I just took the car out to get it nice and warm, to see just how keen the oil light is to come on (was a nice excuse on a nice sunny day). Strangely - I couldn't make the warning light come on at all today - even though I let the oil temp get to 9 o'clock, and let the revs drop to the point where it almost stalls. However - while I was waiting for the temp to rise at idle, I did check the owners manual which said that when the oil is hot, the warning light might come on at idle and I can ignore it. I should only worry if it's low while driving or drops suddenly.

So - I may replace the sender at some point, but I don't think I'll worry about it too much at the moment.

 

Sean:

Anecdotes are not proof. There are laboratory tests that are highly repeatable to evaluate the lubrication, wear protection, and corrosion protection properties of oils. The reason Porsche recommends synthetics is that they trounce mineral oils on performance. Research has also improved mineral oils. Both will work fine. Stories are interesting, but the objective evidence says the synthetics are better.

 

mineral synthetics or real synthetic? category 5 oils(real synthetics) for car engines are almost non existant, dont think for one minute because you paid $100 per litre(exageration) that you are getting anything but mineral based oil. we have a supplier of category 5 oils and at $860 per litre are you going to buy it? i think not. they are not even suitible for engines. category 5 is real synthetic oil, made by man is a test tube and used in the minning industry for wheel bearings, $140 000 wheel bearings infact. in this application synthetic is the only choice. the bearings can last up to twice the time(6 months thereabout) then a wheel bearing with mineral based oil. it cannot be used under any curcimstances in a combustion engine as the oil breaks down extremely quickly when diluted with petrol(as all combustion engines do).
a magazine in australia resently did a timkin test on 14 or so oils picked out from a local auto accessory shop. one of the worst results were the mobil synthetic followed by syn S. the tests were fair and exact with every oil. each had a roller bearing preloaded in an oil bath with constant oil flow. the only thing keeping the bearing from metal to metal contact was the oil film in between. these were also repeated tests. there were mineral oils that out performed the synthetic oils. how could this be? what a shock.
i really dont mind which oils you use in your car, but i urge you to do your homework. do some research. dont just follow the leader because "i have a mate that says his car runs better on the stuff". well we have plenty of customers that have used "Synthetic oils"(mineral based) which cause the car to leak more oil, be noiser the instant the oil was changed out, gone through more oil during oil changes and had more wear while on these magical oils. its marketing. if a company such as exxon mobil(just an example) can triple there profit without doing as much but use additves, which cost so much less then you realise, why wouldnt they? i know i would if i were in there position. its called in the buisness of making money.
you are right Springer 3, research has improves mineral oils but unfortunatly some oils are being formulated to suit newer generation cars with certain additives, and the older oils which had certain additives to suit older vehicles are becomeing harder to obtain.
"synthetic" oils in the right application work very well, "sythetic oils" in the wrong application dont work well.
sean

 

How is working on these cars for over 20 years an 'anecdote'? Quite the opposite I would have thought. This is working 'at the coalface' on cars that are driven daily and on the track.
On the contrary laboratory tests are often suited to the person paying the bills or they are doing their own tests. Can you imagine the results saying 'Well actually our *synthetic* oils are not as good as we thought but we're going to sell them anyway for more than you'd pay for an oil labelled mineral?...No? Me either.

 

Dave,

How's your oil pressure?

Kevin

 

When driving, fine - hits 5 by 3K rpm I think. It's only at idle it's low - barely above 1 at normal temp and probably lucky to hit 1 when oil temp is 9-10 o'clock.

 

Dave,

FWIW mine is exactly the same as yours. I had JZ change the oil pressure sensor at the last service just to be sure but it didn't make a bean of difference. My light occasionally flickers if the oil temp is high (10 o'clock) but it rarely gets there unless I'm stuck in a traffic jam. I just try to keep the revs up a little beyond tickover to maintain the pressure if it starts to happen. Otherwise the pressure is good - towards 5 when over 3k and generally a bit above 1 on tickover. I'm running Magnatec 10W/40.

Regards

Dave

 

Thank you Jet 951 for your comments on oils as they corroborate what I have suspected all along. I'm usually on the 993 site and everyone is patting themselves on the back for knowledge of there cool synthetic oil but also expecting to do a topend rebuild at 60K mi. I'm with 20/50 dino and I expect to get 200K+ out of my engine.

 

I booked the service today - although it won't happen until the week commencing 20th May. I mentioned the oil warning light, and the mechanic will fit an oil pressure gauge and see what the real pressure is.

So - let's hope my engine doesn't stop in the next month!

 

That magazine (Street Commodores) also (to their credit) published a retraction stating they had no idea what they were talking about when it came to testing motor oils. I don't know what the lead times are for the magazine but the fallacy of their testing was pointed out to them in May of 2006.

 

Dave, I don't think this is anything to worry about if you are not noticing any other problems. Mine was the same as yours before all the modifications - and others here have a similar situation. Wise to get it checked at the service just for safety's sake but I would say don't worry.

 

Dave, I had this problem a few times. If i came to a stop the oil pressure would drop to 0 and the warning light would come on. But then when I drove off the pressure went back up and the light would go off. This only happened intermittently but after I had a service and changed the oil to magnatec 10 40 i never had the problem re-occur.

 

Hello all,
1989 964 C4 122000miles
I guess I'm still looking for another solution other than an engine rebuild to replace the oil pump. My oil pressure light comes on at idle and goes away when I get going again. Had the sending unit replaced, changed to dino20W50 oil and had my mechanic hook up his mechanical gauge on the engine and still read below 1mbar at idle when hot (same as instrument gauge inside the car). Mechanic's only solution right now is to replace the oil pump which will be around 40 hrs of work and a 10000$ CAD bill...Very frustrated here, since I've only had the car for 3 months and have put in 6000$ in it already (after purchase price of 25000$)!....I guess these forums are good to vent off sometimes! Does anyone have any other less expensive solution I should look into?...Right now selling this car at a huge loss seems to be the only solution for me!

 

Have you checked the oil pressure relief springs? Maybe one is stuck open a bit?

 

"My mech can drop the engine, rebuild it, re-install it all in a weekend and it would still be less than $10000" ........Does he work nights, or, do take-aways.. ???
Ciao
Charlie