We have a 225 ton 23XL chiller that has been showing a high zinc content in the oil samples since 2004. The oil and filters are changed every year and we pull an oil sample every year.The chiller was installed in 1995 and other than routine maintenance items works fine. I can't get a straight answer from our service provider on where the zinc is coming from. I am trying to determine if it is time to budget for a compressor rebuild or change out.

Any thoughts?