I mostly use Ridge black or clear cutting oil my dad (gone54 yrs now)said that black oil has sulfur in it makes the tool wanna cut ! on slow rpm like drilling leaf spring holes i think he was right ! also on stainless Ridge clear cutting oil is all that will work says right on the jug for black pipe or stainless steel pipe with their dies made s.s. nipples for burial work...will last a looong time ! some of those specials work fine too !
