Oil Pressure Strangeness In Saab 95

If the pressure sensor is replaced I would start to wonder about the oil pump or maybe a faulty oil filter. Sometimes these filters have a check valve in them and it could stick.

The time it takes to throw a fault tells me that the oil gets warm in that time and may thin out, thus causing a pressure drop.

Oil normally thins and you see a pressure drop, but if the oil pump is marginal, thinning oil may bring it to the trip point for the sensor warning.

A cheap thing to do is replace the filter and oil with factory recommended blend and weight.

However, your symptom may improve, but the underlaying problem may not.

I would consult a Saab dealer's technician and describe your plight and ask if there are any known issues with these cars that may lead to these symptoms.

There are also many Saab forums on the internet and usually these forums have a wealth of knowledge to give. Describing your problem to them may result in useful information.

Also, do not overlook having a good Saab technician examine the car.

Lastly, if a technician does confirm imminent engine failure you can always go to the auto store and buy every bottle that has the word Miracle written on and dump it in the engine. At that point you have little to lose, but you will most likely be shopping for a new car or engine very soon.

"... buy every bottle that has the word Miracle written on ..."

... or the word Mystery.

An old mechanic friend of mine once said, you can't get a tune-up in a can.

If you wait long enough, the indicator bulb is bound to burn out.

You did not state how many miles are on the vehicle.

Given the age and not knowing what how well you following the manufacturers maintenance schedule, my first suspicion is worn rod and main bearings.

The engine would not necessarily be making noise but worn rod and main bearings could be allowing enough leakage to reduce the oil pressure thus tripping the oil pressure sending unit.

If not rod and mains perhaps a shorted oil sending unit wire. If this wire gets shorted to ground it will cause the light to come on. If there is a bare spot on the wire it could be bouncing around the firewall area giving the intermittent warning light.

Hopefully it is a shorted wire, much less costly to repair.

Good Luck!

Check first for other issues, like coolant level. It's not uncommon on EU cars to give red warning lights for irrelevant problems, just to get your attention. Anyway "red light" is not enough info for oil pressure. S.M.

If not able to do it yourself take it back to the place that put the gauge on and have them test the pressure. It not going to tell you exactly whats wrong but narrows it down from a mechanical problem to an electrical problem. Also has this problem come after an oil change? The wrong thinner oil may cause it. This is usually not an issue but on older cars where there is wear it could.

Your oil return holes are clogged from not changing your oil regularly...about $800 to have an engine demucked last time I checked....but if you don't fix it, the engine will seize......of course I could be wrong...

If I'm right what's happening is that the oil pump is fine it's pumping the oil up into the cylinder head, but not draining back into the sump fast enough, so after a while the pump runs out of oil dropping the pressure and illuminating the warning light....When the engine is then shut off the oil slowly drains back into the sump and all is fine until the process repeats....You can pull the valve covers and see if there is an accumulation of sludge....Now some people might tell you that you can clean it out by adding a cleaner to the oil when you change it, an oil flush they call it, it might work temporarily but not well enough to keep from turning a bearing, then its all over...

Check the oil pressure sending unit.

Had the same problem in my old 1966 Volvo 122S. Light came on, I pulled over. Towed the beast home. Turned out there was a ~1/4" piece of rubber, origin unknown (oil filter gasket?) blocking the sensor. Removed the trash and drove it for another 100k miles.

After doing some research it appears that the low oil pressure (<6 psi) is somewhat common for these cars.

One thing that seems to be common is the intake screen gets clogged in the engine sump with sludge. The sump or pan should be removed and the screen strainer checked and cleaned as a matter of course.

Used to be a problem with older Rover cars, the fix was to take the oil pressure relief valve off of the pump, stretch the spring by about ½" & re-assemble.

Lots of folk suggesting that there may really be an oil starvation issue and not just a false indication.

Getting an oil pressure gauge on there to see if there really is a low pressure situation or not is good advice too.

It would be nice to know what the ECU really thinks the oil pressure is. Do you have OBDII on this vehicle? If you do then this data can be extracted along with all the fault codes and history.

