M8 (8 mm) Marine Grade 316 Stainless Steel Open Body Turnbuckle Turnbuckles should be lubricated before their first use and regularly thereafter. Turnbuckles should regularly be rinsed with fresh water. End fittings should be checked to ensure uninhibited universal movement. Turnbuckles should also be inspected regularly for signs of damage such as bent terminals or cracking at thread roots, particularly at the end of thread.