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.

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: My car is running fine but, today i hear a squealing sound when my car is turned on. What could this be?

Hi there. A squealing noise as you've described sounds like a belt noise. A loose, weakened, or stretched belt may be the culprit. However, a weak belt tensioner could also be the root cause of the noise. Either of these...

Q: Lucas oil treatment

I use it, yes. But I use it on the older, worn-out engines and it helps build up the compression because it is a thicker oil and I believe it has molybdenum sulfate, which is a very good metal cleaner...

Q: What means error fault code p1978

The trouble code you listed is a manufacturer specific code, designated by the P1xxx. I have searched my files and cant find that DTC trouble code. Can you please verify that the code is P1978? However, if you'd like to...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
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...