I recently read an old article that Ichazo wrote about the instinctual types. I really like the term he used for Self preservation. He called it the Conservation instinct. I think that describes it better than SP. People see SP and equate it with selfish, or money hungry, which can lead to mistypings They think "I'm not selfish, so I can't be SP." or " I don't care about money, so I'm not SP." But when you look at it through the "Conservation" lens you get a fuller picture. Conservation is about preventing waste, and keeping things from becoming depleted. Some may conserve their time, energy, resources, health, money, or nature, etc. And they aren't just concerned about themselves, but those they care about.
For me, this perspective really helps me see the value of SP, re-evaluate some prejudices I've had, and recognize some of my own SP needs.
I picture it like an internal alarm that clicks on before you're on empty. And depending on whether the person is healthy or neurotic and their core E type, their alarm will sound at different times.