This schmuttfone app and blootoof dongle lets you read the OBDII data and reset fault codes.

If this lights your wick have a play!!!!

PS

oil pressure parameter is missing. The app is being massaged to remedy the omission soon (apparently).

What a goldmine here of really great ideas and suggestions.

I am also of the opinion that your engine is probably full of dirt and needs to be cleaned out. Assuming for the moment that you are still using old fashioned mineral oil and not fully synthetic, which is a great alternative that will also clean out your engine, so first oil change needs to be made at the same distance as mineral oil, after that you can usually double the mileage between oil/filter changes.

Parallel to that, you need (as already mentioned) to add an oil pressure meter to see what is REALLY going on. It could be a bad oil pressure valve (usually in the filter) or even a bad filter NOT supplied by SAAB. (I had an MAN filter on a Datsun many years ago that gave the same problem, luckily it had an oil pressure gauge. Filter replacement with a Datsun filter fixed the problem.)

Regular replacement of the oil/filter is probably the most important way to extend the life of an engine.

Regular checks and topping up may also be required.

Using top grade oil is the next.

Using OEM filters is highly recommended, not "lookalikes".

Having a 30 mile trip (not 2 x 15!) once a week, reduces the possibility of water collecting in the oil.

Farther is better.

Telling us your mileage, your attitude to oil changes and maintenance philosophy would help us further.....

But if your car has over 100,000 miles, you check the oil only occasionally, only use mineral oil and cheap oil filters from the corner store, you may be looking at a new engine.....as has already been posted.

Now if the engine appears to be full of junk, I have heard of people using a 50:50 mixture of cheap oil and diesel in the sump, replace filter with a new one, let the engine only tick for some hours till it has been at operating temp for a couple of hours at least. Do not drive with the mixture.

Replacing that oil with cheap oil and driving around for an hour.

Draining and replacing oil and filter with best quality components.

I stress that I have no personal experience of doing this.....but according to some mechanics here, it can clean an engine that is not too badly worn already, one that is full of dirt and oil/water emulsion from short journeys (or probably finish one off that is badly worn - also good!!).......according to them, diesel dissolves a lot of junk.......

Can anyone else here support or deny that idea?

The only issue with synthetic oil is that for engines that have significant mileage and time running conventional carbonaceous punch, switching to synthetic tends to lead to oil leaks and seal failures.

I noticed this multiple times before. The synthetic oil does such a good job of removing the dirt and grime that it actually exposes all the weak seals and gaskets and oil weeps through.

Once that happens you pretty much need to clean house and replace all the seals and gaskets and start anew. Not a cheap or easy job.

This does not mean that it will absolutely happen to his car, but the risks are much higher. Once done the engine will live happier and your garage floor will be happier, too.

In my experience, engines that are already seeping oil (and totally banned from the roads in Germany and the rest of Europe at test time anyway. I expect the US is the same) are the engines that get worse with Synthetic.

Engines that are dry (as they should be), remain dry.....

Its certainly worth a try and can extend engine life significantly. I have been using it with 100% success on all my vehicles since 1990 or thereabouts....

Only old VW Beetle and other air cooled engines without a proper filter system may not like it. Maybe someone else has tried it on them?

Over the years, I have seen sludge cleaners of many kinds used. All work. Some better than others. An old Chevy van V8 engine with oil return holes so clogged up that the oil did not drain back to the oil pan until it rose in the rocker arm area to the level of the head casting, and then ran back to the cam area and then to the pan. The engine would always dump a load of smoke on start up, then clear up considerably. Pulled the valve covers and dumped half a gallon of oil out of each one. Simple solution was the pressure cleaner in the back of the truck. Made a huge mess, but cleaned the rocker area spotless. Next pulled the oil pan and cleaned that area and replaced oil pump and screen.

