Have water in the oil on my 1993 400e. I'm assuming it is a head gasket, or do these cars have another common failure point that might cause that? If it is a head gasket, the parts store has 2 different engines on file 010591 and 010592. I've looked high and low in the engine bay to figure it out, where is the number located? I just recently bought this car and it doesn't run so I'm slowly piecing it together because otherwise it's in great shape.

Thanks in advance and I look forward to learning on this forum!

Ryan