I have and currently have a 1 piece seal on my 511ci......i ran into an oil pan leak from under the front timing chain cover..i took off the pan and noticed the front seal coming under the cover had been pushed inward...the one piece pan seal doesn't pull up tight all the way around in other words it has a little slack around the bottom of the timing cover seal ..
what i did to fix this was i took a razor blade and cut off the front seal,glued the gasket to the black pan rails and rear seal using Gorilla snot. did the same thing with the bottom of tinming chain cover piece but filled in the with a heavy does of grey silicon when plaing the pan back on.
"No leaks"...i have used the 1 piece seal 2 times and had the same problem each time...still a great oil pan gasket because of the metal inserts that keep you from squeezing out the gasket on the sides.
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "