I have read on the forum multiple times not to use PTFE products.

Does anyone know whether the Nulon oils have PTFE or is it just their additives?

I am thinking of using this oil in my next service:
http://www.supercheapauto.com.au/online-store/products/Nulon-Hi-Tech-Fast-Flowing-Synthetic-Engine-Oil-10W-40-6-Litre.aspx?pid=164751&menuFrom=60104#Cross

No, their motor oils don't have PTFE. They still sell a few PFTE products (clearly labelled) but the company has moved away from these snake oil products of the past. They make a good range of oil blends just like Penrite.

I have been reading favorable reviews for them and think I will give them a go.
Does it matter if I go 5W40 or 10W40?
The 5W40 is slightly more expensive, but for Australian conditions (especially moving towards summer) this shouldn't be necessary I assume?

5W40 is generally for newish or younger motors, if yours has 100,000k plus you should go for the 10W40.

That's the cold viscosity though, what difference would it make new or old?

The 40 is when hot which I assume would play a role if the engine is over 100,000km.
Considering factory fill is 5W30 though I think 40 should be ok?

My TJ has 235,000km and I use Shell Ultra 5w40. It uses less than a litre between 8-10k oil changes which is well within normal oil consumption parameters.
It largely depends on what oil has been used prior, and perhaps consequently, what condition the engine is in.
5w is fine if the engine is still in good shape and doesn't burn oil. 10w is fine for 6Gs in average service, and is probably the safer bet if you're unsure of its overall condition.
Either way, Nulon has a suitable synthetic or semi-synthetic oil for whichever way you want to go.

How come your oil intervals are spaced so far apart?

I have the previous records and it shows Castrol GTX or Magnatex oil used every 7,000-9,000km (serviced at Mitsubishi).

I have just over 6,000km on the HPR 10 oil in it now and was planning on an oil change in about 1,000km

How come your oil intervals are spaced so far apart?

8-10,000km is average (perhaps more frequent than average, considering the maintenance schedule has 15,000km intervals). It doesn't have forced-induction and the majority of my driving is motorway, I don't need to change it any sooner than that.
I also drive about 35-40,000km per year, so the oil gets changed every 3 months, roughly, anyway.

The servicing schedule is 15,000km but the oil change intervals are 7,500km

The servicing schedule is 15,000km but the oil change intervals are 7,500km

For diesel and turbo models (except direct-injection diesel) and severe operating conditions (frequent short run operation; more than 50% driving in heavy city traffic; prolonged idling or stop-start driving; sustained high speed driving in >32 degree temperatures; driving in dusty, sandy or salty conditions and/or continuous operation at higher than normal loading (towing, etc.))

There are exceptions to the maintenance schedule which should allow for common sense, however, such as an ATF fluid change which in both of my maintenance books suggest changing at 105k. Given the Magna's penchant for lunching transmissions, it should be at least half that interval.

I applaud your enthusiasm for maintenance, theres not enough of us out there who think prevention is the best cure.