Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Oil smells like gas!

My engine light went on a couple days ago so today I decided to check my fluids and come to find out my oil smells like gas. Why is this happening and how much is this gonna cost to get fixed? I have to drive a good distance for work and I can’t be without a car which is got me super stressed out! I’m hoping for some good new but with car repairs it’s never good news.

The Check Light is on.

Since the fuel pressure regulator is part of the fuel pump, the only other way gas can get into the oil on a fuel injected engine is thru the fuel injectors.


Yes the check light is on

I don’t think I’ve ever smelled the oil on the dipstick even once. Just curious what made you decide to test how it smelled? It’s possible what you are noticing as a gasoline odor is normal. As the engine runs a little of the exhaust gasses tend to go into the oil, which could make a noticeable odor in the oil over time, which might smell a little like gas. Try the same test on other cars maybe. Besides that,

  • If the fuel injectors were injecting too much gas this could happen, as unburned fuel might get forced past the piston rings into the oil. But for that to happen it seems like the engine would have to be running pretty rich. Do you see black smoke out the tailpipe, or a lot of black carbon soot inside the end of the tailpipe? Ask your shop to check the diagnostic codes for an overly rich operation code. I’d ask them to check the fuel trims too.

  • Did you have some work done on the fuel system recently? Or have a problem where the car wouldn’t start and you tried again and again to get it to start up? Sometimes a result of that is the cylinders get a lot of unburned fuel in them. If so that’s a temporary problem and changing the oil will fix it.

  • PCV system problems could cause this. Ask your shop to check the pcv valve and system.

Even if the fuel pressure regulator was on the fuel rail, with a vacuum connection to the intake manifold, I don’t see how fuel could get into the oil in the crankcase via that path. What am I not seeing?

The fuel pressure regulator has a rubber diaphragm.

If the diaphragm ruptures, gas is forced into the intake thru the hose from the residual fuel pressure.

The gas leaks past the piston rings into the oil.

That’s what you’re missing.


I didn’t have to sniff the dipstick as soon as I pulled it out I could smell the gas instantly, so I took a sniff and it smelled like straight gas. There is no black smoke coming out of my tailpipe. I understand that this could happen over time but I just recently got an oil change, which makes me believe there is a major problem occurring. I haven’t had any problems starting my car at all.

Or past the rings…

In the old days, gassy smelling oil could me a ruptured fuel pump diaphragm, miss-adjusted choke, stuck needle valve, too much short trip driving, misfiring ,or too much fuel pump pressure.

I once had a young man going out with my daughter who got stuck at my house with a flooded engine in his Rambler. He had just put a new fuel pump on it. I checked the pressure from the pump and it was reading 13+ psi. His car had a spec of 3 1/2 to 5. I drove him to the parts store to exchange the pump and went to work. The next day when I got home, his car was still at my house. He had changed the pump twice and it still flooded. I asked him why he had changed the pump in the first place and he said someone had told him it was time to change it. I went and picked him up and he got his old pump out of the trash and I installed and tested it and the car ran fine. The parts store had been selling him the wrong pump.

Given that you drive a fair amount, I don’t think it is short trip driving and you didn’t mention miss firing so it is probably leaking fuel injectors. Does your car have to crank longer than it used to before starting?

My car isn’t doing anything different than usual. It starts up like normal and runs good. It did seem to idle high but it was really hard to tell with all the traffic noise.

Take the car to any chain auto parts store like NAPA, AutoZone, Oreilly, etc. and have them read the code behind the check engine light and post that here. They will do this for FREE.

I do service work on computers and people call wanting their equipment fixed. They ask how much money, how long will it take, what is wrong, and a ton of other questions. All they tell me is “It doesn’t work” and expect me to have the answer to all their questions over the phone. Remember that there are a lot of problems with cars that can cause a check engine light. We need more information.

The fuel smell in the oil may be a sign. Also, is the oil level too high? I had a mower where the carb stuck open and filled the engine with gas. The oil level was way too high and stunk of raw gasoline so I knew something was up. I pulled the spark plug and gas just ran out.

I assume this is a 1996 or newer car. The code we want will be something like P0420. It will be a P with a 4 digit number afterwards.

I don’t think the napa stores in my area scan codes for customers

In fact, I don’t even see any napa employees in the parking lots, changing light bulbs and wiper blades for the customers


The code I got from autozone is p0456 evaporative emission system leak detected.

One idea, drain a quart of oil out of the crankcase, let it sit overnight in a clear jar, then visually & odor-wise compare it to another quart of new oil. You might notice the crankcase oil is separating into layers, where the new oil doesn’t.

I doubt an evap leak would be causing gasoline to get into the crankcase. But it could cause a significant gasoline odor in the engine compartment.

Evap leaks can usually be figured out by a shop using a smoke machine to find the source, if a quick visual doesn’t show anything obviously wrong w/ the various hoses and valves.

You don’t want to let this go to long. If too much gas in oil it’ll cause a cylinder wash - basically removing the oil coating from the cylinder walls and thus destroying the engine.

I strongly suggest draining and replacing the oil before starting the engine again.

Another possibility is that the oil smells like exhaust which is normal. Even on a good engine the rings do not form a perfect seal so some blowby occurs which is one of the main reasons we change our oil. Otherwise oil would last a long long time without needing to be changed.

He seems to mention that this is pretty new oil and it smells like raw gas. I have seen this on mower engines where the carb sticks open and fills the engine with gas.

There might be multiple problems with this one. Make sure the gas cap is screwed on tight and doesn’t have a leak. This can trigger the evap system codes. Inspect the gasket and if it looks cracked, buy a new cap. Clear the code and see if it comes back. This should cause gas to be getting into the oil as you mention.

Is the level of the oil higher than the full mark on the stick? It was on the mower engines in question. The oil was literally like half gas.

I don’t have NAPA around here but I think it is policy for Autozone and Oreilley to read codes and give you a printout as to what this might mean. The codes aren’t a sure answer but can point on in the right direction. The evap codes are often the gas cap.

If a Evap code is present than the evap system could be flooding out fuel smell and maybe fuel directly into the intake and over loading the system @the smell in the oil …

So I have a 91 Chevy pu, In the last year I have replaced the heads, distributor unit, oil pan gasket, tranny pan gasket, oil coolant lines, radiator. Heater core. Just changed plug wires, had timing done. Timing just did because the idle was bad, burning to much gas. It was running great. Now it’s rough, alot of gas use. The idel flexuates, oh and changed oil filter when we did oil gasket. The fluids look good. But just checked oil and well I smell for burnt oil, and noticed the stick smells like gas. I also smell gas when I start it. I’m not burning oil. I’m hoping maybe fuil filters or injectors. Im hoping someone can give me an answer please

I’d suggest you post this as a new post so more people can see it. Please give more info about your truck, mileage, why you’ve had to replace the heads, what engine it has and if the oil level seems to be increasing without you adding any oil.