How often to change engine oil in a 98 Toyota Previa?

i didn't know there was such a van,i thought the last manufactured previa was made in'97. the basic oil change for all vehicles despite how old or new they are is 3 mos or 3000 miles which ever comes first.make sure you use 5w 30 of a good quality oil like castrol,or mobile;valvoline is ok too. of course synthetic is the best,but read up on how to go from conventional to synthetic. doc good luck!