Q

RUNNING IN A DIESEL: What's the best way to run-in a diesel engine?

A

Leave factory fill of oil for the first year or 10,000 miles. For the first 1,000 miles do not exceed 3,000rpm, but make sure you reach 3,000rpm regularly.

If running in on a motorway or autobahn, regularly vary the revs. So (in mph) cruise at 70 for 15 minutes, cruise at 80 for 15 minutes,  cruise at 75 for 15 minutes, cruise at 60 for 15 minutes, cruise at 90 for 15 minutes, etc.

For the next 1,000 miles (to 2,000 miles) do not exceed 3,500rpm, but make sure you reach 3,500rpm regularly. For the next 1,000 miles (to 3,000 miles) do not exceed 4,000rpm, but make sure you reach 4,000rpm regularly. For the next 1,000 miles (to 4,000 miles) do not exceed 4,500rpm, but make sure you reach 4,500rpm at least a couple of times a week. After that, no limit, but make sure you continue to hit 4,500rpm through the gears several times a week. The benefit of this is it helps to self clean the injectors, it blows any accumulated soot out of the exhaust system and it helps to free off the piston rings, making the engine more efficient and less likely to use engine oil. 

The latest bain of a diesel driver's life is the Diesel Particulate Filter. On passive cycle the DPF will require the car to regularly be driven significant distances at 2,000rpm plus for the DPF to get hot enough to regenerate and burn off the particulates in it.

DPFs also have an 'active' cycle where additinal fuel is injected into the combustion chambers to creater hotter than normal exhaust gases to burn off particulates in the DPF. However, this does not always work and the extra fuel can instead find its way into the engine sump, contaminating the lube oil and sometimes leading to such a rise in sump oil level that the engine can start to run uncontrollably on its sump oil and will self-destruct.

Peugeot/Citroen/Ford diesel engines don't need to get quite as hot as diesels in other makes because they use an additive to help regenerate the DPF. This used to be added to a tank under the back seat, but is now contained in a bladder that needs to be repalce around every 100,000 miles.

 

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