Short answer:
LPG Lubrication or Valve saving is a way of lowering the wearing of valve seats in an engine. This can happen faster in a LPG converted engine because it encounters higher temperatures.
Long answer:
Valve wearNot every converted engine needs it though. It depends on the material of valves and engine operating conditions. Bigger LPG systems manufacturers test their systems on different engines and they also get the information about how a certain engine is handling via their distributors and installers. All this data is gathered in a database for their installers to use, even the need for any valve saving kits for lubrication purposes.
Installers will usually suggest a valve saver kit if they believe it would benefit your engine.
Nonetheless it is advised to ask different installers to check in their databases if your car needs it or not.
It doesn't matter if we have gasoline or diesel engine, valves are going to be worn. There are standards for how long a valve should last. For example, a typical heavy duty diesel engine of a road truck should withstand 1.600.000 km without changing the valve or valve seat insert.
One of the reasons valves could get more worn out with using LPG is because engine usually encounters higher temperatures (around 900° to 950°C) than gasoline (around 600°C).
We don't want the valves to wear for several reasons:
From around 1920 tetraethyl lead was mixed with gasoline to improve its performance and lower the fuel consumption (leaded fuel). It also helped as a buffer that prevented too much friction between valves and valve seats thus increased usage life for the components. Unfortunately lead is toxic and when it went through the exhaust system it polluted the environment. It is also associated with neurotoxic effects that could lower IQ.
When it was banned, automotive industry needed a solution to prevent valve wear so they started producing hardened valve seats.
Useless fact of the day: You've probably seen the sign »Unleaded fuel only«. Even though leaded fuel as a road vehicle fuel is banned in most countries you can still find it in handful of them. One of the main reasons why you shouldn't tank leaded fuel in your car is because it would damage your catalytic converter that converts toxic gases to less toxic ones in the exhaust system.
The technology and materials for valves and valve seats are not the same in all engines. Standards can vary, but if your engine's valves and valve seats are higher quality the wear should be less of a concern. It is best to ask installers to check for the info for the same engine what are the best practices.
There are products to prevent valve wear mostly called Valve saver kits. These kits dose a fluid into the engine intake manifold which coats the valves and valve seats in a protecting wrapper, lubricates and cleans them. The kits contain a tank for the lubricant which is connected with a tube to the engine and it slowly drips drops of lubricant into the intake manifold.
Usually you would need about 1 mL of fluid per 1 L of fuel.
Companies that develop valve saver kits in alphabetical order:
German based company
Tests and certificates:
Products:
Australian based company
Tests and certificates:
Products:
Flashlube invented their LPG additive back in 1979 and they were the first on the market.
Netherlands based company
Tests and certificates:
Products:
Also check the LPG calculator or find your local LPG installer.
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