Cayman S 2006 Oil Usage

[prestonchris]

Hi

Just had my cayman in for Major service and and full once over from the porsche specialist , up to this point it was using a litre of oil every 700 miles so i was dreading the results of the once over

BUT

Did the IMS check - Fine
Bore Check all bores - Fine

Replaced Air / Oil separator

I've since drove 450 miles and its used 2 bars on the oil level

has anyone any ideas on what could be causing this ??

Cheers

Chris

[bgunn]

Just because the bores aren't scuffed doesn't mean the rings are necessarily sealing perfectly. Was a compression or leakdown test done? That'll give you a more accurate gauge of ring and valve sealing.

Do you ever see any blue smoke (other than the lightest puff of it when starting from cold)?

[edit] Also, I'd be interested in how they determined the IMS bearing is OK without dismantling the engine. Being a 'later' engine it'll likely have the bigger bearing and thus be OK anyway, but it's not guaranteed.

[Patrick Bateman]

Surely the only way to properly check the bearing is to physically look at it?

[prestonchris]

Apologies my mistakle the IMS wasn't inspected have just cleared this up with the specialist

A full bore scope inspection of the cylinders was undertaken though with the result of - No sign of bore scoring on the cylinders

[prestonchris]

The specialist I took it to is Cath Burrows in Standish , she's well respected and has been working on porsche for 15 years

[andygo]

One of the signs of bore scoring are sooty exhaust tips.

My 987.1 3.4 has always had sooty tips, but similarly so have the various Golf GTi's, Mini's ect that I have owned in recent years. Surely thats just a by product of unleaded fuel?

[Rockster]

prestonchris said:

Hi

Just had my cayman in for Major service and and full once over from the porsche specialist , up to this point it was using a litre of oil every 700 miles so i was dreading the results of the once over

BUT

Did the IMS check - Fine
Bore Check all bores - Fine

Replaced Air / Oil separator

I've since drove 450 miles and its used 2 bars on the oil level

has anyone any ideas on what could be causing this ??

Cheers

Chris

Have to point out you have to be very disciplined in your checking the oil level. If there is any variability in this process you can scare yourself silly by accident.

But assuming the usage is real and not an artifact of pardon the expression sloppy measurement then it can be normal.

IIRC Porsche says oil usage can range down to (or up to) 1l/1000km or about one quart every 600 miles.

While your engine's oil usage is towards the heavy end of the spectrum it falls within the range given by the factory.

Usage plays a role, too. Lots of idling or lots of high RPMs can cause oil usage to go up. (When I hammer my Turbo the oil level can drop nearly as fast as the fuel level. But more sedate driving the oil consumption runs about a quart every 2K miles.)

Avoid overfilling the engine with oil. I like to run the oil level at the max level -- checked when hot -- as I want to ensure the engine has plenty of oil on hand, but I do not overfill the engine at all.

And avoid running the oil too long. The oil collects water -- by product of combustion -- and this water causes the oil to aerate more which results in more oil vapor and this can lead to increased consumption as the AOS passes the oil vapor through to the engine.

Which brings me to... My theory is in most cases increased oil consumption not explained by usage or extended drain intervals and absent any other possible explanations is due to an inefficient AOS.

Even new even when working "properly" they suck at removing oil vapor from crankcase fumes. Some time ago the techs I talked to told me invariably when they had to get at an intake on one of these cars they'd find the intake walls with signs of oil on them. This represents oil vapor that is routed to the intake and returns to liquid form and is burned in the engine.

We have all seen the occasional puff of oil smoke at startup. This comes from just before the engine was shut off some load of oil vapor being passed through the AOS and the oil vapor collecting as oil on the intake wall and draining into the engine while the engine sits and the intake gets heat soaked.

But there is nothing special about just before the engine is shut off. All through the drive the AOS is passing vapor to the engine only in this case the engine/exhaust is up to temperature so the oil burns with no real signs, like smoke.

