It depends on what formulation of Mercon V (I am guessing that is what you mean by "Merk 5"?), the current non semi synthetic blend of Motorcraft Mercon V is a suitable fluid for those applications that call for FNR5 fluid. The Semi-synthetic says it is not for the FNR5 applications.The mechanic I went to put Merk 5 in my transmission. He put a cheap alternative. I have to have it redone. 06 ford Fusion S takes FRN5 Motorcraft. I will have to take him to small claims court. If you mechanic prints the invoice and it's not listed in what he used,you will have to insist he added.