Otherwise 460 made in 1993 won’t serve you long enough. Make sure you service system at Volvo with installed 1.8 engine correctly. For filling up the system you will use 6.5 liters of special Green coolant type. Only exact type of antifreeze will suit Volvo 460 cooling system. Before choosing fluid note that engine code B20F and volume of 2.0 were installed to your car in 1994.
It’s obvious that every B20F motor needs good service as stated by Volvo in instruction. Better buy 6.5 liters of good antifreeze in Green color. Providing you keep the rules 1.9 motor installed in 460 of 1996 year will be long lasting. Look at Volvo’s requirements and make your 1992 460 serve longer and with no problem.