It started an oily substance leak but oil level reads full. It soaked a piece of cardboard and gravel underneath in one night.

ANSWER : Even though the level reads full, it could still be an oil leak. It only takes a very small amount of oil to make a huge mess. Even just a few ounces would make a huge mess, but would be hard to distinguish the loss of it on a dipstick. It could also be transmission fluid, power steering fluid, or even potentially brake fluid. I would check all of your fluid levels, and make sure that they are full.

Next time leave a white napkin on top of the cardboard, to help determine what color the leaking fluid is. Red to dark red fluid is usually automatic transmission fluid, golden brown to dark brown is usually engine oil or potentially power steering fluid, and light amber fluid is usually brake fluid, though could also be power steering fluid.

Since it seems as though the leak could be severe, it should be diagnosed by a qualified technician, such as one from YourMechanic. They can then also evaluate the severity of the leak and provide a repair suggestion and if you can wait or not.

ANSWER : Hi There,
It sounds like you may need to replace the oil cap o-ring. If you haven’t done this before there are two O-rings to replace; a small green one on the base of the filter cap stem and the large black one that seals the filter cap (which seems to be the one you are having issues with). The large O-ring sits in a small square-shaped groove that is at the base of the oil filter cap. It is very easy to not properly seat the large O-ring because the threads for the oil cap are quite large and will accept the O-ring if you are not careful. I would suggest having a professional from YourMechanic come to your location to take a look at your vehicle.

ANSWER : Oil additives are not recommended by any vehicle manufacturer for any reason. Additives that purport to resolve oil leaks are useless, a waste of your money, and may result in engine damage. Every vehicle manufacturer strongly recommends against use of these materials. There is only one recommended and approved repair strategy when it comes to oil leaks: fix the leak.

You can only add the manufacturer specified amount of oil to an engine. If you add too much oil, or too little oil, that will cause engine damage. You should check the engine oil dipstick to determine if there is presently too much oil in the engine. If there is too much, the excess will have to be removed to prevent engine damage.

The leak that you are referring to can be repaired if you request an oil leak diagnostic. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.

ANSWER : This light will usually come on when one of two things are happening. Either the motor is in fact low on oil or the oil pressure sending unit is not working properly and may be producing a faulty reading. I would recommend first, to check the actual oil level in the motor by using the dipstick. Be sure the oil level reaches the "full" mark. If this registers as "full" then you likely have a faulty oil pressure sending unit. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to determine what may be causing your low oil pressure light to come on.

ANSWER : You should find out the reason the oil is overfull. If the oil is contaminated with water then you may have a head gasket blown. If the oil is contaminated with fuel then you may have a fuel injection system flooding the engine. Either way have the oil and filter replaced (since it may be contaminated) and the correct amount of oil put in. When you have this service done, have them check why the oil was overfilled in the first place.

ANSWER : Most older cars have oil leaks. Sealing technology has just not kept up with mechanical improvements to engines so much so that leaks often kill engines rather than mechanical problems. So, it is not unexpected at all to have an, indeed many, oil leaks on a 23 year old car. Oil leaks vary hugely in terms of severity and priority of repair. Oil leaking onto a hot engine manifold is the worst case (the oil can start a fire; at best, you are left breathing oil fumes in the cabin, as the oil burns off of the manifold) while de minimus seepage of oil at the oil drain plug or oil pan gasket, while annoying and messy, if limited enough is not an emergency. Some leaks are easy to repair, while others literally require the engine to be removed just to get physical access to all the leak points. In your circumstance, if you smell burning oil, oil is probably leaking onto a hot engine part such as the exhaust manifold. A certified Mechanic, dispatched by YourMechanic right to your location, can perform an oil leak diagnostic and then let you know of your repair options and costs.

As far as the check engine light, that is not related to the oil leak(s). If you request a check engine light diagnostic, a certified mechanic from YourMechanic would use a code scanner to retrieve the specific diagnostic trouble code(s) from your car’s PCM that have caused the check engine light to illuminate. Using those codes, the appropriate individual vehicle components or sub-systems (often a sensor, circuit, and the like) are then carefully tested, based on specifications set forth in your car’s Factory Service Manual, to pinpoint the cause of the fault or the reason why the check engine light has illuminated. Once the faulty part or component is identified, it is explained to your satisfaction and the mechanic will let you know of the cost to repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : Bob: Thanks for your inquiry. Oil level and oil pressure are measured using separate sensing systems. If the level sensing feature stopped working at the time the pan gasket was replaced, either the level sensor was damaged, not reconnected, or the wire harness and terminal were damaged. There is a possibility that the wire harness was just never re-connected to the level sensor so check that first. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a warning light diagnostic – oil level and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : If the oil filter housing is integral to the oil cooler, or the housing had to be removed to service the cooler, a professional mechanic with knowledge of the limited service life of rubber seals would have absolutely (guaranteed) replaced the filter housing gasket that you are now belatedly finding leaks. However, if the leaking gasket is in an assembly that was not touched, or is not part of the cooler, they might be on reasonable grounds to have not fooled with it. These cooler configurations vary (from Mercedes Benz model to model) so, having the advice I just gave, you can just simply ask them what configuration you have and go from there. The bottom line is, if indeed, the gasket that is presently leaking was "right in front of them" while they did the warranty work, it should have been replaced simply as a matter of course. Indeed, the weak link on modern engines has become gaskets and seals. The engine will mechanically far outlast the gasket and seals but the problem is to replace all of them (once they all leak) you have to literally take the engine out of the car and take it apart just to put all new seals in. Please let us know how we can help further on this issue.