I had this issue when i got mine , picked the car up changed all the oils and headed to inskip towing the next day , I thought it was running a bit warm , not hot though , when i was cleaning the the car when I got home i always hose out the core as they do suffer from corrision in the salt air , and was amaised by the amount of mud that came out , now sits at about qtr on the gauge no matter what we do or tow . always hose out the core .