Well as a newcomer to extraction pumps I cannot cite a long history of use - but I can confirm that I too check the volume of the extracted oil and I am confident that very little, if any, gets left behind.
And as I change the engine oil at half the stated interval - I really don’t see the problem.
On my old LR’s you had no undertray and could run two wheels up onto an old plank to ensure the sump was “leaning” towards the drain hole then get underneath with ease and filter off, drain oil - drink your cuppa while last drops come out, new washer, replace plug, fill new filter with oil, screw on, fill engine, check level - and job done. Easy.
But doing this on a ZTT with its undertray and low ground clearance is just not the same attractive proposition as on a LR.
So, I lift the bonnet, put in the tube after removing the dipstick, being carful to ensure it goes in as far as it needs to and no more (the pipe on my pump is quite rigid) extract the oil whilst drinking the tea, change the top mounted oil filter (lovely design!) when pump has done its job, check volume extracted and replace with new oil.
What could be simpler or more satisfying?
Am I bothered if a bit of oil is left in there? Not at all because it has only been in there for about half its recommended time anyway.
Besides - by my observations I get out the volume I put in!
But just say for arguments sake I left a quarter of a litre in there (I don’t think I do but let’s play pretend!!!
) then 250ml / 6.8litre x 100 = 3.7%
So that means I would have changed 96.3% of the oil in my engine.
