By Mat79 from LYN forum

About engine oil, iinm, prtn recommend 10w 30 mean that sae is atleast sae 30 rating. Whether 5w 30, 0w 30,it is the same sae 30. The diff is the winter grade. That why its call multigrade oil.

However, for newer car, atleast use 10w grade, avoid any more than 10w if can cause oil easily flow to the engine part durind cold start. Sae 30 is suitable to our climate, and using sae 40(10w 40, 5w 40, 0w 40) or sae 60 (10w 60), wont harm ur engine generally, but it will effect ur fc a bit. 10w 60 is suitable for high powered engine.

Unless u r using old car that consume engine oil, so, 20w 50 is suitable coz thicker oil, less consumable. When someone pointed the graph on the manual, just realise mistakes done on the diagram on the lower side.

Just my advise, there are diff between mineral, semi syn or fully syn, eventhough same rating is the additives added, thats why even mineral can have same sae rating as semi syn like 10w 30. The problem is the additives added wont last long in mineral oil compare to semi syn and overtime, it can change its sae rating coz when heated, the oil become thinner, and when cold become thicker So, overtime, like mineral or semi 10w 30, may change to 15w 20. But semi will last longer its multigrade rating. N fully will last longer than semi.

So, in the end, its up to end user. As long as following the advise as mentioned sae 10w 30@ api sl @ higher, then, it is the safe bet on warranty part. The most important part, check the receipt when printed whether using semi can actually prolong the service interval to 10k@6 months whichever come 1st. If stated like that, then, semi is the best bet coz save up money.

Personally will choose 5w 30 fully for newer engine coz still same sae rating as 10w 30, easier to flow to the engine during cold start, and the price is the same as any fully rated 5w 40, and give a bit better fc, but just a a bit, but, what to loose :-).