Can't help about the motor noise issue.
Oil change is something you need to do the soonest possible if you don't know how long the old oil is. When I changed my oil for the first time it was really old oil and now I wish I could have done it sooner. Every 10k km or 1 year is good for me. Always with 0w-20 Mobil 1 Advanced Fuel Economy and a Honda Insight oil filter (~13$ CAN).
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Anybody with G1 Insight who got clutch fluid problems?