Are you changing your oil too many times ?

with efi going longer between changes may be the thing to do...just dumped the oil in our Explorer, has 195k on it. 2500 miles it is thinned to water,10w40, and very black. If I let it go any longer it will start to burn it. When I drove the diesel a lot I was changing it at 5k, using Rotella non-synthetic. Perhaps it is excessive, but when I change the oil I also rotate the rubber and give everything a quick once over...which provides me a piece of mind.
While longer intervals may be "allowable" I simply can not afford to replace the motor in the diesel...oil is the life blood, keep it fresh. Now I only put 3k miles a year, if that on the diesel. Change it every November....along with the spin on trans filter and fuel filter...