Diesel engine warranties safe

AUSTRALIAN car companies have been quick to reassure owners of diesel-powered four-wheel drive wagons that new-vehicle warranties will remain intact if additives or different grades of fuel are used to avoid mechanical failures in the snow.

A GoAuto investigation last week revealed that diesel fuel in many late-model 4WDs was freezing in sub-zero conditions, a problem particularly apparent in modern common-rail diesel engines with finer fuel-injection nozzles.

Over the past week, car-makers have scrambled to check reports of problems from dealers and owners, however none to date have reported issues concerning freezing fuel, fuel lines or ignition systems.

All companies GoAuto contacted insisted that warranties would be honoured if issues over fuel quality were found.

Three distinct diesel fuel blends are available in Australia throughout the year – summer, winter and alpine.

The latter is specifically available in regional areas close to the snow, meaning owners who fill up in metropolitan areas with winter-grade diesel could be risking mechanical failure if their vehicles were parked for long periods at regional ski resorts.

Melbourne City Land Rover spokesman Chris Pearce insisted that most owners of dieselpowered Range Rover and Discovery 4WDs were aware of the need to use winter and alpine-blend fuels.

Winter diesel has a lower "cloud point" – the point at which the wax in the fuel solidifies – and is specifically blended not to freeze.

All diesel fuel uses liquid wax for the combustion process, with alpine diesel adding more additives for the harsher snow country.

Despite last week’s big freeze across southern Australia, Mr Pearce said he had not received reports of freezing fuel from owners.

"We can only assume our owners know to put the alpine fuel mix in their cars when they go to the snow," he said.

Similar reports were received from Audi, Mercedes-Benz, Volkswagen, Mitsubishi and Toyota.

"I’ve not heard of any fuel problems like that affecting our vehicles," said Audi Australia spokesperson Anna Burgdorf.



Like all car manufacturers, Audi spends millions testing its vehicles in extreme climates before they go on sale.

"We do extensive cold-weather as well as hot weather testing of our cars," she said.

Audi Australia also constantly monitored issues related to winter driving, such as winter tyres and the issue of snow chains in each state, she said – "but the fuel issue is not one that’s come up".

Mercedes-Benz Australia spokesman Toni Andreevski said problems were not expected wit hits vehicles in local climatic conditions, and that if there were diesel-related issues these would not affect warranties.

"It’s not something we anticipate," he said.

He added that all current Mercedes CDi diesels incorporated fuel-heating systems mounted to the engine to provide trouble-free operation in temperatures down to minus-25 degrees – providing winter-grade fuel was used.

Volkswagen Group Australia echoed the other manufacturers’ views and did not anticipate warranty issues concerning the wrong diesel mix.

However, VW spokesman Matthew Wiesner said owners who had been affected at the snow "may have taken the view that it was a minor problem".

Mitsubishi Australia spokesman Kevin Taylor said any warranty issues would be approached on a "case-by-case" basis, while a Toyota spokesperson said all 4WD diesel owners’ manuals made clear reference to using diesel fuel tailored to climatic conditions.

For Toyota diesels, it clearly identifies the specific need for winter diesel in colder climates.

The alpine blend is specifically available to regional areas of NSW, the ACT and Victoria.

However, there are some mixed messages about the need for alpine fuel.

Some service stations that GoAuto contacted this week in regional Victoria did not sell the alpine mix, arguing the winter fuel was just as good at preventing fuel freezing.

Several petroleum companies also had no idea where, or even if, alpine mix was available through their networks, while the Canberra-based Australian Institute of Petroleum had no data available to the public on the recommended diesel fuel for winter conditions.

There are several diesel mixes on the market at any given time and, according to BP Australia, the wax levels used for ignition can change month to month.

The winter mix has a lower tendency for waxing "for improved but not complete protection from alpine conditions".

The BP website outlines appropriate requirements for using diesel fuel in snow areas.

There is a two-month lead-time in the distribution of the fuel so diesel bought in May would be winter grade for the cold period from the start of May until the end of July.

BP recommends changing over all fuel by May to avoid winter waxing problems and urges vehicle owners not to keep summer fuel for winter use.

In Victoria, BP alpine diesel is only sold at Wangaratta and Mansfield but other petroleum companies sell the mix in Bright and Mount Beauty.

A BP technical spokesman warned that filling up with diesel fuel in Melbourne was not appropriate for alpine conditions.

Normally the wax remains liquid in the fuel, however, when diesel gets cold enough the wax will solidify. If the temperature is low enough, crystals form to block the fuel filter and the engine can stop through fuel starvation.