I changed the oil on my car today, and decided to conduct an experiment along the way.
The last time I changed the oil I was unable to get the sump plug undone due to lack of appropriate tools and a new sump plug, so I sucked the oil from the dipstick tube using my Pela oil extractor.
I was a bit suspicious that I hadn't got all of the old oil out as I only managed to suck out 3.5 litres or so.
Anyway, fast forward until today as it was oil change time again. I had invested in a better tool to undo the sump plug
, as well as a new one for when the old one was damaged as it was removed.
But beforehand I sucked out as much oil as I could through the dipstick hole. Again about 3.5 litres came out.
I then undid the sump plug (with a chisel tapping around the edge in case anyone asks) and about a further 1 litre of jet black oil came out.
It looks to me like the dipstick tube isn't over the lowest part of the sump, but instead the flat part to the right of the lowest part (when looking at the car from the front) as you simply cannot push the tube in far enough to get all of the oil out.
Also it is worth a mention again, what idiot though it was a good idea to locate the oil filter where it is?
That requires a 32mm spanner in case anyone was wondering...
So, if you are thinking about using a garage that insists on an oil extractor, or you are planning on doing the job that way yourself my advice is don't. Use the proper drain method otherwise you are are just going to contaminate your new oil with a litre of the old stuff.
My engine now runs noticeably more quietly than it did before as well.