Well... Engine oils are a never ending debate; and most of the times, there is never a clear winner, still... Let's take another example (although it's totally irrelevant here, the thread is for 1KR-FE and 1NR-FE, but still):
As per https://www.honda.com.pk/parts/index.php/products/bycategory/6 , HONDA ENGINE OIL (3.7L) SN 0W20 is there, and is applicable for Models: Civic 2016~ , City 2017~ and BR-V 2017~
In case of Civic, it is (or may be) acceptable, since it's a newer model, new generation, new technology, newer engine, etc. However, in case of Honda City here in Pakistan, does the same 0w-20 applies?
Current generation Honda City in Pakistan, is the 5th generation globally, and was launched almost a decade ago.
Until 2017, 5w-30 has been in use in Honda City, then since last year, why they switched to 0w-20 when nothing has changed; the engine, it's metallurgy, design, engineering, etc.?
In these last 10 years, engine has not changed, technology, metallurgy, etc. for 1.3L L13Z1 i-VTEC, 1.5L L15A7 i-VTEC and 1.8L R18A i-VTEC are almost same (please correct me, if I am wrong). 02 of these 03 engines are currently in use / operation in Honda City here, then why switch from 5w-30 to 0w-20 now (since 2017)?
And specifically speaking, if 0w-20 is the OEM recommended engine oil grade for 1.3L L13Z1 i-VTEC and 1.5L L15A7 i-VTEC since day 01, and has been clearly mentioned in car manuals in USA, Japan, etc. then why Atlas Honda did not recommend it since 2009? in the beginning? why they realized it last year, to switch to 0w-20 from 5w-30? (I personally think, its nothing more than a marketing gimmick, or draw more money from pockets of people)
For newer engines, which have been developed in very recent years, I think one can blindly use 0w-20 or any other grade which OEM recommends. However, for older engines or old technology, one should play safe and either stick to the OEM recommended oil grade or move towards thicker ones with the passage of time; but on requirements basis (like in case of oil consumption or burning, etc.)
I suppose, switching from slightly thick / thicker OEM recommended grade (like 5w-30 or 10w-40, etc.) to a thinner oil is not a wise decision.
