If only I could remember where I buried those 20 new Spitfires

[Letum]

They buried plenty of material here in England at the end of the war as well. At the closest bomber airfield to me there is a large magnetic anomaly caused by all the buried metal from bombs, Jeeps, aircraft parts etc. Radios don't work anywhere near it, so it must be very large.
I don't think any amount of grease, oil and warping could save much of it.