LPG and petrol use

[robert davidson]

Hi all. As LPG is growing in popularity with Jeep users can someone please tell the correct amount of petrol that should be used and when? ie.
Should the car always be started on petrol (hot or cold engine).

Thanks.Rob D

[Kramer]

Rob,

Depends on the car, but for the Jeep I have a routine where I use petrol for around 5%, works out at about 20 minutes a week. The heads have strong valveseats and don't need any specific hardening work - they live happily on a diet of LPG. The main reason why I do it religiously is for the piston compression and oil control rings - they get lubing from petrol and gas is dry on it's own.

The system should automatically start on petrol and switch over after a second or two, unless you have a really old system which were still manual. I have had 5 cars on LPG and only the first of these was a manual system goes back some 15 years now... but the current system I have on the XJ is all automatic changeover after starting.

Hope this helps, someone correct me if I'm wrong.

[robert davidson]

Ok thanks for that Kramer . I have an auto change over ( 2000rpm) but was wondering as to why and how often to use petrol. Hot here 99% of the year so car will start on gas ok. So if you were to use 20 litres in the month that should keep things in reasonable condition eh? Like this w/e I just did 2,000ks and burn't off about 1/4 tank of petrol during the trip (no lpg avail. in certain areas) So the main reason to use is for lube of rings and seals in the fuel system.

[PK]

I run petrol for about 10kms each day if I am doing say 200kms, or every second day or something.

[dirtydannyd]

dosn't an upper cylinder lubricant kit lube the valves and things so you don't need to run petrol that often?

[AussieRCBasher]

for every 2 tanks or 180L of LPG i run 1/4 tank of petrol just to keep all the seals lubed as a continous use of LPG will dry the seals out. and i also run those little bottles of lead replacement stuff in that 1/4-1/2 tank of petrol i use.

on a cold morning put it on pretol and start it. then flic over to LPG. on warmish mornings u can usually get away with starting on lpg.