Which Engine Oils to choose, 5W-40 or 5W-30?

We send our car service every 10,000KM or less, or even more. Most of the time, the car service is about changing engine oil, oil filter, engine air filter, air con filter, wheel balancing and alignment.

The 10,000KM routing service are pretty standard, but the only variable is the engine oil.

Our vehicle engine would have a little bit of wear and tear after reaching higher mileages each time we service our vehicle.

When you first time service your car engine, is probably at 10,000KM mileages, but now your mileages are hitting 100,000KM.

The Shell Helix Ultra engine oil that you are using between 10,000KM to 100,000KM should be different in order to achieve maximum engine parts protection.

Engine Oil Rule of Thumb

A good engine oil isn’t necessary to be fully synthetic or expensive. All you need is the right grade of engine oil for your car’s engine.

There 3 types of engine oils in market:
1) full synthetic engine oil 5W-40 or 5W-30 (expensive)
2) Semi Synthetic engine oil 10W-40 or 10W-30 (moderate)
3) multi grade engine oil 15W-40 or 15W-30 (economy)

Before we proceed, let’s learn What is the meaning of engine oil Label “10W-40”?

Engine oils on shelves today are “multigrades”, means that the oil falls into 2 viscosity grades.

In a 10W-40, the 10W (W = winter) simply mean the oil must have certain viscosity or “thickness” flowing at low temperature. The lower the “W” number, the less thick the easier flow of engine oil in cold temperature (0°c)

The -40 means the oil must fall within certain “thickness” at operating
temperature (100°C). The lower the number, the less thick of the oil.

How does the oil viscosity effect my car engine?

Higher viscosity oil such as 10W-40 will flow slower at high temperature compared to 10W-30; but seal better than low viscosity oil.
A thicker oil (10W-40) provide better lubricant to critical engine parts, but thicker oil creates more drag on the engine parts and reduce engine performance.

If you are living in tropical countries (Malaysia, Singapore, Thailand, etc..),

then you can ignore the first grade number with “W” and focus only on the 2nd grade. We shall consider only the last 2 digits of the oil grade = 10W-40

• -30 (less viscosity) for vehicle that have mileages that less than 100,000KM or below 5 years
• -40 (higher viscosity) for vehicle that have mileages that above 100,000KM or above 5 years

Generally, go for thicker engine oil for older engine (above 100,000KM) which is 5W-40 Shell Helix Ultra and thiner engine oil 5W-30 (below 100,000KM).

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