A common mistake I've seen made in P&S threads is to forget that while oil production will go down, so will consumption.
Oil use in agriculture accounts for just a few percents of overall use nationwide in the United Kingdom and the situation will be the same in New Zealand.
Private transportation will cease post-strike and this will release huge amounts of petrol for use.
Indeed, this occurred ITTL; the Government research project from 1986-87 gave a very useful summary of fuel usage and broke it down by area. Most long-haul freight in the country was still rail-borne (thanks to regulations), and the NZRC will likely remain the sole carrier well into the future. TTL is pretty great for anyone working in a state-owned enterprise. Shame it took a nuclear war to make Taihape prosper.
Major oil-producing regions would be a big target for any kind of neo-colonialism in order to get production restarted.
What's more New Zealand has plenty of natural gas supplies which can be transformed into liquid fuels. Our friend Roger Muldoon even built a synthetic oil plant in Motuni as part of its "Think Big" projects.
OTL production stopped in 1997 but TTL it'll keep churning the stuff out well into the 2010s, what's more the stuff might even be exported overseas!
Having said that I expect that petrol will probably remain just as expensive as it was during OTL oil crises. Production will likely be a monopoly of some kind, with prices kept high to maintain the profitability of the process.
Again, I agree - weirdly, Think Big and Robert Muldoon (though I do like to imagine there's a Roger Muldoon somewhere who spent the 1970s being mistaken for Piggy) are almost singlehandedly responsible for New Zealand doing so well; working towards autarky is uncannily good doomsday prepping on a national scale.
Australia also has quite reasonable oil and gas fields, as well as surviving refinery complexes at Clyde (western Sydney, outside the radius of a 1MT airburst over downtown Sydney), Kurnell (southern Sydney, also out of range; Sydney is truly a bloated hydra that cannot be slain with only one stroke), Port Stanvac (South Australia), Bulwer and Lytton (Brisbane area), Geelong, Altona, and Westernpoint (Melbourne area; Westernpoint closed in '84 but might be useful for parts if it's well and truly clapped-out, particularly since it has the smallest capacity of the three so isn't as useful in the long run).
Most NZ oil is light-sweet and exported to Australia for refining, with Marsden Point refining imported heavy-sour. There's at least a vestigial government in peninsular Malaysia, and God alone knows what's going on in Indonesia, but there may also be room to re-expand into Southeast Asian deposits.
All of which is a very roundabout way of saying: yes.
Overseas travel and consumer goods availability are the things that will remain quite depressed.
The airline industry will definitely not be deregulated TTL and flights to Australian while likely frequent and common will be relatively expensive. The only destination left in Asia will be Hong Kong and the most I can see are a few weekly flights nothing more. Flights to Europe and the United Kingdom may happen once a week by TTL 2017, likely serving other cities en-route. TTL airline industry in 2017 will be what it was OTL in the 1960s that is growing fast but offering still expensive products.
Consumer goods manufacturing won't be off-shored overseas TTL so prices will be higher but they might be more durable, sturdier and easier to repair than today. Smartphones and tablets won't exist. Computers will be slow and clunky and be at the 1980s levels.
Sounds plausible to me. In Australasia the Pacific will remain the go-to tourist destination, not least because going somewhere which didn't get nuked even once (well, south of the Equator, anyway) will be a pleasant trip down memory lane.
An Aussie friend of mine who has worked in HQ ADF has recently passed on this bit of information that might be relevant to P&S NZ and Australia.
I'll cross post this on the main P&S thread.
Meep. That's a pants-soiling thought for NZ and Australia.
In the interests of sticking with canon and actually leaving enough of the Antipodes to write a story which isn't just Mad Max with less leather, let's handwave that nightmarish thought by saying the war escalated too quickly (about six hours from accidental tactical exchange to full-fledged strategic Exchange) for this fun gem to kick into action.
On the plus (?) side, it does lend the idea of lobbing a couple of "why not?" devices at New Zealand. I'll note it for rewrites. Does your ADF mate have any sources?