I would be more concerned with the oil light issue to be perfectly honest.
The missfire would require further informed diagnoses, however without that I would start with the plugs or coil packs.
Alex.
If you had a major crack, then I think that you would know about it.
A wet compression test is simply a way of getting an indication if you have oil ring issues.
Just drop equal amounts of oil down each bore and carry out a compression test and compare your dry and wet readings.
It is not conclusive but will give you an indication.
If you are still having issues then just give me a shout as I am just down the road in Perth.
Wont take minutes to check out the pads and get a dial out gauge on your discs to establish exactly what your issue is.
Edit : and of course as Marcus has pointed out wheels and hubs etc require an inspection as well to get to the root cause.
Alex,
DE valve stem oil seals are in stock and good to go same/next day.
You will also require head gaskets which are also in stock as well as a few other bits and bobs.
Just drop me a PM if I can help further.
Alex.
I got quoted £750 for seals, thats labour + parts, but i've opted for full rebuild at £1000 + Parts.
A genuine Nissan head gasket set is almost £400.00.