I would be doing an oil change and filter asap - as long as there's no other evidence of water getting into the oil.
From what you have said it looks like a prolonged build up of condesation that has never had the chance to evaporate with the engine running at the correct operating temperature/s over any length of time, Starting it and only running it for a short period will not help the situation, once the oil and filter are changed take it for a decent ride and make sure it gets up to proper operating temperature and see what it's like then, if there's still some evidence of condensation after that and everything else is fine then it might neccessitate another oil change to completely flush the system, might also be an idea to change the coolant at the same time.
From what you have said it looks like a prolonged build up of condesation that has never had the chance to evaporate with the engine running at the correct operating temperature/s over any length of time, Starting it and only running it for a short period will not help the situation, once the oil and filter are changed take it for a decent ride and make sure it gets up to proper operating temperature and see what it's like then, if there's still some evidence of condensation after that and everything else is fine then it might neccessitate another oil change to completely flush the system, might also be an idea to change the coolant at the same time.
