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.
A local oil change recently wanted to charge $80+ for an oil change using synthetic motor oil(Valvoline)I did not do this as I was prepared to pay $19.95 qat this location as I did on my 2006 Prius.I had them use 5w20 as previous.They also stated that the oil needed to be changed at 4000 miles,whether regular or synthetic oil was used.