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

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: Not getting fuel from fuel tank replaced fuel pump and filter I have a 85 720 nissan pick up

Hi there. I would recommend checking the fuel pump fuses to be sure the fuel pump is getting power to it. Also, check the ground wire to the fuel pump as well as this is a common issue when they...

Q: Bad spark plug

If the spark plug isn't firing, the spark plug gap could possibly be to wide from high mileage. This plug could also be physically damaged or the spark plugs porcelain could be cracked. If the spark plug wires are cut...

Q: Car possibly destroying batteries

Hey there. This may be related to a bad ground connection possibly causing a short or possibly a bad voltage regulator. This is a unit that regulates the charging of the battery by the alternator. Often times, this will result...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...