Originally posted by vizvo:
pitzel, I really can't agree with your claim that oil pressure isn't important. The Society of Automotive Engineers (SAE) plainly states in their Internal Combustion Engine Handbook that oil viscosity should be chosen so that a fully warmed up engine has sufficient oil pressure at hot idle. So if your 0w-20 provides enough oil pressure at hot idle, then that's terrific.
I don't have the book, but assuming that the oil retains its properties to provide adequate boundary lubrication, flow, and not pressure, is the meaningful variable.
Oil 'pressure' gauges are fitted to cars to help inform the operator of a catastrophic loss of oil, the severe depletion in the quantity of oil, or the mechanical degradation of the functionality of oil pumps and lubrication circuits.
Here's an example to think of: imagine that you are a motor, and you can either be lubricated by sucking thick milkshakes, or by sucking Coca Cola through a straw. Both milkshakes and Coca Cola are equally effective in lubricating you. Which lubrication 'system' involves more 'pressure', and which lubrication 'system' can pump a greater quantity of 'lubricant' into your lubricated parts?
The Coca Cola, right? Because it is far less viscous than the milkshakes. The Coca Cola also can flow at a much greater rate than the milkshake, with less pressure.
If (and only if) Coca Cola can perform the duties of lubrication just as well as a thick milk shake, then the Coca Cola obviously makes for a better lubricant, even though the 'pressure' through the straw is dramatically less.
I'm not adverse to your favorite oil. But if anyone has doubts, put an oil pressure gauge on the vehicle and decide for themselves from that data. As the Great Communicator himself so eloquently stated, "Trust but verify". The fact is engines without sufficient oil pressure suffer catastrophic failure.
No, engines without sufficient oil flow
Keep in mind that the data from someone stuck in traffic in Tucson, Arizona (102° F currently) might be somewhat different than from someone cruising through Regina, Saskatchewan (55° F currently).
It hits +40C here from time to time.
The issue is: Can xW-20 provide adequate valvetrain, bottom-end and intra-cylinder metal-on-metal lubrication, at the temperatures that the oil ultimately runs at in Arizona, without oxidizing at an excessive rate
If this question can be answered in the affirmative, then as long as flow rates are acceptably high, then xW-20 is just fine.
Contemporary cars that are converted to xW-20 often only need some slight modifications to the idiot light system to accomodate this reality, so that drivers are not alarmed by the lower pressures that thinner oils enable (thus reducing pumping losses in the oil circuit). Sometimes oil pumps will be slightly modified to optimize energy efficiency for a lower viscosity oil.
[ June 17, 2006, 08:21 PM: Message edited by: pitzel ]