I recently bought a 1987 model 300E with 190,000 miles on it for my son. The car was checked out by my mechanic and he said the car was in good condition. After the inspection, I told my son to get the transmission screen replaced and to change the transmission fluid. He returned later and told me that a different mechanic told him that if he wasn't sure as to whether the transmission was serviced regularly in the past he should not change the transmission filter and fluid because it might cause things to come loose and damage the transmission. The car has 190,000 miles on it. Help!