The stuff you are describing is called cosmoline, and is a rust preventer that Nissan sprayed in the engine bay before shipping them overseas. I'm sure gasoline will dissolve the stuff but the chance of your engine heating up and igniting some residual fumes from using it isn't worth the risk. Get the stuff I'm using. You can get it at Lowe's or Home Depot for $1/bottle, it actually smells good and does a great job of breaking the stuff down. It's called Citrus All Purpose Cleaner and it's made by Zep. I'm sure there are other brands but this stuff is so easy to use. You just spray it on, put a tooth brush or something relatively soft bristled on it and then spray some water on it. The cosmoline, grease and dirt just run off and it looks great! My back is killing me, but it's finally starting to look good.
