ezza

Can anyane advise please, I have just done an oil change on my Lister Petter LPWS4. The manual states the capacity of this engine as 5.5 litres (excluding filter), before pumping out the oil the dipstick level was on full, after removing about 3.5 litres of oil I was sucking air. The instalation is in a cruiser, and the oil change pump appears to be conected to the sump drain which is towards the back (lowest point) of the engine and the dipstick is prety much in the centre of the rocker cover. I thought it may be possible that there may be 2 litres of old oil remaining in the sump but after changing the filter and re-filling to the full mark I ran the engine for 5 minutes, the oil on the dipstick was clean. I did the oil change cold could this be a factor?