I'm not a big fan of Armor All, or at least their old products. I have always liked Black Magic for interiors and rubber/plastic type parts. It seems to hold the shine longer.
Honestly I don't own anything anymore that I would show off the engine so I don't do alot of detailing under the hood now. When I did it was a good LOW PRESSURE spray and some cleaner (simple green or whatever you like). Wipe stuff down with some rags since the spray alone wont get it all and damn sure wont get the nooks and crannies. Then once that is all cleaned up, I would spray with whatever product you want to use for shining things up, be it Armor All, Black Magic, Company X's Special Sauce (yeah I made that up) and wipe again. Should last for a week maybe before it dulls out. Now this was for newer vehicles with lots of plastic parts. If its older stuff where everything is still metal parts then just clean like above and use something like spray wax or detailer (if painted).
If it wont go...force it.