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20w50 + Northstar = trouble


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I started working again last week at a new position in my company where I will report to the office every day - so the Cadoo will not be dry docked for months at a time anymore. While I was on the road giving it gas in the company parking lot (~30mph), the "stop engine" message came on. I immediately shut off, put in neutral & coasted to a parking spot. Checked the dip, and there was no reading. I added 2 qts of oil I borrowed from a co-worker. as it turns out, it was 20w50. the next day I was driving downhill near my house in the morning doing ~40, and the low oil pressure was flickering on again. I drove back home & took my wife's car. I changed the oil immediately that night to 10w30, and all is back to normal. I can't believe that only 2 qts will cause this. It's a shame because the oil in there was only a few months old, and hardly used, but I take no chances. 2 qts of 20w50 was in the car for about 12 miles of driving (hope I didn't do any perminant damage) as for the low oil, I believe I didn't put enough in when I changed it back when, and I might have overfilled it a little with the 2 qts - after 1qt, I still got the flickering pressure light, so I added the second. I have a mat under the car where it has been sitting in the garage, and it was pretty dry - only had a few drips on it - I think just the oil pressure sensor/o ring leaks. The engine is pretty dry too underneath.

If my case halves are bad, would I have seen a puddle? do you all think just the oil caused the low pressure, or can my case halve seals be contributing to lower pressure?

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How long has it been sitting?

I believe you will see this again, but I might be mistaken

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I have been purposely using it the last few months (most 1 week without using max). I took it out a few times the last few months just to get it hot, and drive it. Jan-Nov I used about 1.5 tanks of gas.

I remember you mentioned about your halves leaked when your car sat during the overhaul & went away after getting wet again.

a few years back, I had the oil flicker, but I cleaned the oil & dirt from the sensors electrical connector and I recall the problem went away.

after adding the 20w50, that oil flicker was happening at over 1000rpm - I never heard anyone having the flicker at such high RPM's.

I will try Rotella 15w next change. I have always used 10w30 synthetic & this is the first time this car has seen dino.

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You say that your car has set in drydock for months at a time, a lot. It may have a bunch of condensation in the oil and such. I suggest that you change the oil again at just a couple of thousand miles, and that you watch the oil level for color and using oil until then. There is about a quart below the Add mark on the dipstick before the "Check Engine Oil" warning will be displayed on the DIC when you turn on the key. If you do see that message, put in two quarts of 10W-30 ASAP and check it again. If it's between the Add and Full marks, leave it alone; there is no need to top it off.

If it's using oil when it runs but not when it sits, either it is burning it or it is coming out from the oil pressure lines, probably from the O ring. Some seepage from the O ring is NOT a cause for alarm, and you will see a wet oil pan if you look under the car due to normal seepage, particularly in an older car. You can check for excessive O ring leakage by running the car at about 2000 rpm for a few minutes and checking for more than a drop or two under the car.

Sometimes the oil pressure sending unit gets tired and leaks a little and causes oil light flickering at normal oil pressure. Changing the oil pressure sensor fixes this. It's on the oil filter adapter and is pretty straightforward to change; you probably look at it when you change your oil filter.

Another common problem in Northstars that are babied around and not driven too much is sticking rings. There are several cures for that, but the most fun and least expensive is what we call here "the WOT treatment." I've heard variations called "an Italian tune-up." To me, the best cure for carbon and sticky rings is a fresh oil change and a 500-mile trip at normal Interstate speeds (55 mph - 70 mph, depending on speed limits and traffic). But then, I'm a scenery person. An occasional lead foot with redline in low will keep the rings free and the carbon away; just keep it legal and safe.

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If the sensors are OK (the level sensor would show low level first and then the pressure sensor would come in when there is very little oil left). I

would for safety check the bolt at the vibration damper.

The oil pump is totally depending on the torque there - you need an extra long wrench to obtain

105lbft + 120 degrees (those values are for a 93 Northstar). Have you changed the oil pressure sensor?

I have had sensors in older cars that in fact lost resistance when pressure went up(checked with mechanical

meters) showing no pressure at all at higher revs and then showing pressure again when driving slower. I had

to change the level sensor in one Northstar. I am totally convinced that the heavier oil did not cause any problem.

There are also some temp valves near the oil filter to redirect oil to the oil cooler when hot.

I have no idea if those can screw up the flow.

/Jan L

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You say that your car has set in drydock for months at a time, a lot.

Hi all - I, too, have had my Eldo parked for about six months. I changed the oil about a month ago when i started driving it again (Valv. 10/30) and yesterday the STOP ENGINE / LOW OIL PRESSURE warning came on. Wow, talk about adrenal glands working overtime :rolleyes:

In any case, I'm glad I found this post because I can reasonably expect that this is the case with mine as well. Since yesterday when the message appeared on the DIC it has not reappeared. I am going to change my oil again and wait to see if the message reappears. If so, I will try cleaning or R & R the pressure switch instead of panicking. IIRC (would have to check my records) my case halves were also replaced when she was timeserted a few years back.

Thanks for your help guys.


<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K


As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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