Oil held in filter and oil pick up

[MK1RS Bruce]

Hi All

Had a strange situation occur that I am trying to get to the bottom of and thought I would ask here if anyone has come across it before.

Oil change on my Mk1 Focus RS, took the sump Plug out drained the oil left it for 10-20 mins as I normally do so I can be sure the sump was empty.

I then went to take the filter off but couldn't get it off, so I put the sump plug back in and then took another car to borrow a strap wrench from a friend, came back got the filter off and swapped nothing to suggest anything was any different to the 10 times I have done this before.

I then filled it up, it takes 4.25 litres including the filter so I pour four litres in from the 5 litre jug. I then go to check the dip stick and its showing about an inch above the full line.

I then start the engine thinking it must be filter capacity and once it fills up then the level will drop which is does but only by 2-4mm so I am still a good 20mm above the full mark on the dip stick.

So I was a bit confused so I just left it that night and decided I would have a think about it and the following is what I have come up with as potential explanations and I wondered what the opinions were:

1. when I took the filter off some of old oil drained back into the then closed sump

2. Sump is not the same volume as the standard one (sump was swapped in the past for a pattern part)

3. dipstick is not reading correctly (can't understand why it wouldn't as the tube and stick haven't been changed)

4. filter is smaller capacity (it is a short version rather than the long version I took off, but I have used one of them previously and never come across such a discrepancy in volume)

I drained some out the other night to have a look and it did look quite dark considering its run no more than 20 seconds since I changed it so I am leaning towards it being scenario 1. Anyway if anyone has any thoughts it would be greatly appreciated as obviously I don't want to run it with too much or not enough oil.

[LarJammer]

Option 5. Don't worry about it, you know for next time that it takes a little bit less that stated.

[Nads02]

I'd suggest using a 12v oil pump off eBay. Connect it to your battery and it'll suck oil out of the dipstick. Not as much of a faff lifting the car etc and would work for you, but up to you whether you want to do it.

[GreenV8S]

MK1RS Bruce said:

nothing to suggest anything was any different to the 10 times I have done this before.

On the same car? You seem uncertain what the oil capacity is, but you'd probably know that if you're chantged the oil previously.

If it's your first time on this car, the most likely explainations would be that the sump capacity is smaller than you expect or the dipstick is giving the wrong reading.

[MK1RS Bruce]

GreenV8S said:

On the same car? You seem uncertain what the oil capacity is, but you'd probably know that if you're chantged the oil previously.

If it's your first time on this car, the most likely explainations would be that the sump capacity is smaller than you expect or the dipstick is giving the wrong reading.

Its the same car, I have had it ten years and change the oil annually and know exactly the volume of oil it supposedly needs, I even use the same brand of oil each time so I can compare what is left in the jug this year with what was left last year and its almost identical.

I have the old sump I am going to compare the shape and see if that is different or not.

[Desiderata]

I usually drain mine through the sump plug, then wait till the flow has almost stopped before removing the filter ( it makes it less messy as you don't get loads of oil running out of the filter connection ). You always get a second surge of oil out of the sump plug when doing this, more than you'd expect the filter itself to hold, so there must be some held in the pipework/ oilways by the presence of the filter.
I'd guess somewhere between a half and one litre on average.
Your car handbook or a Haynes manual tells you how much oil you need for an oil change and they usually give two separate figures, one with a filter change, and one without. There is usually a bit of a difference. My local motor factor tells me how much oil it will take when I'm buying the oil, I don't know where they get the info, but they're normally just about spot on.

[GreenV8S]

MK1RS Bruce said:

I have had it ten years and change the oil annually and know exactly the volume of oil it supposedly needs,

The design of the sump has changed since the last oil change?

[MK1RS Bruce]

GreenV8S said:

MK1RS Bruce said:

I have had it ten years and change the oil annually and know exactly the volume of oil it supposedly needs,

The design of the sump has changed since the last oil change?

Not 100% sure if the design is different or not but the sump has been changed since the last time I changed the oil. The original was corroded and swapped for a non genuine part so could be a subtle difference in the shape.

[MK1RS Bruce]

Desiderata said:

I usually drain mine through the sump plug, then wait till the flow has almost stopped before removing the filter ( it makes it less messy as you don't get loads of oil running out of the filter connection ). You always get a second surge of oil out of the sump plug when doing this, more than you'd expect the filter itself to hold, so there must be some held in the pipework/ oilways by the presence of the filter.
I'd guess somewhere between a half and one litre on average.
Your car handbook or a Haynes manual tells you how much oil you need for an oil change and they usually give two separate figures, one with a filter change, and one without. There is usually a bit of a difference. My local motor factor tells me how much oil it will take when I'm buying the oil, I don't know where they get the info, but they're normally just about spot on.

I think you might have answered my question, I suspect there was oil held in the pick up and it drained back into the sump when I released the filter, normally I would leave the plug out until I had the filter changed but this time I replaced it before I went to get the strap wrench to take the filter off.

I know the oil volume and the manual adds .25 of a litre for the filter volume, I just could explain why it was above the mark when I refilled it with the usual amount but I think, above must be the reason. I will drain a little more out when I am next in the garage and bring it down to the max mark.

[Boosted LS1]

Well I'm glad that's sorted :-)