Blood is mostly made up of water, as are our organs and muscles. To read specifically about edema, swelling caused by fluid retention where excess fluid is trapped in the body's tissues, see our article Edema: Causes, Symptoms and Treatments.
If you use the Amsoil Ea15K01 and the ASM oil (For 3rd gen Prius), then you can safely go 15,000 miles between oil changes. I drive 25,000 miles per year in my Prius. Amsoil backs up their products by a written warranty.
Re: Oil Change intervals... Its just always been a basic rule of thumb to change the oil on any car every 3 to 5000 miles. But I baby my car like nobodys buisness so i change it every 2000 miles but that's just me : Give a man a fire and he's warm for the rest of the day.