When a customer comes in complaining of trouble shifting or an odd noise when changing gears, your first reaction may be to question the health of the transmission. But because transmissions are sealed systems, it can be difficult to determine what’s really wrong. While wrenches might not be the most practical first step in the diagnostic process, analysis of the transmission lubricant can reveal information that can help accurately troubleshoot problems.
“Transmission lube analysis gives an early warning about potential problems before they result in expense and downtime,” says Richard Gapinski, driveline and ancillaries technical service manager, global lubricants technology, BP Lubricants USA.
Start by drawing a lubricant sample from the dipstick spout on an automatic transmission or from the side plug on a manual transmission.
“Make sure the transmission had been running and that the lubricant is mixed,” says Jack Zakarian, global manager, driveline technology, Chevron Corp. “You don’t want to go right to the bottom of the reservoir because if there’s any sludge or sediment that has settled out, you’ll pick up all that junk.”
After taking the sample, submit it to a qualified lab. It shouldn’t take long to receive results, which usually can be viewed electronically. The lab will run multiple tests on the sample. First, the tests check for additive elements, such as wear protection additives and detergents. Make sure the right amounts of these elements, based on the properties of the lubricant in its original state and the transmission OE recommendations, are present to ensure adequate protection.
Another test checks for wear metals. “One of the most critical elements to check for is iron,” says Zakarian. “All transmission gears have iron in them, so if you see iron in your oil, then you know that your transmission is wearing out. By looking at analyses over time, you also can tell by the amount of iron accumulating how quickly the transmission is wearing.” Other common wear metals found are copper, lead and aluminum.
Lube analysis also looks at viscosity and total acid number (TAN). Viscosity can indicate if the wrong product has been added for the transmission because the lube will be the wrong thickness. “It also tells you if it’s moved into a state of severe oxidation because the lubricant will thicken,” says Stede Granger, OEM technical services manager, Shell Lubricants.
