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I had a pretty noticeable oil leak around most of my oil pan, it actually wasn't losing much oil overall (I'm not sure how that was the case) but everything around the back of the oil pan and around the sides was always wet with oil. The service shop thought it would be the oil pan and probably the rear crank seal as well, they quoted me a total of $800 to replace both, that was more than enough incentive for me to do it myself! I decided to start with the oil pan so I've searched around and found several write-ups on how to replace it, I knew it was going to be pretty involved but the write-ups I found all had some variations and I found that none of them matched what I had to do for my car with the 3800 V6 and automatic trans. I want to share the steps I went through and hopefully this will save others some time and effort as well, or at least take some of the guesswork out of it. As of writing this I have the oil pan out and am at the point where I'm ready to start putting it back together. I have a couple questions at the end as well....

1) Disconnect the ground from the battery

2) Jacked the car up and put it on jackstands, high enough so I had plenty of room to work under there

3) Drain the oil

4) Remove the exhaust Y pipe from the exhaust headers, in my case the bolts were completely rusted and were essentially one piece with the header flanges so of course they snapped off which meant I had to take the exhaust headers off as well, drill them out and tap new threads, PITA! (I'm replacing both upstream O2 sensors, exhaust manifold gaskets, plugs and wires while I'm in there). If you're lucky you can get the exhaust off from the Y pipe back without dealing with the headers. I had to drop the exhaust from the rear hangers as well to get it completely out of the way, unplugging the downstream O2 sensor first

5) Removed the heat shield around the starter, then removed the starter, disconnecting the wires and taking it completely out.

6) Remove the shield at the front of the transmission covering the flex plate (this is for the 4L60E automatic). To do this there are brackets on each side of the engine block with studs that go through the bottom of the transmission housing. Remove the nuts from those studs, also remove the bolts that hold the brackets on the engine block. On the passenger side the bracket is also pinched between the block and the engine mount. I had to loosen the two bolts holding the engine mount to the block in order to free up the bracket. The front mount bolt was 19mm and the back one was 18mm, the back bolt was also difficult to get at, I used a swivel with an extension and a 3/8 ratchet to get into the tight space. Then there are a couple more small bolts holding the shield to the transmission. *Side note, with the shield removed I got a clear view of the flex plate and the inside of the transmission housing, thank God it was all dry in there so there's almost no chance the rear main seal was leaking, I shouldn't have to deal with that!

7) At this point I had enough room to get at all the oil pan bolts, I removed them so that the oil pan was loose, now this is where it gets fun...

8) The oil pan is above the lower cross member and will not have enough clearance as-is, so the engine needs to be picked up and the cross member dropped. I started by removing the rear transmission mount nut, and the bolts holding each of the engine mounts to the cross member, there are three bolts on each side and I was able to get most with the ratchet, one had little clearance and required a wrench. IMO this was much easier than removing the mount thru-bolts.

9) Moving up to the top side, I disconnected the two coolant lines on the top passenger side, not sure if this was necessary but I wanted enough movement to lift the engine. I also disconnected the intake boot behind the air box. At this point you can make sure nothing else will prevent the engine from coming up, if you have a hoist you can hook up to the engine and pull it up, you should get a few inches of movement out of it. In my case I had to lift from underneath with a floor jack, I had a 16" long 4x4 wood post that I stood up on the jack and braced it against the engine block where the starter was, there's a flat spot there to lift against and it was stable enough. you might also be able to jack under the front of the transmission, I put a jack stand there as an extra safety.

10) Now to let the cross member down (this is where a hoist is ideal to pick up the engine so your floor jack is freed up). I didn't need to support the cross member but I would recommend it if at all possible. I removed the three large bolts on each end of the cross member that hold it to the body near the wheels. Next I removed the bolts holding the anti-sway bar to the frame, there are two bolts on each side at the front. Finally I put a block under the passenger side tire to allow it to drop a little but still support it just enough so the brake line won't be stressed, then I removed the strut tower nuts and bolts from the top.

With the cross member unbolted from the body and the engine mounts, removing the strut tower should allow the cross member to drop enough for the oil pan to clear it and come out. That worked for me, with barely enough room, but if you want more you should be able to drop the driver side strut tower. I didn't do that because that would require removing the master cylinder to get at the strut tower bolts.

Some things I've seen in other write-ups but I did NOT have to do: unbolt the steering rack from the cross member, disconnect the steering shaft, remove the AC compressor from its mounting bracket to get at the engine mount.

Hopefully I didn't miss anything, just make sure there are no hard lines or other hoses/lines getting stretched or kinked when you move the engine and cross member.

Now to the questions:

- The new oil pan gasket I got is an OEM style which is a big plastic piece with a small amount of molded rubber seal around it. Would it be good, bad, or make no difference to add some gasket maker on each side of the new gasket as I install it? It seems like the molded rubber is not enough to seal properly and probably why it's leaking in the first place? If so, what type would be best?

- Where should I be using thread lock during reassembly... oil pan bolts? exhaust header studs? anything?

I also plan to put plenty of high-temp anti-seize on all the exhaust flange bolts and header stud nuts.

Thanks for the help!
 
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