Car Care: Changing oil and other engine essentials

It's essential to use the engine oil which has been recommended for your model of vehicle. Picture / Getty Images

Grade of oil makes a difference

Although they all do a similar job, lubricate and help cool all the moving internal parts of an engine in a variety of different temperatures and conditions, there are reasons you should choose the correct engine oil for your vehicle.

In New Zealand our temperatures aren't extreme, which means oil grade requirements for individual vehicles can stay consistent throughout each season and throughout the entire country.

We are not going to get into the many different brands of oil on the market but essentially when a vehicle is still under its new car warranty period, it is extremely wise not to move away from the specific recommendations of the respective new vehicle distributors and/or their franchise networks.

Once a vehicle is well out of warranty, then oil grade recommendations (and brand) may change based on the vehicle's odometer reading or the environment it is been used in, or exposed to. But caution is still recommended.

Using a grade of oil that is not recommended by the original vehicle manufacturer can create issues such as: high fuel and oil consumption, and premature wear; while not changing the oil at the recommended time intervals will lead to a heavy build-up of sludge and ultimate engine failure.

Oil grade is basically based around its viscosity or resistance to flow. The lower the viscosity the better or faster it will flow and vice versa for a higher viscosity oil.

Multi-grade oils are able to change their viscosity according to temperature to enable fast lubrication of moving parts when an engine is cold, and a slower viscosity level when the engine is hot to provide added protection when clearances are greater.

Not all engines are the same and specific oil grades are therefore designed to be used in specific engines. The more modern engines use a very low viscosity oil which ensures all moving parts are receiving lubrication quickly, plus it has the added benefit of helping achieve an improvement in fuel consumption.

Change intervals have also been stretched out further without the risk of premature wear which helps both the environment and helps keep owners' overall running costs down.
Trying to use a low viscosity multi-grade oil in an older engine however, can create issues such as excessive oil consumption as the engine is not designed to cope with the lighter oil.

The opposite can also apply if a high viscosity oil was used in a more modern engine with an increase in fuel consumption on the cards as the engine battles with the thicker oil.
In an emergency, and if an engine required a top-up, then any grade of oil is better than nothing to avoid engine damage, but it's best to drain and refill when convenient.
As well as the oil itself, using a good-quality oil filter is also strongly recommended.
If you buy genuine, then you can't go wrong but there are other options which some reputable repairers will use and be up to the task.

If you're in doubt, and carry out your own servicing, then go genuine.

Diesel engines have also evolved over time with cleaner common rail, high-pressure direct injection engines now the norm on new diesel-powered vehicles.

The wrong diesel engine oil can contribute to particulate filter (which traps diesel soot in the exhaust system) - a situation which should be avoided at all costs.

For both petrol and diesel engines that run a timing chain instead of a rubber cam belt, oil quality is also critical. Contaminated and dirty oil will shorten the life of the chain.