First step is to make sure the oil is topped off to the full mark, and then start checking it yourself weekly. You don't know that you consumed 2 quarts in 1100 miles, as it may not have been completely full after the oil change (unless you checked it yourself).

Anything up to a quart consumption per 1000 miles is pretty normal. It is higher than many of us would like to see, but it isn't unusual.

I wouldn't change oil to a 40w at only a 35C ambient. That isn't hot. You can change if you want, but it is unlikely to make much difference. At this point you don't know where the oil is going, so I would say it is premature to change oils.

Once you have figured out how much you are using (keep records), then you need to figure out if the engine is burning it, or it is leaking.

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