I have a 94 gsr. the oil sending unit is a 10mm which will screw into a 1/8 inch t. I have the 1/8 compression sleve for the tubing mounted on one side also. always using t-tape. But the 1/8 nipple will not screw into the block. i thought i might have damaged the threads but the oil sending unit is fine and will screw in with no problem. i can't find metric nipples anywhere.please help. much apprec.