There is evidence to suggest this is the case but the effect is still limited and it is very difficult to measure. The constraints are as follows:

1. Bench tests have shown that most of the build-up occurs as the vehicle comes off power and to a standstill hence M/W isn’t active at the times you need it most with regards to this particular issue.

2. Ideally you require polar solvents (rather than just methanol) to attract and remove the type of carbon chains we are dealing with. This would likely comprise an aggressive chemical mix not suitable for conventional W/M systems and certainly not suitable for regular use.

3. Once an initial catalysis of oil onto the valve has occured the surface is perfectly primed for future rapid build-up regardless of how clean you get it.

We can now publish that the primary reason for the carbon build-up is due to a pyrolytic decomposition where the oil is broken down by the catalytic (reacting) action with the materials used to manufacture or coat the valve stems. In other words, the oil is reacting to the nickel and chrome alloys used to manufacture the valves.

The deposited material remains chemically active and further lube oil or recirculating carbon matter (such as from the combustion process) then deposits with ease