What is the normal change out period? I am not sure I have seen it anywhere in writing. I also own a 1993 Dodge Mini Caravan with 150K miles and runs fine and have never changed the plugs. MB now has 100K and suspect it is time to change the plugs as I am picking up a little "stumbling" lately which doesn't come up as a diagnostic "code alert". I used to change plugs every 10K miles on older 1960 type cars.Thanks.
Larry
Larry