Ever had the niggling feeling that something's not quite right with your van's engine? Odd rattling sounds at idle, excess smoke, seems to be using a lot of oil, that sort of thing… Nothing that a garage can easily nail down, but the kind of problem that could land you with an expensive bill later in the year.

Seems a pity that you can't see inside the engine so that you can spot what's really going on. As it happens you can, says Mike Fenton, customer services manager at Millers Oils; and the way you do it is to have a sample of the lubricant sent off for analysis.



As well as supplying engine oils Millers Oils provides an analysis service for a modest £12 to £14 a time. “You get the results in a couple of days,” he says.

They can be highly revealing. “If you've got fuel in your oil then that suggests that the injectors may not be working properly and that the engine's bearings may be suffering from premature wear as a consequence,” he says. “The presence of silica signals that there's something wrong with the air filtration system, while traces of sodium and boron could indicate the presence of anti-freeze.

“That might mean that you've got a head gasket problem — either that or somebody has accidentally topped the oil up with coolant.” What if nickel is found? “That could spell valve train wear,” he replies.

Where sampling lubricant can be really useful is if you're buying a second-hand van. “Take it for a test drive, then request permission to draw off a small amount of oil for analysis,” he advises. If the vendor says OK, then that means he's got every confidence in the vehicle concerned. If he refuses, then draw your own conclusions.


Van engines are increasingly being filled with painfully expensive synthetic lubricants with an eye to complying with increasingly strict exhaust emission regulations.

That's particularly the case if the engine's exhaust system is fitted with a Diesel Particulate Filter (DPF). DPFs will usually tolerate nothing other than low SAPS oils — oils that only contain tiny amounts of sulphated ash, phosphorus and sulphur — and such oils are almost certain to be synthetic.

If a van manufacturer advises you to use a low SAPs lubricant and you fail to do so, you're liable to find that the DPF will get clogged up. It will cost you £80 or more to get it cleaned out.

“A blocked DPF spells increased fuel consumption and higher emission levels,” says Mike Phillips, UK technical sales manager at Q8.

Total says that using a high-ash lubricant when you shouldn't can reduce a DPF's working life — usually guaranteed at 150,000km (93,000 miles) — by around 50 per cent. “One of the biggest problems you get with DPFs, however, is their failure to regenerate, ie. work properly, if a van is on city centre delivery work because they simply don't get hot enough,” says Les Dash, Shell's UK technical manager, automotive lubricants

Group 2

While synthetic prices are steep, they could start to come down a little thanks to the increased use of what are known as Group 2 oils. They're highly sophisticated mineral oils that have undergone an additional de-waxing process to expunge almost all the sulphur they contain.

Their phosphorus content is very low too and they're less than half the price of a full synthetic — a 5-litre pack of fully synthetic lubricant can cost you £20 to £25 or more —although Group 2 critics say that their need for plenty of additives can drive the cost up.

Shell is about to introduce a partly synthetic low SAPs RT4 L 15W-40 engine oil with a significant Group 2 content alongside a low SAPS fully synthetic R6 LME 5W-30. Both form part of the Rimula range.

“The new generation of oils is backwards-compatible,” says Dash. “In other words you can put them in the engines of your older vans without doing any harm.”

Always remember, however, to check the recommendations in your van's handbook before you do so.

Low Viscosity

Many synthetic lubricants have a low viscosity — so of course do some non-synthetics — creating less internal friction in the engine and contributing towards reduced fuel usage.

“You should be able to achieve an improvement in fuel consumption of around five per cent although that can be difficult to measure accurately because there are so many other variables to take into account; the weather, the route, different drivers and so on,” Dash says. Reduced fuel use does of course help to cut diesel particulate and CO2 emissions.

Extended Intervals

Another benefit brought about in part by synthetics is extended oil change intervals. “They've increased significantly over the years and some engines feature variable intervals that depend on the work the vehicle is on,” Phillips says.

“Light commercial makers are being quite cautious at present about extending the time between drains even further though, and I don't think we'll see any significant increases in the near future,” Dash observes.

Partly that may be because manufacturers feel that vans should come into the workshop reasonably frequently to have their steering, brakes and tyres checked on safety grounds; and if you've got the vehicle up on a lift or over a pit then you might as well change the oil while you're at it. This does ignore the fact that the more oil you drain, the more you've got to dispose of and that's bad news for the environment.

Regular Checks

No matter which oil you use, or how often you change it, you should still check the level regularly by using the engine's dipstick to see if it needs topping up.

“Engines with long oil drain intervals may require slightly more top-ups than those that don't,” says Dash.

“They also tend to have bigger sumps,” adds Phillips. “It seems to be the case that some engines that meet the latest Euro 4 exhaust emission regulations require fairly regular topping up, at least until they get to around 20,000 miles. Then they tend to settle down a bit.”

“Topping up is more important now than it has ever been,” says Brian Utton, UK and Ireland technical manager at Castrol. “Quite a few engines have a healthy appetite for oil, especially when new.”

Castrol is busy promoting two fully-synthetic low SAPS lubricants in the shape of Enduron 10W-40 and Elixion 5W-30.

“You should always ensure that you adhere to the vehicle manufacturer's recommendations when it comes to selecting lubricant, especially when it comes to oil changes,” says Phillips.

“In the past you could have ignored them on occasions and usually got away with it. But that's not the case with modern vans; you pour in just any old oil at your peril.”


Light commercial vehicle engines are becoming more sophisticated to help reduce exhaust emissions and keep fuel consumption as low as possible. As a consequence the type of oil used is of far greater importance than it once was.