Hello, I hope the following assists you. Peugeot recommend Total oils in their vehicles. A 2004 Boxer HDI should have Total Quartz INEO ECS 5W30 fully synthetic oil in the engine. An example of this is available at http://www.ebay.co.uk/itm/Total-Quartz-Ineo-ECS-5W30-Engine-5L-/161313905046?pt=LH_DefaultDomain_3&hash=item258f0ed996 I hope this answers your question but if I can assist further let me know and I'll reply as soon as I'm able to. Best wishes, Sean.