if yours is a TB42 with Gas conversion @LandRoverGhost

some of what Arfa has said is possible

just remember, your petrol will normally be set at about 8*BTDC - and if your Gas has been set up correctly, you should be closer to 16*BTDC

it will depend on who tuned it, and how they tuned it
for Petrol / Gas economy (so you use both fuels)
for Petrol (because they dont know how to tune a car with Gas - and they ARE out there)
for Gas Economy
for Gas Power
for Gas Performance

if it has been setup for Gas - using 98 petrol will be a waste of time & money


sounds like the previous owner has it set for Gas Power