Yesterday, after years of procrastination, and having mechanics not agree to replace my glow plugs, I finally replaced the glow plugs in my 2013 I30 myself, which has now done 210000 km.
It has had an intermittent long crank, smokey start on cold mornings for as long as I can remember, some days it was ok. It felt like at least one of my tradie neighbours saw me start up in a cloud of smoke in the mornings so embarrassing. I have now replaced all four with NGK Y-527J plugs, all four original plugs were open circuit.
The results are fantastic, this car has never started this well since I have had it and there is no more smoke and splutter on start. Now it starts without hesitation, every time, better than ever.
Thanks heaps to the members that offered encouragement and good advice regarding replacing glow plugs.
Beers all round!