I have been using Foley Caterpillar in Piscataway for my Volvo TAMD-74P's,ZF transmissions, and Kohler generator. Each analysis is $20.00 which includes cost of kit, analysis, mailing and report. They send me an electronic and paper copy. They also keep a running history for each engine, trans, and generator. I also use them for all my coolants.
I have been very happy with them. My last samples stated that my coolant was low in Nitrates and PH. They suggested an additive and resample. I would have never known this if samples were not taken. If continued over a prolonged period, this can introduce cavitation in the coolant which causes galvanic corrosion. This will slowly start to pit the internal metals and cylinder liners.