Split oil pan?

That depends on what you mean by "split". There are multi-level race pans out there that ridges or plates along the outside of the pan that keep the oil from riding up during hard cornering. Or maybe they're just talking about the double hump pan common to Fox bodies?
 
like a dual sump pan? stock on most 302 mustangs. kinda like this one from canton:

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well my friend changed the oil in his car and it was running fine for weeks then the other day when he was beating on it the #3 cylinder became dead. First I notice that there was water coming out of the exaust and that the spark was ok. When I looked at the sparkplug it looked like it had fuel on it but I din't check to see if it was fuel or not so i'm thinking it was overfilled with oil but don't understand how it lasted for a little more then a month
 
why did he put 2 extra quarts of oil in? i don't think the the extra oil cause the problem. it just would have been thrown around in the pan by the crank. maybe the head gasket was old and it was its time to go? you never said what year engine or miles. i'm sure someone else can explain better than I. crap happens sometimes.
 
well we found 2 extra quarts in the car and im thinking that the pan was split but its sn 84 mustang 5.0 302 with 75k

edit: he din't put extra oil in it i'm thinking that it was just not all drained