Holden Epica Diesel Problems

Yes it is, which means that if you don’t do regular runs at highway speeds, the filter is prone to clogging up and requiring either cleaning out or even replacement. The filters for this car are advertised for anything from $200 to $800 for a second-hand DPF, but you could be buying one that is well past its best.

In a more general sense, any second-hand Epica would need to be super cheap before you’d consider it, as they were a slow seller and not a particularly good quality car even when brand new. Unloved then, they’re unwanted now. There are definitely better choices.

The 5w-30 is often used and is ok as an alternative to the factory recommended oil.

The average city consumption is around 9.2 L/100 km, less than you're experiencing, but probably within the ballpark. Diesels are at their best at constant speed, which is why the highway consumption is so low, but they're not that special in the city where you're constantly accelerating and slowing.