Here is the information about the 4.6 engine oil leakage from the head gasket, Ford's version and the truth. :thumbsup Ford issued TSB 01-21-10 to address the oil leak concern: ISSUE "Some vehicles equiped with the Romeo built 4.6L 2V engine may exhibit an engine oil leak or oil weepage from the cylinder head gasket at the right hand rear or the left hand front of the engine. Oil weepage is not considered detrimental to engine performance or durability. An oil leakk may be caused by metal chip debris lodged between the cylinder head gasket, or by damage to the cylinder head sealing surface that occurred during the manufactoring process." Now the truth. Ford change the gasket design in earlier 98. It is not the fault of the assembler, it was an engineering goof up. The 4.6L engine uses a high pressure oil feed to send oil to the camshafts. This feed is located on the upper right rear corner on the right side and upper left corner on the left side. The gasket that Ford uses is a layered gasket design, the area around the high pressure feed hole is triangle in shape. The gasket in the area of leakage (on 97 and older 4.6L) has all layers open; place three sheets of paper together and that his how the gasket lays on the block. Ford change the gasket in this area so that two sides of the triangle were now crimped together, leaving a small portion that still had opening between the layers...This opening is what caused the oil leakage on the majority of engines. Ford changed this gasket to one where the triangle area was completely enclosed, unfortunally these gasket still allowed the oil to seep out. How do I know? Because I repaired a Expedition with a recall; some goof at the truck factory put straight coolant into a small number of engines. Ford sent out a kit which included two new heads and head gaskets (the partailly enclosed triangle area)when I got done with the repair, oil poured out of the right side of the engine. Going back to the older style gasket fixed the oil leak. This was around August of 1998. It took Ford three years to redesign the gasket. They went back to the fully open layered design and change the the facing material on the steel. Most 2001 Mustangs, Crown Vics and other mod motors vehicles with engine built in late 2000 (August or later) should not have the oil leakage problem due to the head gasket design. If you have a 01 or newer and have a oil leak (the leak happens primarily on the right side) and is located above the starter on back of the head then the leak may have been caused by debris as Ford states. I personally can't recall replacing any head gasket on any mod motor newer than the 2001 models. I would consider oil leakage on the intake valley side to be normal as long as it not dripping and is not on the left bank. The reason the left bank usually doesn't leak externally (like the right side) is because the oil will leak internally into the timing chain area. The quad cam motors don't seem to have this problem beacause the gasket is a different design then the 2 cam motor. I have done around 35 right side gaskets under warranty and maybe 6 total for left side leaking. Ford change the way they want the techs to replace the head gasket late last year. They now want the engine to be remove from the engine compartment. I used to be able to replace the right side only and just make the factory time. Now with removing the engine I can't even come close to the factory time!
The head gasket can be replaced in the vehicle on Mustangs, but this is one operation were its takes less time to remove the engine. On the couple that I've done I removed the
trans and clutch first (all so far have manual
trans) it takes about two hours to remove a 4.6L from the top. If its a pay job expect to pay about 18 hours. The mod motor is a complicated engine and if you are not careful you can make mistakes. One is using anything abrasive on the aluminum head surface, I use a new razor blade held perpendicular to the surface to remove remanents of the gasket. Then using 1200 grit wet/dry sandpaper and cleaning solvent to lower any high spots. Using this method I have NEVER had any come backs with oil leakage. Disproving another Ford statement not to use anything other than a plastic scraper and gasket cleaner. For everyone who read this all the way to the bottom :thumbsup way to go. I hope your more educated on the truth of the oil leak from the head gasket on the mod motor. P.S. I also know why the spark plugs blow out of the Lightning engines, but that should be for another thread as my fingers are getting tired.
attn. Mustangtk of anybody who knows about this 