I have seen and used diesel fuel, transmission fluid, mineral spirits, gasoline, (small amounts only, and 10 min. running time), immersion carburetor cleaner ( a Ford V8 with a clogged pick up. No running of the engine on this, just let it soak in the bottom of an empty oil pan, then drained and flushed well.)

All of the attempts worked reasonably well.And all of them avoided a major labor bill to remove an oil pan just to remove some chemically removable sludge.

It is NOT by the book. But I believe that I saved the owners of the vehicles a great amount of needless labor, and money. Just my opinion, for what it may be worth.

Interesting post, how long did you run the engines when using diesel? Did you drive or just tick over?

Some sat at a fast (1200-1500 RPM) idle for 2-3 hours. Some allowed to drive for 15-20 min. at easy speeds. With the transmission fluid, I have actually allowed a driver to drive the car with one or two Qts of trans fluid added to the oil allowing it to be overfilled, and drive it a day or two.

Please remember that these were vehicles that were facing very expensive engine repairs if the cleaning did not work.

I understand.

Thanks for the infos, I have never done it myself, but read and heard about using diesel (the other fluids were new to me) and I was interested in knowing if it really worked.....

Now I know!!!

I have a 1999 9.3. Saab has a history of oil sludge buildup. I flush out my enigne oil system every 1-2 years. I also had a problem with the oil pressure sending unit. Once I replaced that the light has not come back on. On the 9.3 the sending unit is on the back side of the engine, somewhat behing the exhaust. Reachable if you want to do it but make sure the car has had time to cool down.

Since I just bought a SAAB 95 Aero I've been doing lots of research for help.

Here are some of the sites I came across. These 3 seem to be most useful. Some are more useful than others.

http://www.thesaabsite.com/index.htm

http://www.thesaabsite.com/saablinks.htm

http://www.saablink.net/forum/

Check to see if your oil pressure loss happens going up or down hills. In some vehicles the oil pick-up can become uncovered if it is slightly bent and the vehicle's attitude is changed. I would also install a mechanical pressure gauge to verify the fault, as the problem may be a false signal.

Get a oil pressure gauge with a long enough nylon tube to feed it. Long enough to run the tube inside the car with you. Observe the gauge while driving. When the the light comes on, observe the actual oil pressure. Then you will know if the engine actually has a problem. Sometimes the wiring for the oil pressure light may short and give a false indication. Everyone has mentioned things to do if the engine actually has a problem. But, this wouldn't cost very much to verify there is an issue.

Foe anyone unsure about Synthetics, who have heard many of the "Old Wives Tales", here is a link that should set your mind at rest:-

http://www.synthetic-motor-oil-change-and-filters.com/amsoil_articles/myths-of-synthetic-oils/

Where you can read the following:-

Start

Myth #1: Synthetic motor oils damage seals.

Untrue. It would be foolhardy for lubricant manufacturers to build a product that is incompatible with seals. The composition of seals presents problems that both petroleum oils and synthetics must overcome. Made from elastomers, seals are inherently difficult to standardize.

Ultimately it is the additive mix in the oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.

Myth #2: Synthetics are too thin to stay in the engine.

Untrue. In order for a lubricant to be classified in any SAE grade (10W-30, 10W-40, etc) it has to meet certain guidelines with regard to viscosity ("thickness").

For example, it makes no difference whether it is 10W-40 petroleum or 10W-40 synthetic, at -25 degrees centigrade (-13F) and 100 degrees centigrade (212 degrees F) that oil has to maintain a standardized viscosity or it can't be rated a 10W-40.

Myth #3: Synthetics cause cars to use more oil.

Untrue. Synthetic motor oils are intended to use in mechanically sound engines, that is, engines that don't leak. In such engines oil consumption will actually be reduced. First, because of the lower volatility of synlubes. Second, because of the better sealing characteristics between piston rings and cylinder walls. And finally, because of the superior oxidation stability (i.e. resistance of synthetics against reacting with oxygen at high temperatures.)

Myth #4: Synthetic lubricants are not compatible with petroleum.

