Industrial-strength degreasing foams/sprays might cut down the work if you decide to scrub the oven yourself, but you probably saw the recent news about the possible link between Parkinson's disease and certain chemicals in common refrigerants/degreasers. Granted that research is still in its infancy, but to be safe, it makes sense to avoid them. Some people swear by the effectiveness of this method, but I personally cannot stand the smell of those oven cleaners.
If you also want to avoid the use of those chemical cleaners, use the oven's self-cleaning feature. For our oven, it does temporarily get hot and sometimes a little stinky, but nothing that a few open windows can't fix. Since trying the self-cleaning feature as opposed to the scrubbing with harsh chemicals, I prefer the oven to do its own cleaning. It's less work and more effective for our oven.
If you don't have the paper manual, the manufacturer's website should offer a downloadable version of the manual online.