Gentlemen, according to the 'pukka' 'book of words' the sump capacity for the 'tin' sump on a 500 is as follows:----During oil-change:--1.54qts (Imperial)--1.85qts (U.S)--1.75Lt. From dry:--1.85qts (imperial)--2.22qts (U.S.). So, as you can see, you get approximately 1/2 pint left in the engine during oil changes. As far as I can see, no 'factory' sump will accept 2,5 litres---the SMALLEST of the Alloy sumps take 3.5 litres. DO NOT try and put 2.5 litres into a 'tin' sump---the crank-shaft will dip into it and start causing all sorts of (probably quite expensive) problems.