Engine is Leaking Oil

[Learning]

My engine is leaking oil quite a bit.

1. Does anybody know if mechanic shops usually charge for finding out where the leak(s) is from?

2. Do engine stop leak additives really help to stop leaks? I tried one recommended by a store clerk and it helped reduce the leaks, but did not completely stop all the leaks. Will a 2nd bottle additive help? I'd like to know what is the best engine stop leaks additive out there? Hopefully someone knows.

Thank you in advance for all your answers!

[Balleristic31]

Don't add anymore additives. Just locate and fix the leak. Is it coming from the front or rear of the engine first of all?

Common m42 leak points are oil pans, valve cover, timing case profile gaskets (mines currently puking from here), and rear main seal. Sometimes oil filter housing but not as often.

[Learning]

My oil pan is brand new because the old one was damaged while my car was being towed one day. So, it's not possible the leak is coming from there, is it?

I see the leak is dripping down from the rear of the oil pan, but maybe it's the oil coursing its way down from the top or somewhere else. Would you say this leak is coming from the front or the rear of the engine?

[bmwm42]

Rear main seal or oil filter housing or upper oil pan

[EyExR]

You could always use a leak detection kit to find out for sure...

But if the leaking is not that bad, I would leave it alone....

[Learning]

Well, it's my fault. The leak was from the oil filter housing unit. When I changed the oil filter days ago, I forgot to put the rubber seal on the oil filter housing cover and so I lost almost all the oil. Luckily, my engine wasn't damage or overheating with such a low level of oil. Could somebody explain why?

Also, when I added a new oil hours ago, I put in too much oil (1/2 quart over the 5 quart limit). Could this cause damage to my engine or will 1/2 quart too much burst the seals and gaskets? Hope someone could explain this.

Thank you!

[roguetoaster]

Engine damage from lack of oil generally takes a fair time to set in. So, if you were not driving it long distances or revving the heck out of the engine you should be okay, if not an M42 is straight up cheap. Also, adding .5 qt of extra oil will not damage the engine at all, after all, track guys/gals routinely add extra oil to prevent starvation. Now 2+ qts extra is another story, and you would probably be looking at a toasted catalytic converter, fouled plugs, poor running, maybe gunked up vacuum breather systems and at worst a holed piston/bent valves or total engine failure.

[AndrewBird]

To find a leak, get the engine as clean as possible. Then drive the car for a few days and take a look where there is fresh oil. With the engine clean, an oil leak becomes pretty apparent.

[LittleEcker]

Along with what other people have said, I'd also like to say that the oil leak is most likely coming from the O-ring check valve. There's a lot of pressure on it, and if the oil is coming from the front of the engine, it would be worth an examination.

I've heard this from a lot of big e30 people. I'm just relaying what I learn at all those e30 picnics.

[Learning]

Sorry, I'm not mechanically inclined and am still learning. Where is the O-ring check valve located? Could somebody please give me a link to a clear diagram/engine sketch with parts indicators of an E30 M42 engine (91 BMW 318i)?

[mccor023]

Another method is to gey the oil leak die from parts store.
Get an ultraviolet light to find the source.
I'm doing that this weekend, need to drive the car a few days to get die through the engine.

[Dj Buttchug]

post good pics of where oil is leaking

[Learning]

Well guys, I thought after putting a rubber seal on the oil filter housing cover, there wouldn't be any leak anymore. I found my car was still leaking a lot of oil dripping on the top of my oil pan from above. And so I took my car back to the same mechanic and after checking he said it was the gasket between the engine block and the oil filter housing (the container that holds the oil filter) that was bad/worn.
Could he be right? And would it be difficult to DIY to replace this worn gasket or seal?
I'm told this gasket/seal lasts only about 200K miles.

[roguetoaster]

It is possible that it is the block to housing gasket. But I would also examine the oil pressure sender on the back of the housing, they can leak in a sneaky way after the plastic cracks and allows oil to seep out of the electrical connector. There is an easy way to check this too, simply unplug the connector and wrap a paper towel or rag around the sender itself, rubber band in place and drive. If it's not the sender its probably the housing to block gasket which is not too hard to replace.

I also just remembered that the dip stick tube has a gasket which often fails and can cause a pretty terrible leak. To check wiggle the dipstick tube, if it more than just budges I would replace the gasket there too.

[Learning]

I forgot to mention that the oil leak began to happen after I changed the oil. First, it was my fault that I forgot to put the rubber O-ring on the filter housing unit cover. I lost a lot of oil, however, later I thought there wouldn't be any oil leak anymore, but the leak is still happening as I had described above. Did forgetting the rubber O-ring might have damaged the oil filter housing unit or it's gasket? I used Purolator oil filter this time. Prior, I used to use Mahle or STP oil filter and there was never a problem. I heard in another forum that Purolator oil filter is not 'up to the snuff' for BMWs. Maybe the Purolator oil filter doesn't fit good enough in the oil filter housing and thus the leak. Should I change the oil filter to STP oil filter again? I actually had the chance to compare the rubber O-ring between Purolator's and STP's and found Purolator's is thinner.