97 Lesabre Low Oil Pressure

[Smith1000]

I have about 167,000 on a 97 Lesabre. Today, on the way home, I noticed it was running somewhat hot, over 200 degrees. When I pulled in the driveway and stopped to get the mail, I noticed the oil pressure gauge read low. As I watched it, it dipped into the red and the red light came on. It stayed running and I drove it the rest of the way down the driveway.

Does it sound like the motor is dying? This car broke down on me last year on vacation and I had to replace the UIM gasket on the road. It had hydro locked. I am wondering if there was permanent damage. Could the oil pump be failing? What should I test? Should I check the cylinders individually? It has plenty of coolant and oil Thanks.

[HotZ28]

A compression test would not tell you anything about the main & rod bearings. You need to install a cooler thermostat & run 10-W-40, or 20-W-50 oil in hot weather. High mileage oil should help also. I run a 160 deg thermostat in the summer & 180 deg in the winter. You can get the 160 deg Stat @ AutoZone (Duralast brand). The cooler the oil & higher viscosity, equals higher pressure!

[Smith1000]

Thanks. I put in some 15-40w this evening. The oil pressure reading may not be correct. It tends to flutter, or skip up and down. I'll see how it does. I may change the thermostat out to a lower temp. Can't remember if I have ever changed it. I don't remember replacing it.

[HotZ28]

You may also have a clogged sending unit, might be worth changing it

[Smith1000]

I replaced the sending unit. The oil pressure reading is now steady, but is about 20 pounds less than before. At start up, it is reading 40 pounds. After driving around and warming up, it is about 20 pounds. Do the oil pumps ever fail in these engines? Otherwise, it runs great. If I step on it, it really takes off. I haven't changed out the thermostat yet, but did pick one up.

[HotZ28]

Change the thermostat and see what you get. The IC gages are notorious for giving false readings, both on oil pressure & coolant temp; so if you want more reliable readings, you could hook up a manual pressure gage and sit it in the cowl below the windshield (taped to the windshield) and take it for a drive. At 167K and prior UIM failure, obviously you have some additional rod & main bearing clearance, but if you haven't noticed a knocking sound, the bottom-end still has some miles left in it. Oil pump failure is very rare on these engines, but like anything else @ 167K, there will be some wear.

[Carwhiz]

Running a cooler thermostat only means the coolant flow opens faster than it would if you have the original temperature installed of 195 degrees. Your ECM is designed to operate at OE temperature for best engine performance. Your gas mileage and performace is significantly degreased until you reach operating temperature. The 3.8L engines are not designed to be ran with engine oil heavier than 10W30.

[HotZ28]

Originally Posted by Carwhiz

Running a cooler thermostat only means the coolant flow opens faster than it would if you have the original temperature installed of 195 degrees. Your ECM is designed to operate at OE temperature for best engine performance. Your gas mileage and performace is significantly degreased until you reach operating temperature. The 3.8L engines are not designed to be ran with engine oil heavier than 10W30.

Installing a 160 deg stat simply means you have full flow through the stat @ 160 deg. The actual coolant temp varies, depending on the cooling capacity of the radiator and driving conditions, such as stop & go traffic. My particular PA Ultra has the heavy duty cooling system option, along with a fan cooled trans cooler mounted in front of the AC condenser. When outside temps reach 90 deg + I install a 160 deg stat and occasionally monitor coolant temps with my scanner. During the day, when driving on the highway @ 70 mph, the coolant temp will maintain about 185 deg; when outside temps drop into the mid 80's the coolant will drop to about 180. With a 195 deg stat @ 90 deg ambient, the coolant measured 205 deg on the highway @70 mph. So, by only changing the thermostat to 160 deg, my particular car runs 20 deg cooler. The PCM will go into 'closed loop' @ 140+ deg and maintain all engine parameters while in closed loop, regardless of whether the coolant temp is 170 or 220, it makes no difference! Emissions might improve slightly @195 vs 180 deg; however, performance will increase @ 180 deg; not decrease.

BTW, I assume you are talking about the universal factory recommended oil viscosity for a new engine, not one with 167K. What is this design limitation you are talking about that would limit viscosity to 10W30? I need to know that, because I have been running 10W40 in the winter & 20W50 in the summer for over 10-years in both Series I & Series II engines (with over 100K) without incident.
(Of course our winters are mild & summers extreme, compared to Minnesota)

[Jrs3800]

Several Things I'd like to bring up here...

