Oil use - peculiar pattern

[zcacogp]

Chaps,

My S2 has always used a bit of oil. It's been an annoyance but I've lived with it. I know it leaks a little from the area underneath the oil filter/oil pressure regulator/oil pressure sensor but I've never got to the bottom of precisely which bit is leaking. I changed the cylinder head recently and thought that that may solve the problem but it hasn't.

However I have done some more careful investigations into how much is used and when. And I have found that the use is not at all consistent. I've used the car a lot recently and discovered the following;

- Long weekend away in Norfolk, approx 550 miles driven over 4 days, mostly two long journeys (there and back) but some short journeys while where. All driven fairly gently (wife in car). No oil use at all. (Yay!)
- Long weekend away to Spa and back. Approx 650 miles driven over 4 days, mostly two long journeys and only one short journey done while there. Driven hard and one long journey was on a notably hot day. Oil use = approx 300ml.
- Two days away to Nottingham and back. Approx 400 miles over 2 days, mostly two long journeys. Driven gently, mainly in the rain with the wife in the car. Oil use = approx 400ml.

I know I need to do some more detailed investigation underneath the car to find the source of the leak but does this inconsistent use suggest anything to anyone? A simple leak I would expect to leak at a constant rate (i.e. 100ml every x number of miles); this is not so. The car doesn't smell of oil and the plugs are clean, not fouled, so I doubt it's burning it. All oil measurements done to a common datum (parked on the same slope, measured to the top of the 'full' mark on the dipstick, with the engine cold.)

All suggestions (and suggestions of common leak points) very welcome, thanks.


Oli.

 

[Gordon Attar]

Most of the Porsche manuals (can't remember my S2 manual) state oil use can be as much as 1 litre per 1000 miles.

If you haven't got a big puddle on the drive or in the garage. Or a load of smoke and or black "stuff" all over the rear bumper.......

Then stop worrying. ....... ...

 

[robdimond]

Oli,

I've noticed the exact same sort of pattern and have a similar oil leak from the oil pressure sensor area. A small amount of oil collects in the undertray. I degreased and jet washed the area a couple of weeks ago to try and help identify.

Rob

 

[zcacogp]

Rob,

INTERESTING - thanks!

Let me know what you find out.

Oli.

 

[PSH]

according to my official Porsche handbook the oil consumption is 1 litre per 1000 kilometre's , my handbook covers both Turbo and N/A 2.5 cars for 86 which have the same oil consumption figures , therefore I would expect the S2 to be the same. Now regarding my own oil consumption, well it varies considerably and it's all about boost. If I drive sedately which I tend to do a lot more these days oil consumption is negligible, far less than the handbook states, put my foot down with the boost set high (up to double that of standard) and it's appreciatively more although still not as high as 1 litre per 1000km or 600 miles. Oh and I have no oil leaks...yet...

Pete

 

[Tommys86]

Never read the manual - so these numbers are new to me but sounds odd that it's technically acceptable to loose all your engine oil within 4k-5k??

I would say our race S2 goes through quite a bit of oil - topping up "some" probably every race weekend, but she's a trusty old horse who's had (and will continue to have) a hard life.... flat out... it does also have some noticeable "weep points" which are monitored (loosely) that could explain the oil level drop.

My road S2, I've serviced and not topped up for 1500 miles... that said I only check oil level to confirm its up there and crack on! So potentially may have lost 100ml or so?!

Oli do you know what top to bottom of dip stick equates to in ml?

 

[zcacogp]

Tom,

I think that top-to-bottom of dipstick markings is 1 litre, although someone will correct me soon if I am wrong!

I've never had a car with an oil-tight engine (car history comprises 6xVW Golfs and 1x944) so I guess I am just used to topping it up, which is why an oil-tight engine seems like an unattainable dream!


Oli.

