The RTA outlines critical service tasks with specific values to ensure vehicle longevity: Peugeot 206 1.4 HDi Engine Specs - Fuel Injection - Scribd

Rear wheels looking like they are "cambered" (leaning inward) or a creaking sound over bumps.

The 1.4 HDi is a high-pressure common-rail diesel. Unlike older diesels, you cannot just "crank it" to re-prime. If you introduce air into the system (by running the tank dry or opening the filter housing), the car will not start. Doing it wrong can drain the battery or damage the high-pressure pump.