Its a 88' 351w that has been sitting for 6 years. I just replaced the oil, oil filter, a/t filter and fluid, water pump and coolant system. i drove it about 40 miles and now its smoking from the rear driver side near the spark plug, but its not the plug. it smells like burning oil. i tried cleaning off the general area with engine degreaser, but it doesn't seem to do the trick. Looks like it's leaking oil from somewhere and then heating up and burning on the block. what could cause this? any ideas? bad plugs?