I'm trying to monitor my '95s oil consumption and am wondering how much the outside ambient temperature affects operating temp, and thus the level of the oil.

In December I added oil to top off the dipstick and noted the milage. At the time the two red arrows pretty much pointed at each other after getting the car to operating temperature and waiting for the check valve to open. Today, after driving quite a bit the oil temp gage was not as high and the oil level guage did not raise as much. Is this a result of it being much colder today than when I checked the oil back in November and again in December?

Here is a little more background: I bought the car in October 2006 with 108K on the clock. It now has 114.3K miles. I bought the car from a respected Porsche mechanic (it was his car) and it was my understanding that it did not need valve guides when I bought it. It developed a leaky valve cover which I had repaired recently. Prior to that repair I attributed the occational oil that I would add to the valve cover leak and normal usage. I didn't record the amount of oil I have added but I estimate about 1 quart per 1000 miles.

Now that the valve cover gasket has been repaired I am trying to guage how much oil I am using. I've had the oil changed twice in the past 6000 miles. The car drives fine.

Other than oil useage, is there any other sign that indicates valve guide wear? And am I just worrying needlessly after spending too much time on Rennlist?

 

As level determinations are to be made with the engine at core operating temperature and idling, this implies that the reservoir thermostat is open allowing circulation to the front heat exchanger: the gurgling lines confirm this and as long as the thermostat remains open, the oil in the reservoir is effectively constant temperature and well above ambient ..... so dipstick level readings remain reliable.
By never filling to more than mid point on the dipstick, my oil consumption has been ~ 1 qt/5K: in my first season with this car, I experimented with topping to the upper mark of the stick. for whatever reasons, this extra 1/4 qt was repeatedly consumed/upchucked/evaporated/?? ... letting me know to stop adding to the top mark.
I listened ... finally , and am now confident in the actual oil consumption ... oh - and never paying attention to the dash level gauge was another plus.

 

Garth ,

With you 100% . The 911 has a BIG quantity of oil in the system . I would never go over 1/2 way at HOT ildle .
Thing to always remember is that doing an oil change , put six litres in and fire the motor up . Keep adding slowly to start the level to read and then watch as , on idle the temperature /level go up .
Doing track time the idle level needs to be looked at to make sure its not overfilled !
Who likes cleaning the inlet manifold out !!!

Geoff
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KS400200,the oldest 964 on Rennlist,unless you know differently !

 

Thanks Garth! Actually the level never seems to drop past a certain point. Would this indicated that I have a leak somewhere? There are no new drip marks where I park.

 

James,
You have found the ellusive magic point! I wager that if you never fill past that level, your apparent oil consumption will drop dramatically, and be the true oil consumption rate. Excess added past that point appears to be aspirated into the intake as Geoff notes ..... for it disappears more rapidly in the absence of apparent leakage. As mentioned, in my first months of ownership, I kept topping up re the dipstick max ( as with any 'normal' vehicle ) ..... and days later, the level dropped to mid stick: The resulting apparent consumption may drive some to consider top end rebuilds .... I'm cheap and low stress, so left it alone : the result is that the engine is far healthier that one would conclude were 'topping up' continued.
Smart car - dumb operator.

 

Thanks Garth!!!! Part of the issue is that when the oil is at that point, the oil level needle does not go up past the orange point, which has added to my concern.

Thanks for sharing your knowledge with me and the board. This is excellent information!

Jim

 

Jim,
Being one data point does not make it universally true, for others may have differing experiences: for example, my level gauge responds nicely if I fill past mid dipstick; however, with the stick level at the sweet spot, the gauge is as useless as mammaries on a bull .... hovering in the red zone at hot idle, slowly expiring to the bottom when shutting down: a mere token response to kindle any tendency to paranoia.
Others are fortunate enough to have gauges that are responsive: you and I do not, so pledge allegiance to your dipstick

 

+2... On my '88 if I tried to keep it at the top of full I would be adding oil every time I drove it. Found that if I let it drop it stopped at the 1/2 point between full and add and stayed there, never needing to add between oil changes.

I do the same with my '97 993 w/ 70k mi. only I only fill it to the 1/2 way point and that's where it stays. The only drawback is that the oil level gauge rarely moves above the red but I don't worry about it since I check it with the dipstick and pay little attention to the gauge.

 

Hey Garth,

Based on your posts, I followed up with the guy I bought my car from two years ago. He is a 30 year Porsche mechanic and this was his car.

He told me exactly what you said.

If I had continued to top off the oil I would have gone crazy!

Thank you, Sir!

Jim

 

I usually wait until I get no flicker of life from the oil level gauge before I top up. When topping up I aim for the middle level of the gauge.

As red rooster said, there's plenty of oil in the system.

 

+1
.. I got advice on this topic from a top drawer engineer in the UK as the oil level/ dip stick was driving me insane.

His advice was as follows...
The oil level/ dip stick only reads the top litre in the tank , so even if it doesn't read , Porsche has designed it that this will not cause any problems as long as the oil is full to just below the gauge/ stick level. Therefore he recommends not refilling oil until there is no movement shown on the gauge when the engine is fully hot ... Then it's time to fill half a litre again.

It's a pretty foolproof way of making sure you never overfill .


As an aside , a Porsche dealer friend of mine sold a 993 some years ago to a very famous F1 engineer , who promptly over filled the car with oil (from cold) and then rang the dealership complaining that they'd sold him a car that was burning oil
We are not alone !!

 

Has anyone noticed higher oil consunmotion if driving the car below 3000 rpm a lot? I just got religion about keeping it over 3000 rpm and the consumption just appears to have become less. Need lots of miles to tell, but what do you think?

 

I am glad to see this... I've been monitoring my consumption since I bought it and have honestly been afraid I was doing something wrong because it didn't seem to be burning any. Level stayed in the middle of the dipstick for several thousand miles.

 

Doing the same monitoring for the same reason. When engine is highway hot I need to add to the top of the dipstick to get the guage into the upper one third as recommended in owners manual. Think I'll try backing off a bit based on this thread. When you all talk about staying over 3000 rpm are you refering to shift point or constant speed crusiing? Sorry for newbie question.

 

I find this to be absolutely true.