Wood gas engine valve lubrication/cooling

Hi woodgasers,
some time back a friend of myne visited me with his lpg fueled car, sayd its nessesery to have a special oil injected with the air/gas mix in order to lubricate/cool/protect valves in case of gas powered engines. I know l read here somewhere woodgas has enough of moist soot in it to do the job, and at the time my gas had lots of soot in but now since l use a different filtration method l see allmost no soot in the gas contacted parts. With the new sun dryed chunks there is allso allmost no moisture in the gas.
I rarely hybrid now days, burn petrol just for a few seconds at startup, so, shuld l be worryed? What is the true purpose of those oil aditives in gas engines? Wuld it be wise to do something in that matter? I wuld hate to ruin a engine becouse of some small mistake…


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Don’t know about all the additives stuff, but the valve were changed back in the 70’s to sodium filled stems and new harder metals seats so no lead gases fuels could be used. On the ejectors not a clue, good Question for @SteveUnruh to answer.
You are saying you do not have any soot/carbon going up to your engine?
Just by hot gas filtering and slyclone filtering? I need to get busy on that kind of filtering project for the 92 Dakota.


Hi, Kristijan & Bob!

Before Steve grabs his pen, a couple of extra questions:

How much oil does the motor consume on 1000 km / 624 miles?

Consumption on gasoline alone?

Consumption on woodgas only? Meaning ONLY!

If the consumption is more on gasoline alone, that’s an indication of some tar buildup has happened on the stems.

If the consumption is less on gasoline, it indicates that the woodgas is wet and
“washes off” the oil-film from the intake stems.

Further more, part-clogging of piston rings by tar increases consumption…

Tar has opposite effect on stem leakage and piston-ring leakage…


Hi Bob and Max!

Ha, learned something new. Had no idea of sodium filled valves! Interasting.

No, l filter the cool gas and yes, it seems to eliminate allmost all soot. Took me long to come to it but it was nessesery. Plastic intake manifold is not nice to clean once full of soot… l just wanted to make sure l didnt do more harm thain good with to clean gas.


Thats a hard one to anwser since l havent driven on dino for a long time now. A guess of about 2dl/1000km, thats woodgas with occasional hybriding.

Hi, Kristijan!

Ha, mixed use cannot solve a thing by measuring consumption.

As a curiosity, as i use no gasoline, the oil volume is increasing…
by condense. >340,000 km, a bit leaky piston rings.

You mean there is condense accumulateing in your oil? Or does the oil consuption increase?

Yes my oil consumption was high too when l had problems with a tared engine. Decreased compression too. Managed to solve the problem with a everyday overnight piston wash made of a mix of diesel, acetone and etanol and burned a tank of petrol. No problems ever since.

I heared that cilinder/piston tolerances in some German cars (l think Audi too) are made so that they intentionaly drink more oil, in order of better piston lubrication/protection. No wonder they last so long.

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LPG/LNG is fairly acidic when burned, so it can cause pitting and such if your engine isn’t made for it. I actually wonder if the oil is actually for the injectors instead to keep those lubricated.

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When I was working with a GM engineer, he specialized in hybrid NG engines using the vortec 5.7 v8. He told me to use the Truck version of this engine. These engines have heads with hardened valve seats, the valve seats will become brittle after a while.


Hi, Kristijan!

The oil volume is increasing by condense in the crankcase; oil + condense volume is bigger and bigger, until next oil exchange.

Splashing and outblow would be the limit, but that far it has not gone…yet!

The motor is still powerfull and has good compression.

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Hi, Kristijan!

Smaller Fiat motors were constructed to consume 60 ccm oil / 1000 km.

That is aiming at the same goal as the German ones you mentioned…


Ha, interasting. Do you drive mostly short drives? Becouse in a couple occasions l too did get some water in the crankcase, but a 40km trip down the highway boiled all the water out.
Does this condense not hurt the engine?

I think max didn’t read the original post or misunderstood the question . what matt has said I have also heard with propane or natural gas I’m sure that’s why oil has been added to the fuel to help this issue like lead in the day . I just pulled my heads to replace with ported ones and didn’t see any difference in the valve or seat ware between heads I think a few people here have had there engine apart for other reasons with no issues . but most are getting soot through to some extent.

But lpg or ng burn hotter thain petrol right? Might this be the reason allso?

I believe you are right the fuel burns more complete not as much wasted fuel leaving with the exhaust

Hi, Paul!

Would you please citate the (missed) original question!?

fun to read and time to chime in:

read this as a shortcut to the answer on the original question


In the early day’s the lead made a deposit , damped on, the valve seat so that the valve was not hitting metal on metal with the valve seat.
Later this lead was replaced by many other chemicals and the quality from the valves and valve seats is improved, read better materials used.

A bit soot and a bit tar burning during combustion do the trick as well :grin: :wink:

Max and Kristijan;
Don’t forget that woodgas contains Hydrogen.
Hydrogen , when combusted, produces H2O and heat. If the engine is cool at startup, this water gets in the crank case.
In some extend that you’l might fear, checking on the oil, that you have a gasket blown.
( slight greyish oil emulsion )

Remember: Dynofuel also contains H2

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No exactly on topic:

The spec sheet on the IHC 450 Red Diamond states that the valves rotate. Maybe for better wear ? ?

For single cylinder engines the race track people say that it is good practice to pull the starter rope until all valves are closed, compression. Head acts as a heat sink to cool the valves equal and seals the engine from moisture. But with tar it might be best to have them open at rest, as much as possible ? ?


True. I read a while ago there was a experiment made once where the engine was srarted cold, run for a few minutes, then let to cool. Simulating the grammy driver driveing a mile to the store each day and no where else. After a few cycles the crankcase fluid was a mess of oil, water and unburnt gasoline.
Ha, when someone here buys a new old car looking as if it was stright from the factory and says “oh, l had such luck! Got it from a 85 year old pensionist who only drove in town occasionaly” l can just imagine how this never propperly heated engine looks like.

So basicly you say fear not for the valves?


I think uniform wear is the purpose. Same reason cylinder walls are honed spyraly in order for piston rings to rotate some.
In my teenage days l (like all kids here) had a passion for 50cc mopeds. 2 stroke. The piston rings do not rotate and they only last for about 5-10 000 km becouse they and usualy the cylinder wall too start to form microgrooves in them, lose compression fast.

What you say on single cyl engines makes sence, but l dubt its that important. We have a walk behind grass cutter, 500ccm, fourstroke, runs everyday from spring to fall for over 40 years, still runs like a champ without such operations.


Hi, Kristijan!

About top effect heating. During the 70-ties I had a couple of Renault 4L’s.
850cc motors take the beat driving full-gas on open roads all the time.

SAE 30 oil destroyed one of them. Later, 9:1 compression ratio + synthetic 5W 50 oil and water injection made them unexhaustable on 2km long up-slopes!

Drove them with gasoline to warm up and then “motor petrolem”, which was used for tractors with compression ratios ~ 6.5:1.

Water “injection”, actually delivered in one case with a tandem carburettor and another with water nozzles in the fuel carburettor + preheated air, adjustable during drive
90 – 130*C.

With woodgas the meager fuel and steamed water content keeps the heat developement at bay. Increased compression rate is useful, if you can avoid using gasoline. Just under 14:1 makes sense, if you have to use high octane gasoline at modest power.


Hi Max!

Ha, never heared of a car being powered with petroleum (kerosine). We used to power our gras cutters (500ccm) with it, they have 2 tanks, one for petrol one for petroleum. Extremely low compression. Like you sayd, warm with gas, swich to petroleum.

But now petroleum got more exoensive thain gasoline…

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