compresion and valves

I have problems with LPG installation in my Windstar. I discovered it by checking OBD2 readings. Readings of O2 sensors while running gasoline are correct - changes from 0 to 0.8V When I switch to LPG the O2 sensor 3 shows about 0.28V. I got the compression checked: front 9.0 9.5 and 9.25, rear 8.25 7.75 and 8.5 that gives 20% difference. I suspect the valves. It is about 25000 km (18000 miles) after the valves have been replaced. What can I do to improve the compression? Are the valves pushed hydraulic (no adjusting possible) or mechanic (sorry - don't know the correct English terms). Anybody heard about FlashLube? Maybe this could help? It's dedicated for LPG and I know it's not too popular oversea.

Sorry I dont see adjustment service for the 3.0 or 3.8, hydro self adjusters it seems. About all you can do is open and inspect for damage and worn parts..
So i see you had it open up before so what was wrong before..??? I dont care to much for engine additives. They seem to cause more harm than good. It would be best to find out whats going on. that is if you want to keep it..

the valves have been burn because of incorrectly working LPG instalation, or just because of mileage - it has 210 000 km. That's what I know from previous owner. FlashLube is not an oil additve. It drips a "lubricant". Taken from site:
"LPG is a dry burning fuel and does not contain any wear reducing additives as petrol does.... The lack of valve lubrication plus the higher combustion temperature of LPG often results in premature failure of exhaust valves due to a phenomenon known as Valve Seat Recession". This is something similiar to Valvemaster added to gasoline when you have to use Pb free gasoline in cars that need Pb in it. That is probably what happend to my car. Is it possible to check damage without taking all off? Otherwise it means changing the seal and everything that goes together with such a job. If so, changing the valves won't increase the price much.

propane gas..?? I think your are speaking of. Yes you can pull the valve cover and check the upper part spring rocker arm area for metal shavings. More so if you rub your finger over the area and look closely.But using lpg gas I would change the oil more often than normal. Every 2000 miles to keep it stable.

Hello

LPG is a cleaner burning fuel that gasoline. Oil will last longer using LPG.

As to your compression problem, to check if it's the valves or the rings are the problem put a bit of engine oil in the cylinder and do the test again. If the rings are causing the low compression the compression will go up. Oil will not cause the valves to seal better as it does the rings. The compression will not go up if the valves are leaking.

Reards

Dan