To clean any spills in the oven, sprinkle with automatic dishwasher powder, cover with a wet paper towel, let stand for a few hours, then clean with a damp sponge.
Or make your own oven cleaner from 1 tablesp of bicarbonate of soda mixed with a good cup of hot water. Wipe over the whole oven, including the glass door and shelves and the stains will gradually disappear.
Soak oven shelves, trays etc overnight in a solution of biological washing powder or dis washing powder and hot water and next day just rinse
Put one cup of ammonia in a glass bowl, and place it inside the oven and close the door. Let the bowl stay in the oven over night. The next day, use a green scrubby and wipe away those stubborn stains.
Lemon is a great grease cutter. To make lemon oven cleaner, mix equal parts of lemon juice and salt. Apply the lemon oven cleaner to oven stains and let it sit for 15 minutes. Use a green scrubby and rinse and wipe the oven clean.