i have recently purchased a 7th gen honda civic 2005 eagle eye manual transmission. the car is petrol driven. the previous user did not use the oil as per the requirement of the car and poured it randomly. I have the owners manual which says use api grade SG, SH or SJ only. Nowadays, most of the oils are either SL, SM or SN grade. My question to all and especially @Xulfiqar bhai, @goodman2 and @Storm is that can i upgrade to SL, SM and SN grade or will it deteriorate my engine. I had gone through some threads which stated that newer grades lack zddp which is essential for some engines. My cars engine is D16w9.
Yes its correct. my given change intervals were based on same points too.
because 10w-30 & 10w-40 either comes in mineral or semi synthetic. Thats why the intervals of these oils are less.
whereas 5w-30 & 5w-40 comes in fully synthetic and hence their intervals are more.
Also, new cars beats less to engine oils whereas in older engines the change tenors are slightly less.
Mr. A has new car, using 5w-30 and changing it after 8K.
Mr. B has old car, he uses same oil 5w-30 but changing it after ~6K.
and somehow this formula makes sense for Pak. cars. In other countries, the situations can be different.
My point was that you can't generalize drain interval and quality of oils based on viscosities. It could be true for many that lighter viscosity oils are usually better in quality but it is not always true. For example Shell HX7 is Semi-Syn oil having viscosity of 5W30(which is very thin btw) and have drain interval of 4K km. On the other hand Shell Ultra is Fully Synthetic but 5W40 and have longer drain interval than HX7. Some mineral 10W40 oils from LM with MoS2 have drain intervals of around 5K km. If you would search you would find lot of eaxmples that won't support "Viscosity Theory". And btw in Pakistan one should be more concerned about 2nd number in Viscosity i.e Operating temp Viscosity. For Cold Viscosity even 20W would be more than acceptable for most parts of Pakistan even in winter.