i was changing my oil today, and when i pulled out the cap, a yellow paste, more like a melted white chocolate color, was stuck in the cap, and when i pulled the stick out, the same paste was in there!!!
what could be? blow head gasket?!
please help me!
Very possibly. A large amount of water or moisture is getting into the engine. This could be a seal breach, like the head gasket or other gaskets, like intake manifold or timing cover gaskets. This car needs to be seen by a mechanic right away. Have it towed to your mechanic. Water mixed with oil ruins the lubricating power of the oil and damage to the engine will occur if you try to drive it.
Look in the radiator or cooling reservoir. If you see traces of oil floating around, chances are a blown head gasket. If the car seems to run fine, no plumes of white smoke are coming out the tail pipe, and the coolant reservoir is clean of oil, it may be another seal that has blown and leaking coolant into the engine block, like the timing cover seal or intake manifold seal.
BK is correct that the residue on the oil filler cap and the dipstick is evidence of water contamination/dilution of the motor oil–and that is definitely a bad thing.
You did not tell us the model year of the car, or the odometer mileage, but if this car is still under warranty, you need to get it to a VW dealership immediately. If it is not under warranty, then an indy mechanic would be preferable.
Just to give you another possible scenario for the residue that you observed, there is a possible (cheaper) explanation for it. If the car is commonly driven for short distances, and if the oil is not changed every 3-4k miles, that could also explain the problem. And, if you have a gunked-up PCV valve, that would exacerbate the situation.
Have your mechanic do a compression test and a leak-down test, and (possibly) have him check the coolant for the presence of combustion gases. If you have a breached head gasket, these tests should identify it. If those tests do not indicate a head gasket leak or other seal leak, then you should have him replace the PCV valve and clean out the entire PCV system, including the hoses. And, you should also re-evaluate your driving patterns and oil change regimen.
In addition to the great advice already given…I have one more scenario. Make sure your vehicle has the thermostat in place. If the thermostat is gone the engine never has a chance to get to operating temperature.
Was the entire dipstick coated in this ‘yellow paste’, or was it just part of it with clean looking oil on the rest?
If it gets below freezing where you live and the car only gets used for short trips, you could be seeing condensation in the crankcase–the engine may not be getting hot enough to cook off the normal condensation you get.
I’d keep an eye on the new oil, perhaps checking it every day, and give the car a few good long drives. If you’re getting the car thoroughly warm and you still see this happening, or you live where it just doesn’t get that cold, you may indeed have a head gasket or other serious problem.