Oil samples are pretty inexpensive up here on the west coast of Canada. About $15.00 Cdn. per sample and will tell you virtually everything you need to know. It is best if you sample at least two consectutive time at oil change time to get consistant readings. Be very careful to keep the sample bottle clean and not allow any forgien material into the sample. It will normally take about 3 days to get the results back. Your local Catapiller dealer will sell you the bottle, you return the the full bottle and they will send you the results. If you have access to a fax machine you can get the results quicker.