Engine oil is perhaps the most important component of a combustion engine, it provides separation of moving metal parts preventing seizure slowing the wear of components. Engine oil also cools the engine components including (were fitted) the turbo charger.
Engine oil options are endless, from single grade mineral oils to today's full synthetic 'race grade' oils from an equally endless number of brands with a confusing number of classifications.
Diesel engines of yesteryear were not too fussy on what oil was used, as long as it was for diesel applications it would generally provide protection, even if the oil change periods were ignored.
The modern diesel (generally 1998 onwards) however, must use the correct oil, of the correct class and be changed at the correct intervals.
Grades of oil refer to its viscosity (thickness), the lower the grade the thinner the oil. We don't have the space to explain the grade system in depth but this would easily be found on the internet.
Personally we prefer to use (were possible) an engine oil with 'body', such as 10/40, 15/40 or 15/50 as our own in house tests have shown that an engine running such oils will outlast an engine running more modern oils such as 5/30.
Unfortunately higher viscosity grade oils are simply not useable in very modern diesels, the reason for this is down to the design of modern engines.
Modern engines use very small oil galleries which a high viscosity oil would not pass through quickly enough. The modern engine is also running hotter meaning older type oils would effectively 'cook' if used.
One sometimes wonders if vehicle manufacturers have purposely designed there engines to run exclusively on these thin 'watery' oils to ensure the engines don't last too long. Diesels that ran with older style oils would easily rack up mileages of over 300k without any major engine rebuild work needed, today we see modern diesels covering not much more over 100k before a compression issue develops or some expensive to fix 'tap' appears.
Another problem would be encountered with diesel engines that utilise a DPF (Diesel particulate Filter) in the exhaust system.
The DPF is highly sensitive to the gases / particles that pass through it, use of incorrect oil would contaminate the DPF rendering it unusable to the point of blocking it.
Diesels with a DPF system MUST use correct grade and class of oil, as a rule this is a 5/30 full synthetic high performance with low SAPS and a classification of ACEA C4, ACEA C1.
Ensure you check your vehicle handbook before ordering engine oil, the wrong oil could very easily lead to a big repair bill.
Leading from engine oils it is worth mentioning oil filters, air filter and fuel filters.
With the massive greed driven motor factors battling to provide the lowest prices the supply of cheaper but inferior filters has become common.
Poor quality filters fail to trap harmful particles which cause accelerated wear of components, this leads to expensive damage.
In the past 3 years we have had multiple case of fuel system damage caused by use of non genuine 'mickey mouse' fuel filters, these cases where often related to Ford TDCI vehicles.
We strongly advise the use of original, branded filters and also advise they are purchased from a main dealer. Yes they are a little more expensive but the piece of mind they provide truly is priceless.