 

[Diver944]

Page 51 of the owners manual says it's 1.5 litres from the max to the min of the dipstick. I know my low oil warning light comes on about half way down the dipstick and I have to put 800ml in to fill it up again. The first 200,000 miles of my engine used pretty much zero oil, with the only oil it saw was a complete oil change every 6k miles. However now she is up to 225,000 I have to put 800ml in every 1000 miles - she's getting on a bit now []

I'm looking forward to a rebuild when funds allow and a tight engine once more with some of those lost horses back [8D]

 

[zcacogp]

Smiffy,

Yes I had an idea it was quoted as 1.5 litres somewhere but couldn't remember where. I've heard it said that it's 1 litre top-to-bottom and that seems more consistent with my topping-up.

IIRC you said that you had a rebuilt head on your engine a while back (and that it didn't bring back any lost horses). Is that oil use therefore only due to the wear on the bottom end?


Oli.

 

[Diver944]

Smiffy,
Is that oil use therefore only due to the wear on the bottom end?

I believe so. The headgasket was changed at 210,000 miles as a prevention and the head was rebuilt while it was off, new valve stems and seals etc. Alas, it made not a blind bit of difference to the oil consumption and when it was Dyno'd at the Thruxton Dyno day afterwards it was still well down on power []

When the head was off the bores were inspected and looked perfect so I can only guess the rings are worn or maybe sticking. Hopefully a 'simple' re-ring will eventually restore the engine (along with new bearings whilst its apart)

 

[zcacogp]

Oh. Ah. Hmmm. Interesting.

Remember the discussions about Forte Engine Cleaner and sticking it down the bores? Someone on here (could have been Simon) said that it can release gummed-up rings and cures many many more engines than it fails to cure.

Could it be worth a try?


Oli.

 

[Richair]

I notice that my Turbo uses the most oil during long motorway drives at .8-.9 clicks, but during (very) hard use on track it hardly uses a drop. I rebuilt the head just after I bought it so have fresh stem seals, but it does have a small amount of scoring but shows no sign of smoking. It seems an odd pattern, but I don't let it worry me as it uses only around 500ml between 3k max changes.

I do wonder if some oil finds its way through the AOS during certain conditions...

 

[PSH]

Oh. Ah. Hmmm. Interesting.

Remember the discussions about Forte Engine Cleaner and sticking it down the bores? Someone on here (could have been Simon) said that it can release gummed-up rings and cures many many more engines than it fails to cure.

Could it be worth a try?


Oli.

I can strongly recommend the Forte range, my son uses various Forte products on my car regularly, it can help fix many issues on engines, old or new. I did an oil change a few weeks back, used Forte engine flush first, system cleaner later, this along with the new oil has given me 1 bar of oil pressure back when hot, it's also reduced the bounce on the gauge which I'm guessing is the sender unit, it's been like that for many years...will get around to investigating the cause one day...

Pete

 

[robdimond]

Well I found my oil leak... it is seeping from under the crimp of one of the oil cooler lines and then dripping onto the PAS pump. Given the cost of new lines I think I will get Pirtek to replace the hoses on my existing one. Perhaps the oil thermostat explains the intermittent nature of the leak? Only when the oil gets really hot is there a gush of oil through the cooler?

 

[zcacogp]

Glad you've got to the bottom of it Rob. How did you find it? Cleaned everything and then took it for a drive and saw where it was coming from?

Your theory about it only leaking when really hot is a good one. I fear that my symptoms are not as clear-cut but it's food for thought for sure.

Pirtek will be a LOT cheaper than an OPC. A couple of £20 notes and a few cold beers go a LONG way in my local Pirtek branch on a slow Friday afternoon. (Whereas a Credit card seems to reach it's limit damned quickly in an OPC.)


Oli.

 

[robdimond]

Yep, brushed on degreaser and then jetwash. Then went for a few drives and followed the trail of fresh oil. I bought some crows foot wrenches to get at the oil cooler fittings, looks like a fiddle without.