Good financial analysis....I used castrol edge, car feel like shit. M7 super street way better.
BTW, I don't know which fuchs engine oil the TS need. So just simply post 1 link here.
http://www.fuchsoil.co.za/Products/TDS/Fuchs - Titan Supersyn Plus 5W40 (505.01) - May08 [FES].pdf
If your car is just an ordinary car with rpm not more than 7.5k, no turbo/supercharger and replace engine oil every 5k km, castrol magnatec is good enough. No need to get something more than RM100 per 4L. Used it on Mivec so many years until sold and has no complaint. To be more practical speaking, if you want an engine can last more than its designed lifespan (like 300k km) without overhaul, then you should use the best oil available. But when you reach that mileage, the money you spent on oil probably can do the overhaul job for 1-2 times. For example, you use RM40 recycle oil (local new engine oil that produced by using used engine oil) for a myvi, 5k replace oil. (300k/5k) x RM40 = RM2.4k. Use let's say this fuchs, (300k/5k) x RM100 = RM6k. Different = RM3.6k. According to top overhaul price at average RM600 and full overhaul price at RM1k, at 100k km do top overhaul, 200k do full overhaul and 300k do top overhaul, total RM2.2k only. You still have extra RM1.4k. Even you do full overhaul at every 100k, you still have RM600 left in pocket. This is provided using expensive engine oil will make the engine last 300k km without the need of overhaul.
Marketing strategy's target is the buyer. Prey for a company is the customer. But not all cheap things are good from the point of economy. Merz is expansive (my brother has E230) but if you drive it for long term (more than 15 years), the cost is way cheaper than a toyota or honda.
However, you might need to check on the cost of camshaft, rocker arms, hydraulic tappets and timing chain and auto tensioning kits... because overhaul only covers main bearings, con rod bearings, piston rings, gaskets, oil seals and valve seals....
You might need to consider wear will be taking place at camshaft, rocker arms, hydraulic tappets and timing chain will be elongated....
I guess the total cost to restore the engine will be more than what you have posted....