Originally Posted By: turtlevette
Originally Posted By: OVERKILL
On both SBC's and SBF's I've observed oil out the pushrods/rockers almost instantly even with 20w-50 in the pan........
That has not been my experience on an engine that has been sitting overnight. The pushrods and lifters tend to drain. Nothing is instant.
Note I said ALMOST instantly, not instantly. There is of course a second or two of delay.
However if you legitimately have observed a long delay (you said minutes earlier) then you have other problems like perhaps a filter canister that is somehow draining. The head of oil above the pump, assuming a full filter, means that only a few rotations of the pump are necessarily to move oil to pressure-fed places that it has managed to drain out of. Unless of course the pump has to fill the filter back up again, which, if it is a large filter like an FL-1A sized can, could take a number of seconds.
Oil pumps are positive displacement. They move the same amount of oil whether it is the consistency of molasses or canola. That's also why an oil filter (or in the case of many GM engines, the filter mounting plate) has a bypass as part of it. Because that thick oil that the oil pump is tossing at it won't go through the media at the rate it is being pushed, which causes a differential to be created and the bypass opens, letting a percentage of the oil bypass the media.
Originally Posted By: turtlevette
People starting up in these extremely low temps are causing greater than average wear on their engines. I don't care what kind or grade of oil you have in it.
I live in Canada, I start in cold temperatures pretty regularly. That's why I usually run a 0w-xx oil in my vehicles. I'd rather have an oil that is 3,000cP than one that is 4,000cP when it is -30C because it isn't the pressure-fed areas of my engine that I'm worried about. The cam/bucket interface on my car for example is obviously not pressure fed. When the oil is thick, it isn't going to be getting to that interface as quickly, because it doesn't have a pump putting it there. On many engines the cylinder walls are lubricated by a spray of oil coming out between the rod/crank interface. With cold, thick oil, that stream is more like a few thick globs, many of which don't make it to the cylinder wall. This means that the piston/cylinder interface has poorer lubrication with cold, heavy oil.
The reality of the situation however is that even with these cold starts, engines in places like Alberta aren't dying early because of the cold starts they are seeing. So while you posit that they are causing greater than average wear, the reality is that this doesn't seem to be the case in practice. Common sense things like being easy on it until warmed up a bit (keeping load low) and running a sane lubricant choice appropriate for the climate (that means not using 20w-50 when it is is -30) mean that barring some mechanical failure, the engine will (and they usually do) outlast the vehicle it is fitted to.
