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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: How do I view the average fuel consumption?

The average fuel consumption feature is displayed on the multi-information display, and shows you the fuel economy that your car has achieved since the last reset of the feature. To view the average fuel consumption, press the display button on...

Q: Serpentine belt coming off

Hello. The oil that is spitting out from the front main seal is leaking onto the serpentine belt, and belt pulleys. This is causing the serpentine belt to slip off. The front main seal will need to be replaced with...

Q: my brake master cylinder leaks fluid but not all the time

Hi there. A crack in the master cylinder can cause the issue you're experiencing. The system itself is not "pressurized" until the cap is closed and the pedal is pressed. When you're driving, the fluid is continually in motion when...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...