Recently took ownership of a 2008 1.8 petrol with 140k

Been reading a lot about this engine being common for piston(s) failure.

Whats the cause? How can it be prevented?

It's the piston rings that are weak on this engine.  Not much you can do about it.  Just get rid when you start seeing blue smoke or it fails MOT on HC's.

6 minutes ago, TomsFocus said:

It's the piston rings that are weak on this engine.  Not much you can do about it.  Just get rid when you start seeing blue smoke or it fails MOT on HC's.

How common is it? Only signs are blue smoke?

13 hours ago, mike-evans said:

How common is it? Only signs are blue smoke?

Was very common a few years ago.  Don't see it often nowadays but there are fewer Mk2's left on the road now, and only a small number of those are the 1.8 petrol engine.

Blue smoke is the first sign, then they'll start running rough and damage the cat etc as well.  Once you see blue smoke, it's the beginning of the end really.  Not worth the repair costs of a full engine rebuild.

Mine's on 150,000.  Burns oil at around 1 litre to 1,000 miles.

If I put cheap oil in it burns it, if I put Shell, Petronas, other expensive oil in it doesn't?

Also notice less oil consumption if I keep her to 3,500rpm / 70mph when out and about.  As soon as I push her to 4,000rpm / 80mph then she drinks the oil.

As Tom states, the rings are chocolate on them.  I don't have blue smoke yet but I don't rag her going through the gears either.