1992 Aerostar 3.0 V6 with 163,000 miles. I changed the oil Feb 2012 with a Baldwin B2 filter (fits Motorcraft FL1A, the big one) and 4.5 quarts of Meijer High Mileage 10w30 ahd a bottle of SLOB (CD2 Street Legal High Performance Oil Boost). Now after 1 year it has all of 580 miles on this oil. I did a blotter and it is very clean. I did the spoon crackle test (put drop of oil on spoon and flame under to see if there is water in the oil) for moisture and it did not crackle. Seems to me that it would be a waste of oil to change it out. Probably good for another 6 months or so anyway, until we start driving it more (if my daughter would ever get her license and have anywhere to go).