According to the service manual, the earlier engines had the tank drain plug (1) in the same place as the newer engines but drain plugs 2 & 3 were horizontal instead of vertical underneath the engine like my 06. I even laid on my back with the service manual properly oriented to make sure I properly identified the plugs. I also gently tilted the bike fore and aft (it was also level on the jack) after each plug drain to make sure all the oil came out. I additionally looked in the tank with a flashlight to make sure it was empty.
As I previously mentioned, something seems screwy with the math in the service manual. It says to initially bring the oil level in the tank to the full mark (that took exactly 3 liters) then start and idle the engine for at least 30 seconds. Thereafter, it should take at least 1-1.5 liters. To me that is misleading. If it takes 5.4 liters for an oil and filter change, then it seems the manual would advise that it would take at least 2 liters to top it off.
Again, when I got my leftover oil from the previous dealer change, it was exactly 3 liters, which means they likely put 5 liters in also and my oil level from that change was about where it is now.
There are a lot of opinions about whether too much oil in the tank is ok but Triumph had the dipstick manufactured with a max mark on it for some reason whether its valid or not. What concerns me (even though my warranty is now expired) would be to roll into the Triumph dealerwith an engine problem and the first thing out of their mouth is that the damage was caused by running way too much oil causing pressure build up, etc. "Yeah, but the book says it takes 5.4 liters for an oil and filter change"........we all know how that goes sometimes.