Skip the auto shop - Our mechanics make house calls

Q: some smoke and oil droplets

asked by on

when I open the hood of the car, there is a cap that when i twist to open (filler cap), there is a tiny bit of SMOKE and few OIL DROPLETS coming out. Does that mean there is something wrong with the engine or it is a normal thing to have. and why? Thank you for your time.

My car has 120000 miles.
My car has an automatic transmission.

A: Presumably, when the engine is hot, you are...

Presumably, when the engine is hot, you are opening the large oil filler cap located on the valve cover. If the car is running when you open that cap, the oil supplied under pressure to the valve train could spatter out a bit, and yes you would see, not smoke (nothing is burning) but rather oil vapors, steam, or condensed "matter" because the hot vapors are hitting colder air and condensing. This is normal.

Generally, there is a baffle in the filler hole to prevent any significant amount of oil droplets from spraying out. At any rate, you should NOT open the oil filler cap, or really any openings to the engine or general accessories when the engine is running unless you have specific technical advice. If you get spattered in the eye with a hot oil droplet, that’s a problem and if you open the radiator cap when the engine is hot you will get burned. The most important thing when it comes to engine oil is to maintain it regularly.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: does flushing your coolant system fix mixed fluid buildup?

Hi there. You may have to flush the engine a few times and then run fresh water a couple times until system is clean. Then refill it with the proper coolant and distilled water in a 50/50 mixture. If you...

Q: Oil leaking and engine went out after sitting for 5 months.

If oil dumped out of the vehicle and then it stopped running, there was likely a catastrophic failure and subsequent lack of oil pressure. From your description, it sounds like there is a good chance the engine is ruined. A...

Q: Major oil leak

As you may know, there are many different places that an engine can leak oil from which makes tracing these types of leaks time consuming and tedious. Some places will leak uncontrollably at all times and others will only leak...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.