Originally Posted by tjboston5676
so if i run my car for a few minutes to warm the oil and then change it takig 10 minutes, that in that 10 min period every drop of oil has come out of the engine? There is no longer any oil anywhere at all? and if u put oil in the filter before you put it on its not primed? how if this any different than starting up after the car has sat there for a period of time?
No, not at all. Most all of the oil pressure is lost, which is why an engine makes clattering noises on initial start up after an oil change and that noise is damaging metal-to-metal wear going on because of virtually zero oil pressure. The additional problem of having quite a bit of old, contaminated oil left inside the engine to combine with and contaminate the new oil being poured into the engine, is a one-two punch for the engine to get hit with. Ten minutes isn't near enough time to allow the old oil to drain out of the engine. Up to about 1/2 quart more old, contaminated oil will drain out of an engine if allowed to continue draining for an hour or so. Not allowing enough time for the old, contaminated oil to drain out of the engine before pouring new oil into it, is tantamount to taking a shower with your underwear on. This does an engine no favors.
Even with a primed oil filter, that doesn't eliminate dry starts with virtually zero oil pressure. It does help to reduce it a bit, but not eliminate it. If dry starts after an oil change didn't present a problem, some people wouldn't be bothering to prime the oil filter. A vehicle sitting for a period of time doesn't remove oil pressure from the oiling system, not unless the oil filter used is so cheap that it doesn't even have an anti-drain back valve. Excessive oil changes isn't doing an engine any favors.