Question about gasoline in your oil

It's a 2000 Dodge Neon with the 2.0L I-4 SOHC engine. Belongs to my ex. She says it's making a knocking noise, and her brother-in-law says he smells gasoline in the engine oil. But gas mileage seems to be unaffected.

I wonder if anybody has any experience with this problem. I am thinking it could be a worn-out piston ring, but I kind of doubt it as I used Syntec in it since we bought it new, and I believe it only has about 60,000 miles on it, probably less. But I don't see how else gasoline could get into the oil. Could the cylinder head be loose? Perhaps it needs to be tightened? Maybe a chipped valve? Is there some emissions part that could be causing this?

She's out-of-state now, planning to come back on Tuesday.

If the knock seems to be coming somewhere "down in the engine" it very possibly could be a rod bearing. If the knock seems to be coming from somewhere on top of the engine it could be a valve or more likely a lifter has collapsed. If it is a head gasket there are a couple tests that aren't exact but may help diagnosing. First, start the car with the coolant cap off. If you see bubbles or water pumping out the filler then it is definitely a head gasket. A second test is a simple pressure check of the cylinders and requires a tester. I think those should be around 170 (you will need to ask a service tech). You can do a leak down test also to diagnose the problem.

All of the above is really saying you need more tests to determine what the problem is.

I'm going on very little information, unfortunately.

Thanks for you help, though!

the oil could be diluted to the point that it is not providing proper lubrication to the engine. Changing the oil and filter might eliminate it temporarily. The cause of the gas/oil mix will need to be eliminated or you'll be in the same place later though. My first guess would be worn intake valves/seals. But it could be lots of things. If the oil has been diluted long enough you could be looking at a damaged motor. I'd be especially worried about the crank bearings. Anyway, the first thing I would do is change the oil ASAP and see how it runs. I might run it for a day and do it again just to make sure I get as much gas out of it as possible.


Jay