Originally Posted By: CATERHAM
How foolish indeed it is to claim "flow doesn't lubricate".
When using a heavier oil the main bearings and big end journals may be full of oil but less lubricant is being flung out of the big end journals up onto the cylinder walls. During a cold start the reduced oil supply will inhibit proper lubrication a some rpm level. Of course if the oil is so heavy that the oil pump relief valve is open less lubricate is flowing through the entire engine including through the piston cooling jets consequently less oil is also lubricating conrod small end.
CATERHAM, in one post, you've summed up your knowledge of thermodynamics...near zero, but you do have lots of posites and feels, albeit misguided.
Firstly, the flow through piston cooling jets is pressure/density controlled...maximum oil pressure, maximum flow. Simple as that.
It's your chase for the viscosity that provides minimum manufacturer's oil pressure that will reduce such flow.
It's the reason why heavy duty engine designers are putting on bigger oil pumps (more time in relief) to guarantee cooling flow.
Look up my linked papers on pistons and lubrication...there is plenty of oil there, and plenty of oil during warmup. And due to temperature/viscosity, that oil is providing greater film thicknesses than at the hot stage.
http://www.sae.org/events/pfs/presentations/2005spikes.pdf
Check out slide 14...the pin on disk is said to be representative of top ring dynamics, and clearly, colder thick oil is doing a better job at keeping parts separated.
As per my warmup white paper, and discussions that I had with Castrol engineers, the part as the oil thins, and before the additives are active is the major wear producing part of the equation.
Funny, if you and AEHaas got your perfect oil with zero viscosity change from freezing to 150C, you would need a whole new range of additives, functional at every temperaure or wear would be cosniderably above current.
Se Solarent's discussion of the other day...with boundary becomeing more common (which you've refuted in the past), additives are going to provide the wear protection of the future.
(You still owe us the comprehensive list of all those failed engines that you've personally witnessed at the track failing due to thick oil...mentioning them has been part of your scaremongering schtick, but you never come up with the detail).
