Anything must be better than the base material you have in place so the first thing is to get rid of that then backfill and make a big effort to prevent water getting into it again using surface drains.
A product I learnt from the salt water fisheries industry is called Fish-o-Lene. Just paint it on and leave it the steel goes grey and it lasts a long time. Cats love the smell.
How about a tow start or letting it run down hill. Either method should bring some oil into play before ignition occurs. this can be impartant if the emgine has been idle for a while.