Oil leaking from oil filter adapter

There are several possible sources for an oil leak in a vehicle. Some common sources of oil leaks include:
Oil pan gasket: The oil pan gasket seals the oil pan to the engine block. If the gasket becomes worn or damaged, it can allow oil to leak out.
Valve cover gasket: The valve cover gasket seals the top of the engine and helps prevent oil from leaking out. If the gasket becomes worn or damaged, it can allow oil to leak out.
Oil filter adapter: The oil filter adapter connects the oil filter to the engine block. If the adapter gasket becomes worn or damaged, it can allow oil to leak out.
Oil cooler lines: If your vehicle has an oil cooler, the oil cooler lines can develop leaks over time.
Engine oil cooler hose: The engine oil cooler hose connects the oil cooler to the engine. If the hose becomes damaged or develops a leak, it can allow oil to escape.
To determine the source of the oil leak, it will be necessary to visually inspect the engine and related components. It may also be helpful to use a dye or UV light to help identify the source of the leak. If you are unable to locate the source of the leak or are not comfortable attempting to fix it yourself, it is recommended to have the vehicle inspected by a professional mechanic.

Easy fix I just did. (replacing the oil filter adapter gasket which is a common leak). Remove the air cleaner tube and housing. Release the tension on the belt. Remove the two front bolts on the air compressor. They are nuts but the stud will come out too which is fine. Under the car loosen the third air compressor bolt. This will give you enough room to loosen the hidden bolt on the oil filter adapter. It only needs to be loosened as the adapter is slotted there. Remove the other two bolts on the oil filter adapter and remove. Replace the gasket and install.

It seems that you have a bad oil filter adapter seal. You can usually pick one up at your local parts store, if not, they may have to order it. To change the seal you must first remove the lines close to block and the you shoul be able to unscrew the oil cooler adapter from the block, may require an allen wrench to loosen. Then you should replace the seal or gasket inbetween the block and the cooler adapter and then reinstall the adapter, reconnect the lines. Be sure to catch the oil in a clean container so you can reuse it to pour back into the block, check the oil level and if at a safe range start the vehicle and check for leaks. If no leaks you should be ready to drive at will.

The fitting that the oil filter screws on to has a hexed bolt at the adapter. unscrew it to remove the adapter

Oil leaks can be a pain to locate so I will give you a few tricks I've picked up along the way for locating oil leaks. Start by cleaning/degreasing the area. You want to remove as much of the old residue as possible. Then you can do several things from here.

1. Purchase and oil dye additive (this additive makes the oil glow when a black light i shined on it) and run the engine for a little while then re-inspect with black light to find locations where dye is concentrated.

2. After cleaning, spray the are that you suspect the leak is coming from with a spray on type foot powder(powder sprays on white providing an excellent contrast to trace leak). Run the engine and follow the oil trail to source of leak

remove the filter and be sure the is a rubber gasket attached, if so rub a bit of oil on it before replacing, being certain that interior threads are clean and not stripped ( if so replace filter) only turning hand tight, no not overly tighten.

2wd Models

1. Disconnect the negative battery cable. Drain the engine oil.
   
2. Remove the oil dipstick.
   
3. If necessary remove the exhaust pipe crossover.
   
4. If equipped with automatic transmission, remove the converter housing pan and the transmission oil cooler line retainer from the bracket.
   
5. On 1996-98 models, remove the oil filter and if equipped, the oil filter adapter.
   
6. If necessary, remove the starter brace and bolt and swing the starter aside.
   
7. Remove the strut rods, if equipped.
   
8. Remove the oil pan and discard the gaskets.
   

To install:

1. Apply a suitable sealant such as GM part number 12346192 or its equivalent to the front cover-to-block joint and to the rear crankshaft seal-to-block joint. Apply the sealant about 1 inch (25mm) in both directions from each of the four corners.
   
2. Clean all gasket surfaces and use new gaskets to assemble.
   
3. Install new gasket and seals.
   
4. Install the oil pan.
   
5. On 1988-95 models, tighten the pan bolts to 100 inch lbs. (11 Nm). Tighten the pan nuts to 17 ft. lbs. (23 Nm).
   
6. On 1996-98 models, tighten the oil pan nuts and bolts to 18 ft. lbs. (25 Nm).
   
7. Install the strut rods, if equipped.
   
8. If removed, install starter, starter brace and bolt.
   
9. If equipped, install the oil filter adapter.
   
10. If removed, install the oil filter.
    
11. If equipped with automatic transmission, install the converter housing pan and the transmission oil cooler line retainer to the bracket.
    
12. Install the exhaust pipe crossover.
    
13. Install the oil dipstick.
    
14. Fill the engine with oil and check for leaks.
    

If it's leaking from the oil filter spacer.( the 2 inch metal ring that attaches to your block, and has two rubber hoses coming out of it, and your oil filter attaches to) There is an o-ring between the spacer and the block. Take off your oil filter, remove the oil filter stud with 1 3/16" socket( or metric equivalent) and the spacer will come off. I found all the auto parts stores around me said that the o-ring was a dealer item. I bought a FRAM PH3387A oil filter and removed the o-ring on that. It fit perfectly, snug down your oil filter stud to specs, then install your oil filter. Double check that the oil filter is not double gasketed, and your are fixed!

The lines can be disconnected from both ends and the bracket removed but to remove the lines from the front (they cannot be removed to the rear) loosen and remove the drivers side engine mount bolt. Use a block of wood between a floor jack and the cast aluminum oil pan and jack the engine assy. up slightly (just enough to "snake" the oil filter adapter lines by the drivers side engine mount. Leave engine jacked up slightly while you "snake" the new lines into position and install the end at the engine oil filter adapter. You can then lower the engine reinstall engine mount bolt and finish the install of the lines by installing the oil filter end of the adapter lines and attach the bracket (that comes with the GM lines) to the block.