step one is to clean the oil off with a good degrease solvent like several engine wash products,like GUNK , or most auto supply stores, and large groceries, sell good degreasing solvents in gallon containers or even hot soapy water with something like dawn dish washing detergent, followed with a pressurized hose several times, then put the car up on a lift and inspect it with a strong light from both over and under and have a small mechanics mirror available. if you locate the leak you can usually find a way to fix it, but without knowing the source your at a huge disadvantage....
Now naturally the area of the engine will tend to limit the probable suspected sources, but most oil leaks occur around oil pans, timing covers or valve covers
the first step in fixing any oil leak is finding the source, of that leak, theres several suspects on the rear of the block. you'll want to verify whats leaking, potential sources, the rear intake gasket, the oil pressure sensor and the rear main seal are fairly common.
a rear main seal installed facing the wrong direction , the wrong oil pan,gasket, being installed incorrectly, the wrong oil pan, gasket ,the wrong oil filter, the wrong oil filter adapter, or improper installation, or forgetting to connect or loose plug in an oil passage jumps to mind
theres lots of guys that spend days trying to stop leaks the the threads or connection plumbing on those sensors all to no gain, simply because its RARELY the threads that leak, its commonly the sending unit itself that defective and leaking internally,or externally, swap it out and when you install the new version coat the threads lightly with high temp silicone
one old trick is to clean the area with carb cleaner , that tends to leave a dry surface and then dust it with talcum powder , use a strong light and have a buddy spin the oil pump, or run the engine while the cars up on a lift or jack stands , helps, tracks in the talc dust , you applied make it easier to find the source
look at
front/rear intake manifold seal
rear cam freeze plug
oil passage plugs
oil temp sensor
oil pressure sensor
pressure sensor threads
oil pan gasket
rear main seal
oil filter adapter
oil filter
valve covers
timing cover
fuel pump area
distributor base

this INFO IN RELATED THREADS MAY HELP locate the source[/color]

[color=#400080]Be sure the lip seal is positioned leaning inward towards the front of the engine, and the rear seals off-set from the main cap parting line by about 1/4" to reduce the tendency to leak oil


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viewtopic.php?f=54&t=3084&p=8194&hilit=rear+seal#p8194

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http://www.superstreetonline.com/techar ... index.html

viewtopic.php?f=54&t=1396&p=3221&hilit=+switch#p3221

http://forums.hybridz.org/showthread.php?t=126081

I will mention a possibility I have seen several times after an oil changes, sometimes the old oil filter seal will stick to the base of the adapter, on the block, instead of coming off with the old filter. If that happens the new filter can be screwed into place on top of the old, remaining second duplicate seal ring but it will not seal correctly. Usually it will leak as soon as oil pressure is applied to the dual seals, when started, but it is possible it will remain sealed well enough to go a several miles before it fails in rare cases. The filter would be the first thing you check, if you see two seals when you will need to remove the filter and reinstall it or get a new filter depending on the seal condition, ,if your getting oil coming from the distributor area it could be a leaking rear intake manifold seal OR a defective oil pressure sending unit, as these frequently leak oil when they fail, and I'm not referring to a few drips, a constant spray or stream of oil that will allow the pan to go dry in under 15-20 minutes is common when these fail.

Im always surprised at the number of newer guys that don,t realize that one of the forward facing bolt holes intersects the fuel pump push rod guide hole in the chevy block, IF your not using that hole for the old style front motor mount you need to get a 3/4" 3/8NC bolt with THREAD SEALER on the threads installed in that hole or that hole will puke oil constantly at any rpms over idle speeds,but don,t place one in that threaded hole over 3/4" long or it might bind up the fuel pump push rod

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the threaded hole might have been plugged with paint, a bolt or sealant that just is no longer there, I have seen several blocks with that hole plugged with a thumb full of silicone thats been painted over, and theres was rather obviously no bolt sealing it, but a 3/4" 3/8"NC bolt with sealant on the threads and a star lock washer is really required if your doing it correctly
You first have to clean, and degrease the block with a good engine cleaner, spray gunk, and a local car wash with a wand you can use in the engine compartment is a good place to start, when cleaning off and engine to locate the source of oil leaks,youll want to get it completely clean and get it dry. Chalk dust ,or body talc powder or even baking flour in a squeeze plastic bottle like ketchup is occasionally found in restaurants in ,can catch the beginnings of a leak and really help you spot where it is coming from.

IF ALL ELSE FAILS,
theres kits that use UV dye and special light to locate leaks

http://www.amazon.com/Tracerline-TP8621 ... 487&sr=1-2
Typical leak spots are:

Oil pressure sender
rear main seal
front & rear intake rail seal
oil filter seal
rear cam freeze plug
valve cover breather grommet
bent pan or oil pan gasket
front cover seal
valve cover seal
front crank seal
oil filter adapters
oil filter seals
oil coolers and lines
upper pass engine mount bolt hole (shown above)
fuel pump hole.
A fairly complete list but there are other less common ones .

keep in mind theres two distinct sbc gasket thicknesses,



btw be sure its oil your seeing leak, before blaming the engine and not transmission fluid,or brake fluid, because thats obviously going too be a different source

Good advice.

Now, you're not gonna believe this but my 26 is supposed to leak oil.

ok first step in locating a leak is to change your oil filter, and verify the oil levels correct,, most Chevy v8 engines will leak, or smoke or run badly if grossly over filled with oil, or run low oil pressure if running significantly lower oil levels than 4 quarts, and make sure you use a quality oil in the 10W30 range as a start point, and use a separate oil pressure test gauge to verify what your true oil pressure is really .
next you'll want to locate the leak, that's usually best done after a trip to a local , drive in u-wash wand ,car wash if its a available, then putting the car on a lift or at least up on sturdy jack stands

obviously once the leaks located the cause needs to be repaired, if you have low oil pressure indicated once the engine heated up but good oil pressure when cold theres a good chance, some factor in the gauges changes due to heat, and sensors or gauges are suspect, until you prove its not sensors or gauges, a change that radical in oil pressure is rarely a mechanical issue, example if your engine reads 45psi cold but drops to 5 psi once hot but theres no knocking or clicking sounds from the valve train and if your reading 5 psi once the engines hot try dropping in a quart of oil and restarting the hot engine to see if theres a marked change in your indicated oil pressure reading.