The Engine Bay Service

The car that only ever does the school run is working its oil harder than the one doing motorway miles.

Some vehicle manufacturers, having spent considerable time and effort examining the use that their products are put to, have decided that there is a case for a minimal service which is little more than an engine oil and filter change. This has come about, in many cases, through the increase in car ownership leading to one or even two of the family cars being used primarily for repeated short trips, sometimes less than one mile.

What short journeys do to oil

It is these very short journeys that accelerate the build-up of contaminants within the engine oil, and the increase in the amount of sticky black deposits found in the upper reaches of the engine. This substance is commonly referred to as black death and can usually be seen around the valve gear area of the cylinder head, visible when the oil filler cap is removed.

The build-up of these substances is created by the engine not having reached its full working temperature for any length of time. When the engine is at normal working temperature, the risk of oil condensate is virtually zero, and the contamination of the oil through excess fuelling — caused by a high incidence of cold starts — is reduced to a minimum.

In severe cases the build-up of sludge can start to coat the internal workings of the engine, reducing the size of oilways and obviously restricting oil flow, as well as affecting the workings of the valve gear and piston rings, which become stuck. This leads directly to higher oil consumption and loss of power.

With the above in mind, regular engine oil and filter changes done at relatively short intervals can go a long way to reducing contaminant build-up, thereby prolonging engine life and, in the long term, reducing running costs.

Choosing the oil

In recent years engine oil technology has come on in leaps and bounds, although the oils acceptable thirty or more years ago are still easily available and can trap the unwary, as to many people oil is quite simply oil. As a minimum requirement, choose a semi-synthetic with an API rating of SG or higher. As always, check the vehicle handbook for recommended oil specifications, and if this is not available, seek properly qualified advice.

Plugs and filters

With vehicle technology marching on comes increased service life for many components. This is never truer than in the case of spark plugs, which often do not require replacement for 20,000 miles or more; consequently they are changed at full or major service intervals. However, there is absolutely no harm in taking them out for a quick inspection, and should one plug look radically different from its neighbours, further investigation would be a good idea.

Modern cars tend to run much cleaner, so the incidence of a sooted-up or oil contaminated air filter is quite rare. Replacement intervals can be similar to that of spark plugs, and again a quick inspection is all that may be required.

Aside from the other items listed in the weekly checks, that is an engine bay service done and dusted.