Untrue. The synthesized hydrocarbons, polyalphaolefins, diesters and other materials that form the base stocks of high quality name brand synthetics are fully compatible with petroleum oils. In the old days, some companies used untested ingredients that were not compatible, causing quality synlubes to suffer a bum rap. Fortunately, those days are long gone.

Compatibility is something to keep in mind, however, whether using petroleum oils or synthetics. It is usually best to use the same oil for topping off that you have been running in the engine. That is, it is preferable to not mix your oils, even if it is Valvoline or Quaker State you are using. The reason is this: the functions of additives blended for specific characteristics can be offset when oils with different additive packages are put together. For optimal performance, it is better to use the same oil throughout.

Myth#5: Synthetic lubricants are not readily available.

Untrue. This may have been the case two decades ago when AMSOIL and Mobil1 were the only real choices, but today nearly every major oil company has added a synthetic product to their lines. This in itself is a testament to the value synthetics offer. But, beware, many of the other "synthetics" are not true PAO (Polyalphaolefin) synthetics (ie: Castrol Syntec, Penzoil, etc...) they are hydroisomerized petroleum oil or an ester based synthetic blend.

Myth #6: Synthetic lubricants produce sludge

Untrue. In point of fact, synthetic motor oils are more sludge resistant than their petroleum counterparts, resisting the effects of high temperatures and oxidation. In the presence of high temperatures, two things happen. First, an oil's lighter ingredients boil off, making the oil thicker. Second, many of the complex chemicals found naturally in petroleum base stocks begin to react with each other, forming sludges, gums and varnishes. One result is a loss of fluidity at low temperatures, slowing the timely flow of oil to the engine for vital engine protection. Further negative effects of thickened oil include the restriction of oil flow to critical areas, greater wear and loss of fuel economy.

Because of their higher flash points, and their ability to withstand evaporation loss and oxidation, synthetics are much more resistant to sludge development.

Two other causes of sludge - ingested dirt and water dilution - can be a problem in any kind of oil, whether petroleum or synthetic. These are problems with the air filtration system and the cooling system respectively, not the oil.

Myth #7: Synthetics can't be used with catalytic converters or oxygen sensors.

Untrue. There is no difference between synthetic and petroleum oils in regards to these components. Both synthetic and petroleum oils are similar compounds and neither is damaging to catalytic converters or oxygen sensors.

Myth #8: Synthetics void warranties.

Untrue. No major manufacturer of automobiles specifically bans the use of synthetic lubricants. In point of fact, increasing numbers of high performance cars are arriving on the showroom floors with synthetic motor oils as factory fill.

New vehicle warranties are based upon the use of oils meeting specific API Service Classifications (for example SG/CE). Synthetic lubricants which meet current API Service requirements are perfectly suited for use in any vehicle without affecting the validity of the new car warranty. In point of fact, in the over 25 years that AMSOIL Synthetic Lubricants have been used in extended service situations, over billions of miles of actual driving, these oils have not been faulted once for voiding an automaker's warranty.

Myth #9: Synthetics last forever.

Untrue. Although some experts feel that synthetic base stocks themselves can be used forever, it is well known that eventually the additives will falter and cause the oil to require changing. Moisture, fuel dilution and acids (the by-products of combustion) tend to use up additives in an oil, allowing degradation to occur.

However , by "topping off", additives can be replenished. Through good filtration and periodic oil analysis, synthetic motor oils protect an engine for lengths of time far beyond the capability of non-synthetics.

Myth #10: Synthetics are too expensive.

Untrue. Tests and experience have proven that synthetics can greatly extend drain intervals, provide better fuel economy, reduce engine wear and enable vehicles to operate with greater reliability. All these elements combine to make synthetic engine oils more economical that conventional non-synthetics.

In Europe, synthetics have enjoyed increasing acceptance as car buyers look first to performance and long term value rather than initial price. As more sophisticated technology places greater demands on today's motor oils, we will no doubt see an increasing re-evaluation of oil buying habits in this country as well.

