It is well established that engine oil deteriorates faster over short journeys – but why? Rob Marshall addresses this question and looks at how you should maintain the lubrication system to minimise the effects of past and future lockdowns.
Oil chemists have a tough job. It is hard enough to develop a lubricant that provides optimum anti-wear, fuel consumption and low emissions levels in average use. Yet, these are far from normal times.
Almost since the dawn of the mass-produced motorcar, manufacturers have advised both mileage and time-based oil drain intervals, whichever occurs first. More recently, many carmakers insist on an earlier service schedule for ‘severe’ conditions. Unless you face a moderately technically-minded customer, it can be difficult to persuade an owner that gentle pottering to the local shops and back is harder on the engine oil than a longer and faster commute.
Low use, high wear
Most engine wear occurs soon after a cold-start and during the warm-up period. While many modern cars heat their coolant comparatively quickly, thanks to electronically-controlled thermostats, on-demand water pumps, and such-like, many drivers do not know (or even care) that the oil takes far longer to warm. Cold weather and short trips are especially tough on engine oil and it is precisely those conditions that many vehicles have faced repeatedly over the last four months.
BG Products highlights that “Short trips do not allow the engine oil to reach peak operating temperatures”, while Motul UK explains: “Much like brake pads and tyres, modern oils have a preferred temperature before certain elements can perform at their best. However, the sophistication of the materials used in a modern oil means that they are engineered to also provide a high level of performance until reaching this optimum.”
Additionally, if the oil does not become sufficiently hot, water and petrol contamination cannot evaporate from it. This situation promotes oil oxidation, a consequence of which is thickening. The resultant increase in viscosity reduces oil flow, meaning that it takes longer for the lubricant to reach moving parts, especially following a cold start. Oxidation also increases the oil’s acidity. While additives combat this to an extent, the risk of corrosion heightens as those antioxidant ingredients deplete. Many technicians are familiar with oil sludge but may not realise that oxidisation tends to be the root cause. Varnishes and lacquer deposits might also result from oil oxidation, which can be even harder to shift. Chemical degradation is also a further complication.
Modern engine oils contain a balance of additives to achieve the required longevity and anti-wear characteristics but they do not last forever. Indeed, they deplete faster, as the oil becomes increasingly contaminated. If the car has not been used during wintertime, which is common among classic and cherished vehicles, even fresh oil is not immune to ageing. Castrol told us that, while engine oil is generally stable (i.e. its chemicals tend not to react with each other), moisture and other impurities can still enter the sump, even if the engine is not started. Annoyingly, an oil drain and refill is unlikely to remove all of these impurities, a proportion of which is likely to remain within the crankcase. At the very best, they will reduce the life of the fresh lubricant.
A case for flushing
Going by Castrol’s logic, changing the oil and flushing-out these harmful deposits are beneficial for not only engine life but also tailpipe emissions. Indeed, a borderline MOT exhaust gas failure might be solved by an oil drain, flush and refill. Yet, you can choose from a huge variety of engine flushes, including dedicated machines that pump heated cleansing fluid around the lubrication system. Despite their availability, most garages dose a flushing additive into the old oil, instead. Unless oil changes were neglected in the past, flushing should not cause any problems but consider that they do not have to comply with any fixed technical standard. Wynn’s advises that an engine flush should have not only cleaning and acid neutralisation properties but also lubrication functions. It highlights that obtaining all three qualities from a single product is far from easy. Castrol agrees but claims that the flushing market is:
“dominated largely by solvent-based products, which can degrade engine seals and dislodge sludge in larger, denser deposits. This can cause blockages in vital oil ways and lead to oil leaks.”
The company highlights its latest Engine Shampoo pre-oil change treatment, which reduces this risk by dissolving and flushing out up to 85% of sludge, while being solvent-free. Naturally, other producers extol the benefits of flushing; this video of BG Product’s EPR at work is especially telling of its benefits: www.bit.ly/BGFlush.
Looking beyond oil
Multiple short journeys affect more components than service items alone, which you must consider. Should these components not work at their optimum, a consequence will likely be reduced engine oil life. Multiple aborted DPF regenerations, for example, risk over-contaminating the crankcase with diesel fuel, raising the oil levels excessively and speeding the rate of lubricant degradation.
BG Products also reminds us that fuel injectors, EGR valves, air intake plenums, oxygen sensors and catalytic converters are among the many critical areas on which deposits form. This highlights the benefits of further maintenance procedures, including fuel system additives and air intake system cleaners. JLM Lubricants also adds that, especially with short trips:
“Fuel injectors and GDI injectors especially carbon-up. This causes uneven spray patterns, or even leaking/dripping injectors. When the engine does not run at its optimum operating temperature, these droplets of fuel do not evaporate but wash past the piston rings and end-up in the engine oil.”
The topic about whether you should upsell an oil supplement, or not, is a contentious one. Many (but not all) engine oil blenders argue that there is no need for you to supplement their lubricants’ additive packs. The VLS shares a similar stance and told AT that:
“Oil fortifiers can actually cause issues of their own. They generally will either thicken the oil, which might make it fall outside the design viscosity and hence impact performance, or they contain additional additive metals which could cause problems with exhaust after-treatment devices.”
Yet, quality additive companies argue that, while aftertreatment compatible oil supplement additives were beneficial during pre-COVID times, they are especially relevant now. Aside from cold weather, reduced driving speeds and shorter trips place the oil at a greater risk of contamination and oxidation. Therefore, especially if we face further lockdowns in the year ahead, it may be useful to give customers’ engine lubrication systems an extra helping hand.
BG Products highlights its MOA fortifier, which is designed specifically for petrol engines and fortifies the oil against premature breakdown and degradation. JLM states that its Bortec oil additive’s anti-oxidant ingredients help the lubricant to tolerate multiple short runs, which reduces sludge formation. Furthermore, it also helps to reduce engine wear, by decreasing the risk of metal-to-metal contact before the engine oil pressure has built sufficiently, during the cold-start and warm-up phases. The Dutch lubrication experts told us that, even if the engine is not new, Bortec slows-down wear rates, as well as helping to clean the engine’s internals. It also highlights that, as the formulation represents the very latest in friction modification technology, it contains no solid particles, making it suitable for newer cars’ tighter tolerances.
Getting it right
The extra stresses that lockdown driving conditions have placed upon engine oil highlights the importance of selecting the correct lubricant. While modern oils, made by credible manufacturers and used in the appropriate applications, provide decent low temperature protection, the VLS highlights that not permitting the lubricant to reach its optimum operating temperature of between 75 and 105 degrees centigrade is far from ideal.
Using an incompatible oil specification can create even worse problems, including accelerating wear to not only the engine but also catalytic converters and particulate filters. The VLS emphasises that, as engines become ever more sophisticated, the demands on lubricants are more stringent. Therefore, it is increasingly relevant to use a product that meets the OEM requirements in full, especially in these challenging times.