Do not put too much into the soot at the exhaust tips. Soot is a normal byproduct of gasoline combustion. For every gallon of gasoline burned the engine emits something like 19lbs of carbon, mostly in the form of CO2, but some of it in the form of soot.

Remember too there is one or possibly two converters between the combustion chambers and the exhaust tips. Any excessive soot build up is more an indication of the health/efficiency of the converters rather than the engine.

If the engine was burning copious amounts of oil you see smoke in the rear view mirror when accelerating from a stop and with the sun either low in front of the car or low in back of the car.

At this stage the CEL would likely be on as one (or more) cylinders would be running poorly enough to trigger misfires. Or the oxygen content in the exhaust would be high due to the oil and the DME would be leaning out the fueling to address this and go too far and trigger a fueling related CEL.

[Ozzie Osmond]

prestonchris said:

has anyone any ideas on what could be causing this ??

Mileage?
Number of owners?
How's the car been used?

[Ozzie Osmond]

It seems to me there are two different states which may cause oil consumption,

• A knackered engine, or
• An engine with wider clearances due to either (a) manufacturing tolerances, or (b) wear and tear.

When I bought my car the dealership went to great pains to point out the importance of checking oil level on a regular basis. However, over my 4 years of ownership it has never needed a drop to be added. I take this to imply that in the normal way of things some engines use more oil than others.

I have a friend with an expensive brand new Merc which appears to have a considerable thirst for oil. The dealership insists that it's within the "normal" range.

[Steve H]

I would always look for any increase in use as being a big warning sign, it is possible for one engine to vary a lot from the next one with no consequences other than having to top up more often so if it's consistent it may not be a short/medium term worry.

That said, my 06 S with 75k on it hardly uses a drop, maybe 1ltr between services (10k) and I wouldn't be very comfy using over ten times that amount.

[prestonchris]

anonymous said:

[redacted]

Thanks for all the replies , this is my thoughts as well

The specialist has checked the 3 main things for oil usage , bore scoring , air / oil seperator and RMS leak ,

obviously its an iterative process but I'm loathed to keep just "trying" things, for instance replacing the air oil seperator cost me 120 quid including labour and it obviosuly wasn't that

I was just hoping for some "other ideas"

[Trev450]

In your position and having tried the obvious causes, I would be looking to have a leak down and compression test done next. If there are no signs of burning oil (blue smoke) and no obvious leaks, it has to be going somewhere and that can only really be past the rings and out of the exhaust.

[prestonchris]

Trev450 said:

In your position and having tried the obvious causes, I would be looking to have a leak down and compression test done next. If there are no signs of burning oil (blue smoke) and no obvious leaks, it has to be going somewhere and that can only really be past the rings and out of the exhaust.

Thanks mate , going to ask for that done next

If this is the case then whats the issue with the engine ?? Am i looking at a big bill :-(

[Trev450]

prestonchris said:

Trev450 said:

In your position and having tried the obvious causes, I would be looking to have a leak down and compression test done next. If there are no signs of burning oil (blue smoke) and no obvious leaks, it has to be going somewhere and that can only really be past the rings and out of the exhaust.

Thanks mate , going to ask for that done next

If this is the case then whats the issue with the engine ?? Am i looking at a big bill :-(

Unfortunately you probably are. If there is wear to the piston rings and/or liners then this is a major rebuild. Less so if it is valve related but still would be costly.

[prestonchris]

anonymous said:

[redacted]

Yes I am very aware of Hartech and their expertise but Cath worked at Hartech before starting on her own , she's rebuilt 4 cayman engines this year due to bore scoring , for this amount of oil usage to be down to bore scoring I would think the scoring would be fairly obvious , I can't get the car to Cath for a while so was just trying to extract some knowledge before I saw her , maybe someone had been through my same experience on this forum - its not like its anything I can fix anyway


i do feel that Hartech are looked upon as some kind of demigods on this forum sometimes