The 3.0 is a little less thirsty than an OHV 4.0l but nothing to major their but as far as reliability and lifespan the 3.0 will run circles around the 4.0 in that category. The 3.0's are famous for 3-400,000 miles with very little maintenance or trouble. My advice at 90k id go ahead and swap water pump and timing cover gasket about $100 in parts but it will save your head gaskets and make sure to stay on top of oil changes and coolant flushes then six years will be easy to get out of that motor probably more. Id also swap camshaft synchro if its never been done that and coolant are the two weak spots on these motors keep an eye on those and your golden.
New DD-2009 Ford Mustang GT/CS candy apple red.
(sold)2003 XLT Tan 3.0L V6 5-speed, Lots of mods.