Based on probability, you either have a faulty oil filter which is not sealing properly, or there’s a crack or some other flaw in the boss (fitting) on the side of the engine that accepts the filter. Chances are the oil appears when the engine is cold and oil pressure is highest. The oil pressure (which all engines need to survive) is pushing the oil out through the weakest part of this assembly.

It’s not unknown for oil filters (especially cheaper brands) to have basic manufacturing flaws that allow them to leak, so that’s where I’d start my investigation.

Our LPG experts tell us there are a couple of issues that could create such a problem, but the most likely is that one of the control modules in the gas system has been damaged by water intrusion. Take it to an installer experienced with your brand of system.

The Rodeo has a known issue that can cause the petrol consumption while operating on LPG, as you describe. You need to take it to an LPG mechanic, preferably one who knows the particular system fitted to your vehicle who should be able to fix it.