Hey guys,

My car is approaching the 200K service.

Before spending $1,000+ on this service I want to get the motor checked out.

What should I ask for at the mechanics besides a compression test to gauge how healthy the motor is?

What condition do you perceive the engine to be in? Does it run quietly/smoothly, has it still got good power, is fuel consumption ok, does it use oil or loose coolant? Chances are that if it has been looked after it will be in good condition at 200k km.

It runs smooth, quiet (no lifter tick or any noises). Power is good and fuel economy is also very good.
It's been serviced by Mitsubishi since new and the worst thing I see in the service history is:
1. For the first 110km the service intervals were 15,000km. I know this is the scheduled interval however unless Mitsubishi were using fully synthetic oil I think it is too high.
2. From 110,000km the service intervals were 10,000km, however Magnatec oil was used

The issue is that it idles poorly (seems like it misses) and it uses oil.
If the oil loss is via the stem seals it's acceptable but if it's pistons rings then clearly I am better off with a new motor

What sort of oil usage are we talking? Is it using a litre per 10K? Does it blow smoke on start up or after a long downhill run? Are there any oil leaks?

If the oil usage is minimal that is to be expected, and is quite acceptable.

I very much doubt you will need a new motor after 200 K if it has been maintained correctly.

It uses 5L per 10,000km (I have just about covered 10,000km since my last oil change and have used a whole 5L oil jug in that time).
Smokes after extended idle + blipping the throttle
No smoke on start up or (from what I can tell) during normal driving.
No oil leaks

That is certainly excessive oil use!

A wet and dry compression test would be the first thing I'd be doing. At least that will tell you if your valve stem seals or rings are shot.

If it turns out the valve stem seals are gone, that is a relatively inexpensive fix.

If it's the rings, I wouldn't even bother with a rebuild. You can pick up a low k engine off eBay/gumtree for under $500.

I'd be interested to hear the results of the comp test.

From what I understand the compression test won't necessarily show if it's the rings seeing as it could be just the oil control rings that are gone rather than the compression rings.

If I need to replace the motor I will most likely just go a 6G75. To be honest a part of me is hoping my motor is gone but judging by the way it drives I think it must be valve stem seals.

If I get a compression test done I will post up the results on the forum

A blocked PCV system will result in excessive oil use, manifesting as smoking after extended idling, and will also generally lead to rough idling as the oily gunk flows backwards into the air intake and clogs up the throttle body. Blockages can be in any of the hoses with the cross pipe (front valve cover to rear cover) being the main culprit, in the valve cover baffles and a dodgy PCV valve. Check the system is clear by pulling the PCV valve from the front valve cover, pull the PCV inlet pipe from the air snorkel near the TB and blow into it with your mouth. You should be able to blow air through the system, and it should not be possible with your thumb over the PCV valve grommet. New hoses are available through Mitsu, valves cover baffles can be cleared by soaking with degreaser (remove them first!) and PCV valves are cheap through Repco (about $15). If crap has been blowing through the TB it'll need cleaning out (a gunked TB is the most common cause of rough idle in these engines), search for Mal's TB cleaning tutorial on this site. Doing this fixed my smoking issue (I thought the rings were stuffed) and smoothed out the idle like a new one.

I'll give that a go Ensoniq, though I assume that my intake would be drenched in oil if it was all down to the PCV system?

Mind you I have cleaned my TB out and it made no difference to idle

I just tested my PCV system and it appears to be working without issues.

I booked in my car to get the poor idle check, but the compression test is an additional 1.5 hours of labor, and the mechanic said that if there was loss of compression in a single cylinder then I'd know it by the way the car drives.
Does this sound about right?