OziExplorer replied:

Just don't think it is going to be any cheaper to run than petrol at current LPG prices. If you are in a capital city, there is a greater difference between ULP and gas, but once you get out of the capital cities, there is substantially less difference, and an LPG vehicle costs the same to run as petrol. Considering you get between 25% to 35% less distance out of a litre of gas compared to a litre of petrol you can work on that. On a Patrol you will be up towards the 35% less. The reason why you are not seeing the all LPG Ford sell and little to no advertising for LPG conversions. Prior to GST LPG was a viable alternative financially.

CLIVEB replied:

Peter,
I have a 1994 gq EFI wagon fitted with gas.
My vehicle has done 160,000 and runs well,these motors are very durable but I believe a head gasket replacement is not uncommon at our mileage when run on gas from new.
As with any gas vehicle they run slightly hotter than on petrol.
Its reliabiliy depends on how well the conversion is done,look also for the size of the petrol tank (you need 75 litres minimum).
The main problem with these vehicles is when out back touring,no gas and not enough petrol storage.
I am considering an engine conversion for just this reason,or the removal of the gas system and installation of a 145 litre tank in addition to the 75 litre sub tank.
For running around town and local driving where gas is available money is saved by being on gas.
In my case,driving to work only,petrol for the same distance would cost me approx $10 more each week (approx 350 km).
If you are not paying extra for the gas on the cars price, you have no recovery to make and can enjoy cheaper motoring immediately.
(equates to 22 mpg at normal difference between fuel costs,this you will never get on petrol in any patrol).
Having said all this consider a turbo diesel if you intend to travel australia wide. regards

Truckster replied:

I agree with the others.

I know people who have scrapped the Gas system, as in the nowhere there isnt LPG, and they werent really getting any advantage...

Stu still has his gas system for a GQ forsale in the club magazine!

CLIVEB replied:

Peter, my vehicle is an EFI so it starts on petrol then changes over to gas once warmed up.
If you have a carby on the engine, occasional operation on petrol prevents the seals and washers drying out, and is advisable.
As gas is very dry, it has no lubrication for the valve seats,which is another reason for running on petrol once a week.
You should get the valves adjusted ,and do this regulary ( every 20-30,000 km) this way you can monitor valve reccession if it is occuring.
Most modern engines have hardened seats and this problem is not as great as with the old cast iron heads, but still should be part of your regular servicing.
There are upper cyl and valve lubricant systems available which claim to eliminate this problem (ie flashlube).
If I were you I would have the valve clearances checked as soon as the vehicle is purchased,if OK it indicates good maintenance,and should ensure no problems in this area providing the general health of the rest of the engine is good.
LPG engines usually have longer lives than petrol due to lack of crankcase dilution. regards

David replied:

Buy a Diesel mate. You won't regret it.