Al ot of people take their car to mechanic's to do oil change on time or over time, and almost all mechanics put in 5W30 oil, synthetic or what ever,
Here's my suggestion to you:
Summer time and spring, Start putting 10w30, (10w30 is thinker) and keeps the engine cooler and runs better. The oil travels up easily and even if you pass the limited 3 months of 5000 km, its ok,
or
you can use Locus Engine Treatment(found in Canadian tire) or auto part stores with your 5w30 during summer only...
During Winter, add 5w30 only, engine warms up faster, runs better then if you put 10w30 in winter.
Maybe you should read more about oil, so you can understand its properties and design, plus don't you think the manufacturer tests their engines with different oils? I would suggest that they are considerably mpore knowledgeable then you on this subject!
Change the oil every 3K miles, change the timing belt now, and the plugs, belts, and hoses while you are at it. Change all the fluids weather it needs it or not....including the tranny and the brake. i used to do like this and it works better for me