AUTO Q AND A: Drips on driveway cause concern
Question: My 5-year-old car has begun to leave a few drips in the driveway after being parked overnight. It's a dark oily color. How serious a problem is this? Will it get worse or be expensive to fix? I don't know anything about cars and am hopi...
Question: My 5-year-old car has begun to leave a few drips in the driveway after being parked overnight. It's a dark oily color. How serious a problem is this? Will it get worse or be expensive to fix? I don't know anything about cars and am hoping you can talk me through this.
Answer: Good job identifying the fluid color! This rules out coolant (usually green or orange) and likely transmission fluid (red when new, can become amber or red/brown when due for renewal). The two remaining possibilities are engine oil (amber, darkens considerably with age) and power steering fluid (clear, amber, or red when new, darkens also with age).
Oil leakage and/or minor seepage can come from gaskets or seals, or a faulty power steering hose. Gaskets, which are usually made of rubber, seal component sections and access covers. Engines typically have a large gasket at the bottom, sealing the oil pan to the engine block, and either one or two gaskets at the top, sealing the valve cover(s) to the cylinder head(s). Additional gaskets may be used on the front or top of the engine to seal other parts. Seals are spring assisted rubber sleeves that are used where a shaft protrudes from a component such as the engine, transmission, or power steering parts. Your engine has several of these, one at the back and two at the front, and there are several apiece for the transmission and power steering.
Gaskets typically shrink with age. Oil seepage may sometimes be mitigated by gently snugging the attaching bolts of a cover or component section. A gasket that leaks may be the result of the rubber cracking or becoming so hardened it fails to conform to the slightly expanding/contracting metal surfaces. Seals also can become hardened or worn, allowing fluid to escape. A tiny amount of seepage from a seal is acceptable, as the sealing surface requires lubrication. Sometimes an axle or driveshaft seal can leak because the shaft passing through it wobbles, due to worn bushings or bearings (more difficult to fix).
Most of the oil seepage/leakage that occurs likely does so as the vehicle is being driven. When parked, seepage/leakage collects and runs to the lowest point, then drips to the driveway. Identifying the exact location of a leak can sometimes be challenging, requiring cleaning/re-inspection, or the use of dye. Easy/inexpensive leaks are engine valve cover gaskets and the transmission pan gasket, along with a leaking oil pressure (gauge) sending unit. The worst/expensive oil leaks are the engine rear main seal, transmission front seal, and power steering rack seals. Other seals and gaskets, as well as power steering hoses, fall in between. Seal swelling additive may also be tried, prior to seal or gasket renewal. A few drips isn't a big deal, other than the environmental impact it poses. Next time the car is in for service, ask for an inspection, and get a second opinion if the news is grim. .