They make something called Fogging Oil or Fogging Spray that you can spray into the Cylinders by way of the Injector or Glow Plug Holes; Spark Plug Holes if a Gasser. (In the case of gassers I have read of them spraying it in while cranking the Engine.)
It has rust inhibiters and evidently likes to spread out and coat the parts.

I had never new about it until I read it in a post on this forum.

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84 300D, 82 Volvo 244Gl Diesel