I'm not very pleased with my oil right now

SlantSixSullivan

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Okay, so about a month ago I changed the oil in my slant six Diplomat. I was teaching my little brother how to check the oil, since he will be driving soon. He twists off the oil cap and the first thing I notice is moisture on the bottom of the cap (a color such as antifreeze and oil mixed) but this color is NOT on the dipstick. I know I am not losing antifreeze, so I believe what I'm seeing is condensation from the cold weather. Anyway, I give it a whiff. Smells a bit like unburned fuel. Anyway, my question is this: How am I getting gas in my oil? Also, I noticed that my fuel economy is CRAP. I drove the car an hour north to look at a truck, and an hour back home. It used 3/4 of my full tank. If my fuel pump is bad, such as the diaphragm leaking, am I correct in assuming that it can leak gas into the engine, since it is mounted to the block and driven by the cam?
 

kkritsilas

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Gas in the oll is either a extremely rich fuel mixture, or you are having a lot of blow by (rings are shot). One way or another, fuel is getting past the rings and into the oil. This is bad, as the fuel will decrease the ability of the oil to keep the bearings from wearing. your poor fuel economy is an indication that the car is running really rich.

Fuel pumps failing usually results in poor fuel pressure, and you would have noticed driveability issues (you don't indicate any(.
 

jasperjacko

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fuel pump could be leaking and still run fine, but the thin oil will ruin the motor. check to make sure the crank case venting system is working also.
 

Aspen500

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That "slime" will always smell somewhat like gasoline but not strong like raw gas. The white/yellowish goo is just condensation which mixes with oil (water and oil CAN mix) then sticks to the oil cap. I'd be willing to bet there's some on the inside of the covers also. It's normal for this time of year, especially on cars that get short trips (under 10 miles) and don't get fully warmed up frequently.
With the bad mpg's the fuel pump is suspect (like the others said). Yes, a fuel pump can leak into the crankcase yet still seem to function just fine. All depends on where the internal pump leak is.

Same thing happens on new cars also.
 

BudW

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I don’t think that is fuel related.

I’m with Aspen500 and believe it to be condensation (water).

Have you taken a cold one from the fridge and notice how water condenses on outside of the bottle/can?

When you have humidity in the air and a temperature change, water will condense, either on inside or outside.
It happens – nothing you can do to change that.

All gasoline engines will condense water inside it if humidity outside is at a certain level.
Sometimes it will run to oil pan. Most times it is tiny droplets clinging onto whatever it can inside.

As engine is warmed up and driven for roughly 8 miles or so, any and all water moisture inside of engine boils out and no one will ever know the difference.

What about the people who drive less than (roughly) 8 miles?
That water moisture combines with engine oil to create sludge!
It starts out as the light grey stuff then turns into the black sticky goo that is not fun to work with.

My recommendation, is to always drive a car (roughly) 8 miles at least once every day when the car is driven, even if it means going out of your way to do so.

Short trips are an engine killer – due to sludge and from water moisture from condensation.
BudW
 

Aspen500

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One way to reduce or even eliminate the sludge is to use synthetic oil. It won't reduce the amount of condensation but also won't turn to a sludgy goo. At work any engine I go into that's always had synthetic is basically spotless inside, not even varnish. I'm talking engines with 200,000+ miles on them. Ones that have been run on conventional (regardless of oil change interval and type of use) always have at least some sludge in the bottom of the pan and usually also on inside of valve covers, timing chain covers, etc.
To put your mind at ease, I changed oil on a 2016 GMC Acadia that had less than 10,000 miles on it and there was the white/yellowish slime on the underside of the oil cap.
 

BudW

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“hg” As in Head Gasket?

If you have a leaking head gasket that is leaking coolant into crankcase (or a cracked cylinder head) – both can do that – but you will be draining more than usual during an oil change and water/coolant will come out of oil drain hole, before engine oil does (oil floats on water).
BudW
 
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