Some brands of oil are advertised as sticking to the parts ready for start-up, and there may be something in this (e.g. Castrol Magnatec). I didn't think synthetic oils were particularly strong in this feature; longer life perhaps. I use Castrol 5W-30 Edge (Synthetic) in some cars. Cerato gets Caltex 10W-30 Premium Plus (Non-synth).
I'm a bit of a believer in sticking to the one type of oil for a particular car. I've mostly used Castrol products, quite often 10W-40 or 15W-40, and never had any problems. "Knowing what I now know", I would probably have used 10W-30 for my 10 year old Mazda 6, but figure it's a bit late to introduce a new grade of oil to a mature engine. I chose Caltex for the Cerato just for a change, also that was the oil recommended by a KIA dealer; readily available for about $35 aqnd seems to do the trick. Recommended change interval is 12 months/15000km or 6 months/7500km under harsh conditions.
We here in Oz pay a lot for cars and car products. Run-of-the-mill oils are about $30 per 5 litres, while Mobil 1 is $95. Single-litre bottles are inflated to nearly double the large-bottle price.
Mobil 1 Engine Oil - 0W-40, 5 Litre - Supercheap Auto Australia