Nothing in that post says anything about the engine design or engineering. In fact it talked about gas mileage, easier flowing ,etc... Exactly what I have been saying, its about gas mileage.
And if 5w20 was the bees knees then why did some high performance Fords like the GT500 call for a much thicker oil if 5w20 would protect and work great?
Bro, do you even read?
Why 5W20 Oil?
Some customers are reluctant to follow Ford's recommendation to use 5W-20 oil in their engines based on the incorrect assumption that Ford and other Auto Manufacturers only recommend 5W-20 oil in order to increase fuel economy. Using 5W-20 oil can increase fuel economy by about 6/10ths of a percent compared to 5W-30 and more if you are currently using a higher viscosity oil. This equates to an additional savings of 125 million gallons per year when used in all applicable Ford vehicles. Since its introduction in the 2001 MY, 5W-20 oils have saved up to 640 million gallons of gasoline in the U.S. or an equivalent 5.6 million metric tons of carbon dioxide emissions.
5W-20 oil is a thinner oil with lighter viscosity that creates less drag on the crankshaft, pistons and valvetrain. Additionally, the oil pump can pump thinner oil more easily, improving oil circulation. Any increase in fuel economy may not be noticed by the average motorist. Machined internal engine parts are more precise than the parts of 20 years ago. This means that clearances between moving parts are smaller and more exact. Thinner oil such as 5W-20 can flow more freely through the engine while still filling the spaces. Thicker oil is harder to push through the spaces between the parts. This causes the oil pump to work harder, which in turn increases oil pressure while simultaneously decreasing oil volume. A lack of oil volume results in a decrease of lubrication and cooling, which may decrease engine part life.
The lighter viscosity of 5W-20 oil flows faster at start-up compared to higher viscosity oils, which helps reduce engine wear in critical areas by lubricating parts faster. Valvetrain components at the top of the engine require immediate lubrication at start-up.
Oil additives are not recommended as noted in the owners manual. The American Petroleum Institute (API) certifies that oils such as Motorcraft 5W-20 already contain the necessary additives for friction, detergent, etc... The addition of additives may interfere and react with the additives already present in the certified oil.
To me it seems like Ford tried REALLY hard to tell people that the fuel economy difference, while measurable across
millions of vehicles, would be imperceptible to the individual driver. 0.6% fuel economy difference is going from 30.00mpg to 30.18mpg, trivial.
To put the 640M gallon figure in perspective: in 2007 (about the time of this article) the US burned 142Billion (that's with a 'b') gallons of fuel every year. The article notes MY2001 - M2007 savings of 640M gallons, or an estimated 640M/(142B*7)=0.064% of the total gasoline consumed in the US.
The reasons why a GT500, or similar limited-run high-performance car, uses thicker oil is that the specific engine power output is considerably higher than the average car, and thus temperatures are too, so a thicker oil is needed for these rare and demanding applications. Another possibility is that thicker oil is needed to properly support the connecting rods and crank under the higher loads (and thus higher bearing stresses) that a car like a GT500 sees. This does not mean that your average grocery-getter will benefit from thicker oil.
Before you look any more like a fool look up the specs of the motors when they changed from 5w30 to 5w20 in the US. I have been building motors for several decades now and have over 20 years experience, so I know the specs. Lets see if you want to back your claims up.
Post that major bearing clearance difference in those motors, you know since newer motors are so much tighter than those old piece of junk ones and require the 5w20 over the 5w30 as its so a big difference and all.
This is about so,
so much more than main bearing clearances. It's about oil passage dimensions and surface finish, oil pump tolerances and pump shape, oil filter size and location, viscous coupling between parts moving in oil, heat transfer to the oil (which is influenced by flow rate, viscosity, density, etc), and probably a dozen other things. Did you consider that the higher oil flow rates resulting from using thinner oil may allow the use of a similar bearing fit as compared to a thicker oil? At least from a bearing capacity standpoint.
Did you ever consider the following:
-The extra pumping power needed for thicker oil will stress the oil pump more and likely shorten the oil pump life.
-Thicker, more viscous, oil will not transfer heat as rapidly as thinner oil, leading to higher component temperatures and thus more wear and faster material degradation.
-The engine oil pressure regulator/bypass won't work as intended. The filter bypass valve will open earlier, causing more unfiltered oil to be pumped through the engine.
-Engine components that rely on oil pressure to function will get thrown out of whack, components like timing chain tensioners, HLAs, etc. (not that all engines have these components)
-Low oil pressure warnings assume a given flow at a pressure. A thicker oil can keep the low oil pressure warning from tripping though there may be insufficient oil flow to lubricate the engine.
-Modern engines are designed to be as small and light as possible, which means smaller oil channels. Thinner oil will flow more volume through these channels than thicker oils. A thicker oil might lead to oil starvation.
Now, let's all be reasonable here, I'm not saying that running 10W30 instead of 5W20 will explode every engine. What I'm saying is that there are many, many aspects to consider when deciding what oil to use.
However, the most important one is: why am I going against the manufacturers suggestions? I go against MFG spec in one specific case: I run 5W40 instead of 10W30 in my turbo Miata for 3 reasons (1) the turbo's oil feed sucks out some oil flow capacity, so I like a lower cold viscosity to make sure everything gets oiled, especially at startup, and a lower viscosity oil will flow more volume, (2) I've more than doubled the power output of the engine, so having a higher hot viscosity protects the crank and maintains oil pressure better under heavy load, including pressure to the oil-cooled turbo and (3) I run the oil through an oil cooler, and having the lower cold weight, again, mitigates loss of pressure/flow through the cooling core.
On all my other cars I use the MFG spec'd weight because I know that dozens or hundreds of people have given it much more thought than I ever will.