Possible Clues:

• Keep properly lubricated if you want it to pay you
• Keep thoroughly lubricated - that's the drill
• Instruction to lubricate one of Mrs Ewing's prime assets?
• Eliminate all friction from fuel source
• Leo will engineer something boring out to sea perhaps
• Nodding donkey shaft
• If it gushes, someone's rich (2 words)
• Apply lotion liberally? It's boring
• Mineral bore, for instance?
• Source of petrol