hope to be in the right forum

[91sx]

I have a 91sx fully loaded,sunroof,bla,bla,bla.This car has been in my family since 93,my brother bought it with 16,000 miles.It now has 145,500.The top half of the engine was replaced about 20 miles back,but I have noticed one thing,especially since I changed oil5/30 for the winter. On the highway I can hear a slight ringing/tiny bells noise almost,it is more pronounce with the defrost on. I wonder if it is just the 5/30 change over? The car in fact has spent all of its life in the south,till I brought it up north,so maybe the harsher weather?? Any ideas??Also would like to know if anyone has info on how I can see what type of engine I have,and is this one of the popular models .I want to find others who may have this body so more questions /upgrades can be talked about,like stock horsepower .. Any info is much appreciated.