Make sure you service system at Volvo with installed 1.7 engine correctly. To maintain cooling system you need 6.5 liters of Green coolant. In 1990 the company produced vehicles with 1.4 engine having code of B14.4S. For sufficient use of Volvo 340 you need to use suitable antifreeze. In other way 1987 340 won’t be used quite long and efficiently.
Better buy 6.5 liters of good antifreeze in Green color. It’s obvious that every B14.4S motor needs good service as stated by Volvo in instruction. So better use Volvo’s advice for servicing 1985 340. Produced in 1988 the 1.4 engine in 340 model will serve longer by this.