When was the last time you saw your doctor for a checkup? A full checkup, including a blood test? When was the last time you took your car in for a blood test?
Though it is called oil analysis, it is more like a blood test than most people realize. And it is a diagnostic tool that should be considered, especially if you plan to buy a used car.
Oil analysis can give you a very good idea of the condition of the engine, without disassembling anything. It sure beats kicking the tires and slamming the doors.
You may even want to do an oil analysis of your current car from time to time. It will point to problems in the making so you correct them before they become expensive failures.
If your car is reaching the end of its warranty period, you may want to have an oil analysis and discuss any problems with your dealer’s service manager. It helps to go on record should you have a problem later. Get it done at least 5,000 miles before your warranty expires.
Oil analysis was invented in the 1940s as diesel-electric locomotives began to replace steam engines for trains. Today, however, trucking fleets are the largest users of the service. When you measure the amount of oil required in gallons instead of quarts, it makes economic sense.
Additionally, a truck doesn’t make money unless it is moving. Unscheduled repairs are much more costly than predictable engine service. Oil analysis helps the maintenance manager predict the optimum engine life and rebuild schedule.
Most car owners change their oil according to the book, or more often. The economics of doing so make sense at around $25 per service. But motorists also are wise to have service done before something breaks.
That’s where oil analysis comes in. It generally is done using a spectrometer to determine the elements in an oil sample. Every substance gives off different wavelengths of light when heated, and no two have the same spectrum. Based on the oil anlysis, it can be determined where the foreign elements came from.
Most oil analyses test for wear metals, contaminants and oil condition, the last being of the least importance to a car owner who follows the maintenance schedule, as opposed to a fleet manager who might use the information to extend his oil-change interval.
Wear metals
As the engine wears, certain metals are carried away and suspended in the oil.
Aluminum in the oil usually is a sign of piston wear, but some may come from aluminum cylinder heads. Iron (or steel) usually suggests wear to the cylinder walls or cylinder liners in engines with aluminum blocks. Some iron also may come from piston rings if they are badly worn. And iron can come from oil pumps, crankshafts, camshafts or valves. Chrome almost always points to piston rings because many are chrome coated.
Copper can indicate worn crankshaft or camshaft bearings or worn piston rod bearings in some engines.
Tin suggests bearing and piston wear.
Lead is also an indicator of bearing wear. When leaded gas was still available, it also indicated misfueling.
Silicon, though sometimes alloyed with some pistons or cylinder liners, generally comes from airborne dirt. The source could be a bad air filter or one that is not properly installed.
Contamination
Oil contamination comes from sources other than engine wear. Boron, potassium and sodium point to an internal coolant leak. It may be from a head gasket problem or a cracked water jacket or bad seal. By the time the coolant’s glycol shows up in the oil, the leak is probably large enough to make the oil look milky.
Water in the oil may come from a cooling system leak, but it also can be due to an excessive number of short trips that do not allow the engine to warm up sufficiently to cook off condensation in the oil. This is more prevalent in cold weather.
Oil condition
Analysis will show whether the oil is oxidized from not changing it on time, from excessively high temperatures or cylinder blowby, or poor sealing between the piston rings and cylinder walls. Analysis also will look for nitration of the oil, which comes from the byproducts of combustion that can form acids in the oil that can lead to more damage. Though there aren’t many auto repair shops or dealership service facilities that offer oil analysis, their numbers are increasing. At least one fast-lube franchise does oil analysis.
It is significantly less painful than a blood test. While the oil is draining from the pan, a sample is collected. Some companies offer kits that include a syringe with a long plastic hose that can be inserted down the dipstick tube to withdraw a sample, but one must be careful not to draw any sludge coating the bottom of the oil pan. It is also important that the oil be warm, but not necessarily hot, so the bad stuff is in suspension.
Though a few operations may have an on-site spectrometer, the sample is usually sent to a lab for examination. About a week or two later, you get a full report of what the lab found–and hopefully, a clean bill of health.
Some reports will suggest possible sources of trouble, and most indicate the amount of wear metals or contamination in parts per million. But we like to leave the final interpretation to a trained professional–a technician for the car and a doctor for ourselves. No, oil analysis is not covered by your HMO.
———-
Bob Weber is an ASE-certified Master Automobile Technician, having recertified every five years since 1978. Contact him at MMTribune@netscape.net.
