I flushed the transmission in a 2001 Sunfire 2.2L with the Automatic 4-speed. I replaced an aftermarket rubber gasket with the OEM metal reinforced gasket and tightened everything down to 8ft-lbs and still had a leak. I went for 13 ft-lbs (8 is spec from Chilton) and one of the heads broke off. I got the stub out using a bolt out kit and replaced the bolt with one of same size/pitch. I also replaced the OEM gasket with the used rubber one, as i couldn't stop the leak, and I still have a very slight leak (two drips overnight). I would like to figure out the type of bolt I need to replace the temporary one I put in and any insigt into the leak. I don't want to leak the Zinc plated bolt in because I am not sure if it will react with the aluminum over time, plus just to keep everything OEM.

The bolt was about 1" long and is a M6-1.00MM (or at least the replacement is that fits perfectly). It had an integrated washer on the head and was black from some type of coating (this is what I am interested in). It was also very hard as I learned breaking three new bits trying to get a hole in it for my boltout. A GM part # or just a spec would be great. Also info. on how you figured it out.

As far as the leak, the housing and pan are razorblade clean and all the bolts are torqued to spec.