Skip the auto shop - Our mechanics make house calls

Q: Bad mileage & strong gas smell in dipstick/oil pan - 1996 Nissan 300ZX

asked by on

I started checking out my car because I was getting very bad mileage. When checking the oil dipstick, there was a strong smell, distinctive of gasoline. I removed the oil pan and the smell was even worse. I’ve been told many, many things by other people, but I don’t want to guess and replace things until I’m able to figure out what is wrong with it and fix it the first time. My mechanic tells me that he can’t and won’t diagnose it manually. I’ve been told different things: it’s the fuel dampener, the fuel regulator, piston rings, fuel injectors, engine valves not seated right, malfunctioning engine temperature regulator/thermostat, leak in the fuel line… In your professional opinion, what is the problem?

A: Okay, so usually the answer to problems are...

Okay, so usually the answer to problems are usually hidden in the fine details. The whole reason you started noticing a problem was the gas mileage. If this was my car, I would be thinking that I have a fuel injector stuck open or for some other reason, the engine is letting more fuel be used than is neccessary. Piston rings are not air or liquid tight. If you have an incredibly rich mixture (more fuel than you can burn) it will make the oil smell like gas, but that doesn't mean anything is wrong with the rings necessarily. A leak in the fuel line would explain the mileage but not the oil smelling like gas. The only thing that explains both symptoms is that the extra fuel is entering the combustion chamber. I am betting it is something related to the system regulating fuel into the combustion chamber. I wish I could stick my finger on just one thing, but I hope I helped narrow it down a bit. Yet, if you would like, a certified technician from YourMechanic can come to your home or office, and definitively diagnose your poor gas mileage issue.

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・Save up to 30%

Get a quote

What others are asking

Q: How long do I keep repairing a nineteen year old car?

This is the most common question a mechanic will get. At 19 years and 175,000 miles, there is really no way to predict what may go wrong next. Burning one quart of oil every 500 miles is not uncommon for...

Q: Car starts, turns off, and won't restart again for five minutes.

An engine needs three things to run: fuel, spark and compression. So, your engine is not getting the right combination of these three essentials. One thing that comes to mind on a vintage vehicle such as yours is vacuum leaks....

Q: Gasoline smell from engine oil

Hello. The most common cause of the problem you are having is when engine oil blows up in one of the engine cylinders. What may be happening is that the engine cylinder pistons aren’t sealing properly due to wear and...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...