Its a yellow sticker next to the filler plug that says 'Use LSD oil only', the stickers seem quite durable and are usually still there.
ECU repairs and modifications for Suzukis http://www.rhinopower.org
2006 Jimny, 1.3 VVT, stock
2000 Vitara 1.6 8V, Calmini 3+3, 33 MTs, 5:83R&Ps, remapped ECU
1986 SJ413K pick-up with G16B conversion