CONCLUSIONS

Since their inception, manufacturers of synthetic motor oils have sought to educate the public about the facts regarding synthetics, and the need for consumers to make their lubrication purchasing decisions based on quality rather than price. As was the case with microwave ovens or electric lights, a highly technological improvement must often overcome a fair amount of public skepticism and consumer inertia before it is embraced by the general population.

But the word is getting out as a growing number of motorists worldwide experience the benefits of synthetic lubrication. The wave of the future, in auto lubes, is well under way.

End

I hope this will further every ones understanding about the usage of Synthetic oils in vehicles....

Synthetic does a better job of scrubbing away the dirt and grime, which in an older engine may contribute to leaking where that dirt and grime also acts as a barrier.

I have witnessed this behavior first hand on numerous occasions.

Synthetic doesn't damage anything, it just cleanses the engine better and exposes weaknesses in seals and gaskets that have been worn by time and grime buildup.

All of which are indicators of less than good maintenance and which should be fixed no matter which oil is used.....

As I said before, a dry engine will remain dry......internally it will be cleaned up and a lot of dirt will land in the filter, this must be replaced early on for an old engine.....I would say after 1000 miles or so to be safe.....

If I needed to do it, I would simply replace any defective seals and use synthetic, but my engines all have it from new......so never a need.

Anyone not using it is really missing out.....as the saying goes - "you can lead a horse to water, but it must drink on its own!!!"

Many would rather believe old wives tales and never try anything new, I tend to be the opposite of that for anything......Synthetic was for me a 100% good move for the last 20 odd years or so......so its up to the individual to decide - fact or fiction!.....

Why has everyone automatically jumped to the worst case scenario?

He needs to find out if the engine actually has a problem.

Verify the issue and go from there. I am in the engine business and the only thing that needs flushing is crap.

Drive the car with an oil pressure gauge installed and see if the pressure is actually dropping when the light comes on.

Consider this:

1. Owner has already had the sender unit replaced with no change in symptoms.

2. These cars have a known history of sludge building up on the intake screen of the oil pump.

Chances that the oil pressure sender is still the problem is very low. Chances of the ECU causing the fault is also low (they just don't fail that often nor in this way).

This tells me that the odds of sludge buildup is probably reasonably high, but the owner should seek a competent technician to diagnose and fix the problem as this problem is likely to be a little difficult for the owner to DIY.

Consider this:

At 10 minutes per answer, 5 hours has been used to ponder OP's question. In less than 20% of this time OP could have hooked up an oil pressure gauge and determined whether the problem is real, or if he needs to take it to a higher level.

Really? It seems that everyone else is doing the brain work here. The original poster only needs to cherry pick the answers he likes while the rest of us ponder the riddle.

That means the original poster's time investment is next to nothing, which beats mucking around under the hood outside in the cold.

Which, by the way, is 0° C (A.K.A., freezing) at the current moment. ;-)

True, for any one question, but in the community as a whole while I'm a net receiver of information here, (and /what/ information, I'm still processing it all) I'm a net giver of information on other threads. I think you get back what you're willing to give.

By replacing the sensor he proved that the sensor wasn't the problem. The sensor has wires that can short intermittently with no rhyme or reason.

He stated that turning key off and on made the light go out. This could be an indicator that there is an electrical issue. The only way to prove the engine really has a oiling issue is to install a oil pressure gauge and compare.

More likely it is simply resetting the fault and there is a delay and/or a minimum number of times where the pressure drops below the trigger point before the fault is thrown.

This keeps down the number of false positives.

Are you positive about the falsies?

Well, under load or G corner load or up and down elevations the amount of oil at the pickup may not be consistent. I could see where you could get moments of oil starvation, which may not be enough to cause harm to the engine, but could trip a warning light.

Typically, mechanical gauges are dampened to provide the same function. Now days we do that kind of thing in software.

This forum can only offer suggestions. If the OP chooses to replace the 1) oil pump and pick up, 2) engine, 3) car before checking the actual oil pressure, so be it.

Forums such as this are great for telling old war stories. But laced in between are almost always good sound advice on solving the problem presented.