The Very bad.. Series II Engines that have had a UIM failure were most likely using a given amount of coolant before the actually failure.. This is very bad news.. Usually the coolant would be burned off in the the combustion process, most of it anyhow.. The contaminants from the blowby process will find its way into the oil and in time the oil takes everything it can take and soon becomes acidic... Once this happens the bearings in the bottom end will pit... From there it goes down hill... Some engines will last a year or two... Some will last a week.. Others if caught in time will go on to live a long healty life... My Original 95 Series II went to 161,000... Had great oil pressure... But my sheer abuse and 6000 Rpm shifts all of its life wore out the piston skirts... It still would cold start with 70-80 Psi and always ran 60Psi hot at roadspeed, 30-35 Hot idle on Mobil 10-30...

Once the Upper intake has gone, or the lower gaskests have degraded several nails are tossed into the 3800 Series II's coffin...


I agree with Hot Z28 on the Thermostat temp... Most of the 3800 Powered cars and for that matter most of the GM cars through 95 can get away with a thermostat of 180F with no issues.. And like stated the threshold for Open loop is in the 140F area.. I Live in FL and run a 180F Performance thermostat in every 3800 I have.. The 1996+ are a little more picky, but 99% of people can run a 180F with no issues or codes.. I have a 180F thermostat in my 03 Bonneville with 0 issues.. The reason the 3800's are ran at 195F is for emissions purposes... You'll get more performance out of a 180F Thermostat, not to mention a slightly cooler 4T60E-4T65E trans...


As for the oil... the 3800's for many years ran 10-30.... I have run everything from 5-30 to 20-50 in them.. I have used 10-40 with no issues in the hot summers.. I used 20-50 in my Van( 95 Pontiac Transport 3800 V6 ) as there was a light knock and low low oil pressure with 10-30... I drove 3000 Miles on the 20-50 with no knock and oil pressure was in the 45 Psi area while running down the road and 20 Psi at idle.. Bottom end was tired and I used the 20-50 to get by untill I could swap the engine..

If you are dropping oil pressure and the engine still runs good its worth a little shot to use a thicker oil to buy some time.. When you get high up into the miles the bottom end will get tired and have more clearance than it did new..

My 03 Bonneville runs about 70 Psi running down the road, and 35-45 Psi hot idle using 5-30 Synthetic.. The New L26 3800 III motor in the van also requires 5-30...

[Smith1000]

I changed the oil filter this morning. Bought one yesterday as I did not have one around when I changed the oil out Thursday evening. The oil pressure came up significantly with the new oil filter. It now reads about 50 pounds at start up. Drove it till hot and it is now reading 40 at idle. With the old filter, it was reading about 20 pounds at idle.

I'll swap out the thermostat this afternoon. Thanks for the pointers.

[auto trainy]

Now I'm confused,your oil filter must have been realy bad that the pressure changed that much or is there a differance in filters that would make that much of a change,I hope I'm not opening a can of worms here.

[Smith1000]

The filter that was in it had been in it for quite some time--probably 10-11 months. We bought a different car when on vacation last year and ended up bringing both cars back. My wife is driving the newer car still and this Lesabre did a lot of sitting since last September. I have been driving it recently though because it has cold ac; whereas the ac quit working in the other Buick that I normally drive. I presume the old filter was clogged--they are both Fram the old and the new.

[Jrs3800]

Originally Posted by Smith1000

The filter that was in it had been in it for quite some time--probably 10-11 months. We bought a different car when on vacation last year and ended up bringing both cars back. My wife is driving the newer car still and this Lesabre did a lot of sitting since last September. I have been driving it recently though because it has cold ac; whereas the ac quit working in the other Buick that I normally drive. I presume the old filter was clogged--they are both Fram the old and the new.

You may have just gotten very lucky.. Never ever use a Fram 3387a on any 3800 V6 or any GM car requiring this filter... They are very poor plain and silmple... at the very least please use an AC Delco PF47... Wix, Puralator among a few others are very good.. Steer clear of the Orange can of death

[Smith1000]

That's not good news. I have often used Fram through the years in both of these Buicks. I'll have to reconsider that as I have never run into this problem before.

[Jrs3800]

I went a bought a Fram PH3387a as i had heard about how bad they were... There was some info on the net( good info at that ) and I decided to take the filter apart... What I found inside was not even fit for my Briggs & Stratton Powered Craftsman Mower... Here is what I found..








These are by far the worst oil filter you could use on any 3800... after taking this one apart I would never use a Fram Orange can of death on anything.. Also note if any of the members have their oil change done at Wally World, you are getting an Orange can of death.. Even the spertech oil filters are far far superior to the Fram..

I work on cars on the side... I actually had a friend bring me his car for an oil change... He handed me a Fram filter.. I made him go back and get a Puralator or I would not change the oil.. Maybe I am picky, but I can't use a Fram Orange Can O Death on anything... Their fuel and air filters are a different story... although I still perfer wix and puralator..