These engines have a ratcheting tensioner. If this engine had many more miles then I would change the chain because the engine is apart. With such low mileage and apparent frequent oil changes, I would replace the chain if close inspection warranted. I will be shocked if it does.

Your description sounds much more like what would be expected from a 104 engine, but it could certainly happen to a 103. Since you have maintained the cooling system AND the oil is apparently coming from the head, then you are probably correct.

The thing to do is wash the area THOROUGHLY and ensure that the oil is coming from the head gasket before attacking this job. Have you checked the transmission fluid level to ensure that you are not getting A/T fluid in the coolant?

Good luck,