[aerohead]

Originally Posted by Peter7307

OK Found it after all.
The numbers are lower than 25% and are reported as 19%
A quick copy / paste of the abstract is below:

Engine friction lubricant sensitivities: A comparison of modern diesel and gasoline engines
R. I. Taylor
Shell Research and Technology Centre, Chester, UK

Abstract
Engine friction models have been developed that take account of the variations in lubricants with temperature, shear rate, and pressure. These models have been used to study the lubricant sensitivities of modern diesel and gasoline engines. Total engine friction losses for a Perkins Phaser four-cylinder, 4.0 l, turbocharged, inter-cooled diesel engine, operating at 1300 rpm, with an SAE 15W-40 lubricant, were estimated at approximately 2 kW, with the piston assembly contributing 46%, the bearings 49%, and the valve train 5%. Total engine friction losses for a Mercedes Benz M111 2.0 l gasoline engine (used in CEC sludge and fuel economy engine tests) operating at 2500 rpm, and medium load, for an SAE 15W-40 lubricant, were estimated at 1.5 kW, with the piston assembly contributing 42%, the bearings 39%, and the valve train 19%.

Pete.

Would the 19% include:
*cam follower
*pushrods/rotators/ ends
*tappets/rockers
*springs
*valve guides
?