Choosing the right oil for your vehicle can seem like a complicated task with so many ratings and measure and oil types. A good place to start is your vehicle’s owner’s manual. You can choose an oil viscosity based on where you live or where you will be operating the vehicle. Of course it makes sense to choose oil manufactured by a reputable brand that has to adhere to agreed international standards and regulations.
Viscosity (a fluid’s resistance to flow) is rated at 0° F. For motor oil, this is indicated by the number before ‘W’ (for ‘W’inter) and at the number after the W for a higher temperature (212F). This means the oil is designed to operate and perform at both cold starting temperatures and normal operating temperatures. The first number is the low temperature rating and the higher number is the high temperature rating.
Motor oil thins as it heats and thickens as it cools. An oil can be rated for one viscosity when cold, another when hot. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example) Thicker oil generally seals better and maintains a better film of lubrication between moving parts than thin oil.
At the lower temperatures, oil needs to be resistant to becoming too thick, so that it can still flow and easily reach all of the parts of the engine where it is required, additionally, thicker oil, requires more energy for the crankshaft to turn. Excessively thick cold oil can make it a lot harder to start the engine and can also reduce fuel efficiency. In Europe, in general, a 5W oil is generally recommended for use. But for very cold climates, some synthetic oils are available at 0W rating.
Once the engine is running, the oil gets hot and becomes thinner and moves more freely within the engine.
Fully Synthetic vs part synthetic oils – Fully Synthetic oils are required by some modern high tech engines. They last longer and have better performance than other oils in all areas, from viscosity range to purity. They flow better at lower temperatures and maintain a high level of lubrication at very high temperatures. On the downside these oils are very expensive, and not every type of engine can benefit from using them. In fact they may not contain everything that your specific vehicle requires.
Part Synthetic Oils are a mix of synthetic oil mixed with organic oil. These mixes are designed to operate at heavy loads and at high temperatures, they are less volatile than fully synthetic oil so they tend to evaporate less and more slowly than synthetic oil, this means that they need to be topped up less and can be more economical. This type of oil is commonly used in 4WD vehicles/SUVs and is much less expensive than fully synthetic oil.
Lots of 4WD vehicles have a very long operating lifetime and higher-mileage oils are formulated with seal conditioners that flow into the pores of the seals to help to ‘repair’ them by restoring their shape and flexibility. Most major oil brands have an oil specifically designed for engines that have more than 75,000 miles of wear, containing additives in the oil that help to reduce engine wear and provide other anti-aging benefits.
Synthetic Oils provide more miles per gallon, they protect your engine much better than organic oil and can also help to clean sludge and deposits from your engine while also plugging leaks and repairing seals. However organic oil can be as much as 6 to 10 times cheaper than organic oil. Ordinary ‘organic’ or mineral oil is the cheapest and also the least effective type of oil.
It is worth noting also that for most engines you can switch back and forwards between synthetic and organic oil without difficulty.