I have a 98 Bonneville SLE with a 3800 series II engine, the engine has about 110,000 miles on it and it runs great. Last year at about this time I had to have the upper intake replaced for failure, which was not a big deal because I was just reimburssed the entire amount for labor and parts from GM due to a recall. Now, this year I have a cronic oil leak which I never had before. The oil is coming from somewhere around the underside where the small platic cover is on the bottom of the flywheel between the oil pan and the tranny, but I cannot see exactly where it is coming from. I dropped the oil pan and replaced the oil pan gasket hoping that I would get luck, but I did not...go figure. I was wondering if anyone has had or knows of this problem on the 3800 series II engines. According to a mechanic that I talked to today he told me that the upper main seal is prone to failure. He said he would drop the tranny and fix the leak for $375. Has anyone ever replaced theirs, did you do it yourself, & how involved is it? Did it still leak after repair was complete?
Any help would be much appreciated...

-could very well be the main seal. BUT, before assuming such, here is what I would do:
AND LET ME BE CLEAR ABOUT THIS: IF YOU ARE NOT COMFORTABLE WITH THIS IDEA,,, THEN DON'T DO IT !!

If it were me, I would put the front of the car SAFELY up on jack stands (or ramps, with the park brake set, and triple check to make sure transmission is in PARK), remove that little plastic flywheen cover, and then run the engine while watching for any sign of oil coming from the rear main seal area. (-will need a powerful good flashlight, or shop light)

If it is the rear main seal, then I'm thinking the only way you will actually see it leaking is with the engine running.

MAN BE CAREFUL Those flywheel starter ring teeth could do some terrible serious damage to human body parts Keep your body parts at a SAFE DISTANCE.

Been there, and already done that...cannot see where it is coming from when underneath, its just a small leak, I think I might have found a missing bolt.
If you stand on the driver side, lean over the fender and look down just underneath what I think is some type of cylinder shaped sylinoid, just to the far side where the front exhaust pipe wraps up over the tranny, there is a bolt, looks like it bolts the bell housing to the block, it is at about 12:00....just to the left there is one just like it as well as to the right, I am missing the one on the right. I stuck a piece of wire in the bolt hole to check the depth and it was about 1-1/2" deep, cant tell if there are any threads in it though. It is a 18mm bolt I believe...Can someone tell me if there'* has a bolt in this place. It is a 3800 series II. I think this is my lerak because there is some light fresh oil on the surface and while I had the car runing it appears that there are small air bubbles at the seam. This area is also almost directly above that little plastic flywheen cover.

Can someone tell me if there'* has a bolt in this place????

Well, it'* in the shop right now getting fixed...I gave up. Cold is coming soon, I do not want to be crawling around under it in the snow. I'll post back when it is repaired.

Got a new water pump and oil leak fixed today.Only $461 bucks.My oil leak turned out to be the valve covers.It looked to me like it was the oil pan.The back cover was the bad one.Also could you tell me a little more about the recall on the intakes gaskets.My 98SLE has had three put on.Two sence I've owned it.Thanks SOCLEANONE

I have already change the pan on mine...thought it was the pan leaking...nope! Couldn't get that lucky. $45 down the drain there...it was worth a shot though. I was qouted $375...we'll see, hoping to pick it up from the shop today.
As far as the recall thing goes, I no longer have any of the paper work on it. I believe there was some kind of deadline on it if I remember right. All I really know is that I was sent a 3x5 card in the mail (which almost got thrown away). It had my exact VIN# on it and a 800 number to call I think. I called it and told them what I had done as far as repairs go to the upper intake, they sent me some papperwork, I filled it out and sent it back with all my repair reciepts....about a month later I got a check for $650 :P A full reimburrsment Wish I had that cash now for this repair and a repair I need on my ZR2.
(Damned push button 4WD is junk!
I have been asked several times about this recall, but have no real answers for anyone except for what I remember....Wish I could help you all more, I know what it'* like.
I spent alot of time and money trying to figure it out on my own...

Well, got my Bonne back from the shop today. Seems it was not the seal at all, but a sealing surface in the seal area. There is a mounting flange that is actually part of the rear seal mounting aera. It has a paper thin gasket between 2 casted sealing surfaces and that is where my leak was. Mechanic said he did the seal as long as he was there, changed my oil, tranny filter & fluid, and fixed a broken sway bar mount in the front end for $383.97....and he is a tranny man in a tranny shop. I think I got a good deal, there was no way I could have done this myself with the tools I have. Back on the road

It'* good to hear that there are still some good mechanics out there who aren't just looking to screw someone out of their hard earned $$.

damn, you really lucked out there 383 dollars is an AMAZING deal, for that i would of paid cash with a smile on my face lol.

I was more than happy to pay the $383...but I just wish I could have done it myself, would have only cost me about $50 and some time, then I would have some cash to fix my 4WD in my truck.