Synthetic
Synthetic Blend
Hybrid Vehicles
European Vehicles
Heavy-Duty / Diesel
Racing
Off-road
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How Do I Find Out What Oil My Car Needs?
With all the oil types out there, it can be intimidating to decide exactly which oil your vehicle needs. Fortunately, finding out which oil the manufacturer specifies is easy. There are four ways to do this.
Check The Oil Cap
Inspect the oil cap. Many manufacturers have the engine oil specification listed on the oil cap.
Engine oil cap showing require oil viscosity (CarBuzz/Valnet)
The Owner’s Manual
Check your owner’s manual. The vehicle owner’s manual will list the engine oil type, along with additional information such as oil capacity.
Ask The Pros
Ask a dealership or parts store. Automotive dealerships and parts stores have computer systems that store all the necessary information relating to your vehicle’s designated engine oil.
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Use Reliable Service Information
Consult a service manual. Haynes, ALLDATA, and IdentiFix are just a few of the providers of aftermarket service information. These service manuals have all the information you need to find the correct oil for your engine. Additionally, these manuals also include information on how to perform repairs such as brake pad replacement, spark plug removal and installation, and oil changes.
Oil specs from Toyota Information System (TIS Toyota)
We do NOT recommend using information from online forums or other sources that are not reliable. This information may be accurate in some instances, but can be largely inaccurate. When it comes to properly maintaining your vehicle and preventing serious damage, we recommend using accurate service information when possible.
What Happens If I Use The Incorrect Engine Oil?
Depending on how drastic the difference is in the specified engine oil vs the oil you used, the effects can vary. Below, we’ll list the potential effects commonly reported from using the incorrect engine oil.
Decreased Engine Performance
Engine oil is designed to keep internal components moving freely and to prevent them from wearing out. If the wrong oil is used, engine component operation can be hindered. This can result in difficulty starting, decreased fuel economy, cylinder misfires, variable valve timing failures, engine overheating, and an illuminated check engine light.
Abnormal Engine Sounds
Many engines use hydraulic chain tensioners and cam actuators that rely on proper oil flow to maintain timing chain tension. If the oil cannot meet the required specifications, the cam tensioner can relieve tension, causing the chain to ‘slap’ or ‘rattle’. Additionally, on cold starts, engines may make abnormal or excessive noise until sufficient oil pressure has been reached, or the oil has made its way to the valvetrain.
Burning Smell And Exhaust Smoke
One common occurrence on an engine that has used too thin of a viscosity is oil burning. The oil does not sufficiently allow the piston rings to seal, causing oil consumption and a burning odor. This usually results in blue smoke being emitted from the tailpipe.
Using The Wrong Oil Can Void Your Warranty
If your engine experiences premature engine failure and the incorrect oil was used, the vehicle manufacturer can void the warranty. Although this happens in rare scenarios, we recommend avoiding it.
In extreme scenarios, engine failures can occur. In other scenarios, you may never notice the incorrect oil was used. This all depends on how different the correct engine oil is from the incorrect engine oil and the specific vehicle. We recommend only using engine oil that is recommended by the manufacturer.
How To Fix A Car With The Wrong Engine Oil
The exact fix to remedy an engine with the incorrect oil will vary depending on the specific vehicle, the length of time the incorrect oil was in the engine, and how different the required oil is from the incorrect oil that was used.
Oil Change And Oil Flush
In the vast majority of scenarios, a simple oil change will fix the incorrect oil issue. It’s advisable that an oil flush be performed when possible. Although this will increase the cost of the repair, it will provide the security of knowing that all the incorrect oil has been removed.
Engine Rebuild Or Replacement
In extremely unfortunate scenarios, an engine overhaul or replacement may be necessary depending on the level of damage that occurs. Naturally, replacing the engine on a V8-powered Ford Mustang GT is going to cost a lot more than doing the same for a four-cylinder Honda Civic. For most vehicles, a simple oil change will remedy the issue.
Engine Replacement Costs
Engine Type
Estimated Cost
Four-cylinder engine
~$4,000
V6 engine
~$5,500
V8 engine
~$8,000
The correct engine oil and amount is paramount to the proper operation of the lubrication system and critical to an engine’s longevity. We recommend using engine oil that is specified by the vehicle manufacturer. Always check the proper oil quantity and verify the level using the dipstick.
Sources: American Petroleum Institute, Nasdaq, Mobil