Grease is a very tacky substance, which means is doesn’t wipe off easily from anything, including plastic. Grease itself is unpleasant, but will also attract dirt to the plastic if you don’t clean it. It’s actually not difficult to remove grease off of plastic, whether it is automotive grease or grease from food. You just have to use a grease-cutting cleaner that is safe for plastic and warm to hot water, as this helps dissolve the grease.
Scrape the plastic with a plastic scraper or spatula to remove as much of the excess grease as possible. If the plastic item is cold and the grease has solidified some, warm the scraper or spatula first under hot water.
Pour grease-cutting dishwashing liquid directly on the greasy area. If the plastic item is small enough, place it in your kitchen sink and fill the sink with hot water. For larger plastic items, use a wet sponge to drip water onto the greasy plastic.
Let the dish detergent sit on the plastic (or, in the case of smaller items, let the plastic soak in the sink) for five to 10 minutes, which is the time suggested by the Mrs. Clean website.
Scrub the plastic with a wet sponge. Add more warm water and detergent if the grease is difficult to remove.
Rinse off the item thoroughly with warm water. If this is a large plastic item (such as a plastic patio chair) use a bucket filled with warm water and just pour this slowly over the item.
Dry the plastic with a towel. Touch the plastic--if it still feels a bit greasy, rewash it with the dishwashing liquid until it feels and looks clean.