Everyone who owns a vehicle knows that you need to regularly check the oil level due to oil consumption. (Note: If you do not know this, you’d better go check your oil.)
A certain amount of oil loss is normal due to motor oil volatility – that is, boil-off due to the high-heat conditions inside an engine.
I once attended two days of training at a quick lube (part of a major oil company chain) wherein they showed how their conventional oil lost up to 30 percent of its weight and their synthetic oil only 12 percent in a volatility test. It drove home the message I’d already adopted that synthetics were more resistant to oil consumption than conventional oils.
Oil consumption is often due to mechanical problems
Volatility isn’t the only reason you need to replenish your oil supply now and then. The problem of abnormal oil usage is far more complicated and, in fact, most of the causes are mechanical, not lubricant-related at all.
One of the major causes is engine oil leaks, as outlined in an AMSOIL technical service bulletin titled The Reasons for Motor Oil Consumption. Here are some common sources of oil leaks that lead to excessive oil consumption:
- Oil lines
- Crankcase drain plug
- Oil-pan gasket
- Valve-cover gaskets
- Oil-pump gasket
- Fuel-pump gasket
- Timing case cover
- Camshaft bearing seal
No possible source of leakage should be neglected because even a very small leak can cause extremely high oil consumption.
For example, a leak of one drop of oil every 20 feet is approximately equal to a loss of one quart of oil every 100 miles.
Here’s a way to check for oil leaks.
One way to check for external leaks is to road-test the vehicle with a large piece of light-colored cloth tied under the engine. Oil on the cloth will indicate a leak, which should be traced to its source.
I recently burned a lot of cash trying to get an oil leak fixed. The first task is accurately locating the source of the leak. In addition to leaking gaskets or seals, the problem may be worn or damaged…
- Main bearings or main bearing seals
- Connecting rod bearings
- Camshaft bearings
- Crankshaft journals
- Ring grooves or ring lands
- Wrist pins
Cooling-system problems can also cause oil consumption
Sometimes a defective cooling system can cause engine overheating, which may result in localized hot spots in some of the cylinders that can lead to scuffing and scoring of cylinders, pistons and rings, resulting in high oil consumption.
In short, few things are as simple as they initially appear.
When all is said and done, however, all these reasons for oil consumption boil down to one if your engine is mechanically sound: oil volatility.
In this matter, synthetic motor oil provides better resistance to oil consumption due to it’s naturally superior resistance to extreme heat. If you have a mechanically sound engine, use synthetic oil to reduce oil consumption and to protect your investment.
During my three decades of writing about oil, I’ve always recommended a synthetic solution.