While we all know that low oil levels are harmful to your engine, very few people, know the exact type of oil that goes into their car. Some drop the vehicle into a service center and let the mechanic handle the rest for them.
If you like to be hands-on, you know there are oil grades. The manufacturer has a recommended oil grade for your engine. Following this religiously will stop users from using the wrong viscosity oil and damaging your engine.
What Does Oil Naming Mean?
Multigrade oils have a two number gradings system. This is because they have different characteristics under different ambient temperatures. The numbers on an oil canister denote two crucial things about the oil:
- The cold weather viscosity
- The hot weather viscosity
The number before W denotes winter viscosity, while the number after the W refers to the summer viscosity.
Viscosity refers to how hard it is for the oil to flow. A lower number means the oil flows easily and is therefore thinner.
For our reference oil grades:
- 5W20: has a 5 winter rating and a 20 summer rating
- 5W30: has a 5 winter rating and a 30 summer rating
While the two oils will have the same viscosity when it’s cold, 5W20 is less dense, making it thinner than 5W30 when the temperatures pick up.
I’m I In Trouble if I Use 5W20 Instead of 5W30?
Technically no. You can get away with it once. Most frictional damage happens when the engine is still cold. The oil viscosity will still be within range for this.
However, since the oil will be thinner once the engine heats up, chances are any hairline oil leakages in the system or tolerance gaps designed to work with 5W30 could make the lighter 5W20 oil seep out.
Other more serious things could go wrong, especially in a modern ECU controlled vehicle. For instance, since the computer doesn’t know it’s moving lighter oil, it won’t adjust oil pressure accordingly.
The wrong oil pressure could cause erratic timing control, fouled spark plugs, and terrible gas mileage.
Don’t risk it. Stick to the oil grade your user manual recommends. This is the easiest way to keep your engine working fine for thousands of miles to come.
ProTip: Some manufacturers give a range. You might be lucky and find that 5W20 is still within range of a 5W30 engine. However, if you live in a hot area, stick to the higher summer rating possible for better effects.
Is Thicker Oil Always Better?
It depends on the weather and if it is still within the recommended range. If your user manual gives you an option of two oils, for instance, 5w20 and 5w30:
- Use 5W20 in winter. The oil flows better at the prevailing conditions since your car might not heat up as it would in summer
- Use 5W30 in summer. The oil will remain thick when the temperatures pick up hence protecting your engine more.
Note that a thicker oil offers better lubrication but more resistance to moving parts. You might lose some fuel efficiency.
If you don’t experience either of the two extremes in weather, you can go for any of the oils if the manufacturer allows it.
Should I Drain the Wrong Oil?
A close mixup of very closely related oils like 5W20 and 5W30 won’t cause catastrophic engine failure. However, it would help if you considered changing the oil sooner than you would and put in the recommended oil.
However, if you mistakenly use 10W50 oil instead of 5W20, you should have it drained and replaced with the right oil ASAP. The differences in viscosity are too significant and will harm your engine.
Check this too: Should I Check My Oil When The Engine Is Hot Or Cold?
Bottom Line
Don’t experiment, especially if your car is still on warranty. Stick to the oil type and grade recommended in the user manual. This will ensure you keep your warranty valid and use your vehicle within the parameters specified by the manufacturer.