So you get a UOA. What do all the numbers/chemicals/metals mean? Here is a short "read" on where all these stuff originates.
Aluminum (Al): Thrust washers, bearings and pistons are made of this metal. High readings can be from piston skirt scuffing, excessive ring groove wear, broken thrust washers, etc.
Boron, Magnesium, Calcium, Barium, Phosphorous, and Zinc: These metals are normally from the lubricating oil additive package. They involve detergents, dispersants, extreme-pressure additives, etc.
Chromium (CR): Normally associated with piston rings. High levels can be caused by dirt coming through the air intake or broken rings.
Copper (CU), Tin: These metals are normally from bearings or bushings and valve guides. Oil coolers also can contribute to copper readings along with some oil additives. In a new engine these results will normally be high during break-in, but will decline in a few hundred hours.
Iron (Fe): This can come from many places in the engine such as liners, camshafts, crankshaft, valve train, timing gears, etc.
Lead (Pb): Use of regular gasoline will cause very high test results. Also associated with bearing wear, but fuel source (leaded gasoline) and sampling contamination (use of galvanized containers for sampling) are critical in interpreting this metal.
Silicon (Si): High readings generally indicate dirt or fine sand contamination from a leaking air intake system. This would act as an abrasive, causing excessive wear. Silicon is also used as a anti-foam agent in some oils.
Sodium (Na): High readings of this metal normally are associated with a coolant leak, but can be from an oil additive package.
-----------------------------------------------------------------------
So what are the "rule of thumb" acceptable parameters your looking for and what is causing it to show up in your sample?
Silicon (Si) 10 to 30 ppm Dirt ingestion
Air intake system, oil filter plugging, oil filler cap and breather, valve covers, oil supply. Want to test your air filter setup? This is the number that will tell you.
Iron (Fe) 100 to 200 ppm
Wear of cylinder liner, valve and gear train, oil pump, rust in systemExcessive oil consumption, abnormal engine noise,performance problems, oil pressure, abnormal operating temperatures, stuck/broken piston rings
Chromium (CR) 10 to 30 ppm
Piston ring wear, Excessive oil blow-by and oil consumption, oil degradation
Copper (CU) 10 to 50 ppm
Bearings and bushings wear, oil cooler passivating,radiator corrosion,Coolant in engine oil, abnormal noise when operating at near stall speed.
Lead (Pb) 40 to 100 ppm
Bearing corrosion Extended oil change intervals (running your oil to long)
Aluminum (Al) 10 to 30 ppm
Piston and piston thrust bearing wear Blow-by gases, oil consumption, power loss, abnormal engine noise
Silver and Tin 2 to 5 ppm 10 to 30 ppm
Wear of bearings Excessive oil consumption, abnormal engine noise, loss in oil pressure Viscosity Change Lack of lubrication Fuel dilution, blow-by gases, oil oxidation, carburetor choke, ignition timing, injectors, injector pump, oil pressureWater/Anti-freeze Coolant leak or condensation Coolant supply, gasket sealed, hose connection, oil filler cap and breather
Attention: TDR Forum Junkies 
