I am talking about 660 cc JDMs (almost all of them have very similar maintenance schedules - if only most people bothered to translate the manuals!), be it Suzuki, Nissan, Daihatsu, etc.
The 3 months/5000 km matches the severe schedule for these JDMs partially - like I said, for the turbocharged versions, the change interval is 6 months for normal, and shorter for severe. In fact, on the inside of the bonnet, you can often find a picture indicating the oil change interval. For example:
Ok, so this tells you (in order) the rpms, the ignition timing, the spark plugs, the oil to be used (plus intervals), the oil filter change interval, and the coolant. In front of oil, you see NA (that's the non-turbo version - naturally aspirated), and TC (that's turbocharged). For TC, you read 6[3] months/5000[2500]km. The numbers in the square brackets indicate the severe schedule. The minimum oil grade that can be used is SG (the viscosity can only be found from the manual, but generally 5w-30 is a very safe choice). Oil filter has to be changed after 10000 [5000] km. Just as an aside, the picture also shows that the coolant is long-life coolant (LLC), and hence would be OAT based - first change after 150k km or 7[6] years, and thereafter 75k or 4 years.
So you see, many times one doesn't even need the manual to be able to do basic maintenance. Yet our awaam does not even bother to look properly. Then they complain that this car causes problems, that car causes problems - cars not properly maintained do becomes games of chance. Barely anyone knows that the PCV valve in these JDMs should be changed once 100k km is approached; those who do know complain that they cannot find it. Well, I can easily it for around 10 dollars on amazon as well as aliexpress. If someone cannot do that, contact parts central - they will get it for you for max 4000 pkr.