I have talked to quite a few people about the 1990 350sdl. Some of them tell me the engines in these are junk. I've had mine for about 16 months. A few minor problems here and there. I replaced the idler pulley, now i have to replace the oil cooler hose. I've also changed the fuel filter twice as a precaution and do oil changes every 3000. I hav'nt flushed the radiator. Is this something i should do? It has 197,500 miles.