I wouldn't worry about the finding Japanese spec for the oil as long as it as the oil has a CF or higher rating. C means Diesel and The second letter is the rating, the higher then letter the better the lab test rating.
I disagree, the higher rating is not necessarily better for your older engine. They have been reducing calcium in diesel engine oils for some time now for pollution control issues and this is bad for our engine bearings.
Toyota diesels of our vintage don't have wear problems with the bore as much as bearing issues, and this is caused by low calcium oil formulation, the use in the OEM engines of aluminum bearings instead of tin/lead and the fact that the 1HD-T engine has a harmonic vibration spike at 2000 RPM that has a tendency to destroy bearings, especially brittle aluminum based ones, by cavitation.
Cañonero, if you worry about glazing do as I did when I first got the truck: drive it fast and hard for a few months. You'll be surprised how well it works after that. Also driving it hot for an extend trip helps quite a bit. Your oil consumption will drop quite a bit after that!
I use Rotella-T 15W40 (not Jaso rated) and have had a 3B that still runs after 700,000 km (the truck is now retired) and it has seen 15W-40 Rotella-T summer as well as winter. That 'conventional' oil is actually flows better than some synthetics in winter!
For my 1HD-T, I upgraded to synthetic Rotella-T 5W40 for winter, and use the 15W for the rest of the year. Also since I got the truck, my oil changes have been extended to an average 12,000km. Seat-of-the-pants wise, the oil feels great much longer than on my old 3B where i could feel a difference after 5,000 km.
With this engine and oil filter (the OEM Toyota filter is dual-cartridge / dual stage internally), it feels perfect for a good 10,000 to 15,000 km. You start feeling the noise and lower performance past that. Also this engine /oil filter doesn't turn the oil black like the old 3B and I haven't noticed any oil thickening until 20,000km (yes, I did go that high with my oil change in my second year, but I racked up 45,000 km that year).
With the dino oil, I do notice some "degradation" (feeling wise) earlier.
As for oil consumption, running it hard after running it gently for a long time will usually get rid of bore glazing. The first oil change I used up one litre per 5,000 km, now its more like 1l per 10,000 km. Basically, I replace the oil when I'm down one liter

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I also use additives under some circumstances. I add CD-2 MAXX engine detergent if I intend to stretch the oil change interval (I got a lot of old-stock, high-calcium CD2-MAXX before they changed their formulation to comply with the new emission control diesel's requirements that came out in 2007). In summer in very hot weather (which is almost never where I live), if I have to extend the oil change interval I will add some Bardahl 'No-Smoke' on top of the CD2-MAXX as it does quiet the engine a bit, especially if I'm going for an extend trip.
There you have it... You just started another lubricating oil polemic
