My thought are:

1. If one of the o-rings was badly seated coolant would leak constantly and he would run our of it really fast.
2.I think that it's not difficult to make a good gasket on the old Valley Pan cover,it's easily accessible etc. but...but if OP reused a rear collector manifold gasket with some silicone,there's almost no way to get it right,I struggled to place correctly the Victor Reinz gaskets,one was even torqued with only one hole well set.Thankfully I always double check,I know my own abilities to screw things up the first and the second time.

3. I agree on a point about the correct setting procedure for a gasket maker,did OP do it right?What I think...this isn't a vintage car part that is really difficult to get,WHY don't you get a $90 piece and do it the right way?Wrong place to make economy.Am I wrong?

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e53 '00 4.4i Oxford Green II Freshly rebuilt tranny(2nd one) and transfer case/front shaft
e70 '08 3.0si Sapphire Black cinnamon leather 7 seats
e61 '06 530XI Sports Touring Silver - SOLD