Theres a good chance the oil galleries are so badly choked with old oil sludge that the oil has been trapped in the head on top of the rocker arms and will have to drain down to get to the sump. Using incorrect grading of oil will cause this and not enough oil changes are the most common cause.
As a guide, my oil level sits halfway between the add and full mark after putting in 4 litres of oil and a new filter on. The hand book states this is where the oil level should sit. But yeah, your oil level should be close to or above the full mark if you're putting in a full 5 litres.
Make sure the dipstick is going all the way in and then wait about 2 seconds before pulling it out. Other thing is whether the 5 litre container actually contained 5 litres and not 4.5 or whatever. Finally, not all engines are created equal - just like hooomans.
Different ? with a warm engine stuff all would be left inside after the sump is dumped.
Either way the opposite is apparent here fellas, if there was trapped oil in a stock engine there would be more oil left in the container, not less, there are no secret holes where oil hides.
It's likely the engine has a different sump (non std) fitted to it, 5 litres for any V6 should be too much even with a new filter.
Either way, check that the dipstick is from the correct engine, if so it can only be due to a bigger sump, which is good anyway.
Think yourself lucky, the cruiser uses close on 11 litres at a change so the only way to buy it is in 20 lit drums, cheaper anyway @ around $85 / 20 lit, while that's diesel oil I doubt the prices would be much different, get together with a mate and go halves in a drum.
So how about the oil filter - some have one way valves fitted to stop the oil draining out so the filter is primed with oil every time you start up and some do not have this valve fitted - though that goes against my argument. Also you may find that some cheap imported filters have a minimal amount of filter paper inside the can needing more oil to fill the filter. (truth or half-truth?)
The strange thing is that the book says the VS holds 4.3 litres including the filter!
Anyway we're p*****g in the wind as 'frenzal_tom' hasn't followed up yet.