Prefilling Oil Filters - Necessary?

I let my engine drain for a long time, so pre-filling the filter is one of many things I do to pass the time. I've owned cars that had a horizontally-mounted filter, and I could tell it takes a second or two longer to achieve pressure with an empty filter, but couldn't do anything about it, and my engines survived. This is just one of the things that land in the category "can't hurt".
 
If you're going to crank a modern engine over, you might as well leave the ignition plugged in and just start it, you'd be doing the same startup damage whether or not the ignition is plugged in because the rotating assembly is spinning

With engines equipped with a distributor, you could prime the engine by spinning the oil pump drive gear and not spin the rest of the rotating assembly.

The rotating assembly is spinning in a sump full of fresh oil and residual oil still in the top end and not at 800rpm etc. I don't do it I just let it start normally.
 
The rotating assembly is spinning in a sump full of fresh oil ...
The crankshaft isn't submerged in oil, so a sump full of oil doesn't really matter. The crank & rods just have residual oil like the rest of the engine. But yes, as long as the oil pressure builds in less than 10 seconds after an oil & filter change, then the residual oil will be enough lubrication.
 
Funny anyone who has torn down an engine knows that there is an oil film that's on the cylinder walls,lifter galleries,etc etc for a long time. So just because you drained the oil,there is still an oil film on the internals. I don't worry about prefilled oil filters.
 
The crankshaft isn't submerged in oil, so a sump full of oil doesn't really matter. The crank & rods just have residual oil like the rest of the engine. But yes, as long as the oil pressure builds in less than 10 seconds after an oil & filter change, then the residual oil will be enough lubrication.
Yes that's right but I mean you have just put 5L + of oil over it through the filler.
 
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Yes that's right but I mean you have just put 5L + of oil over it through the filler.
Pouring oil down the oil filler on the valve cover doesn't get oil in all the places that the oil pump feeds oil to, like all the bearings, cam lobes & followers, etc.
 
Pouring oil down the oil filler on the valve cover doesn't get oil in all the places that the oil pump feeds oil to, like all the bearings, cam lobes & followers, etc.
True I know but its not going down touching nothing and would be different in every engine type. You can fill an oil cover on a v8. But aside from that the crankshaft is still throwing oil (splash) explains what I mean even with residual oil.
 
^^^ The crankshaft and rods can't throw/splash much if any oil when there's no oil flow going to the bearings. But as said earlier, the residual oil everywhere is enough to lubricate for a short time (<10 seconds) while the pump sends oil to fill the empty filter and galleries.
 
The rotating assembly is spinning in a sump full of fresh oil and residual oil still in the top end and not at 800rpm etc. I don't do it I just let it start normally.
If your crank is spinning in oil, you have entirely too much oil and a concerning lack of a windage tray. You don't want that to happen as your crank will froth your oil.
 
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