oil pressure problem part 2

[puma]

Hi guys, a month ago i asked about an oil pressure issue i had and i decided to have a lab analyse my oil to see if i really had an oil problem or if it was a bad sending unit.

here is the original thread for those interested. http://www4.forum.viperclub.org/showflat.php?Cat=0&Number=791100&an=0&page=16#Post791100

I'll try to sum things up. Bought the car during winter and imported it from USA to Canada. Drove the car gently during winter, it probably was around 10-15 deg F when i did (had to bring the car to inspection, registration thing). I basically had almost never drove the car before that. Car started fine and ran well until i got on the highway (reved a little higher) and the oil pressure light came on. I kinda panicked so i waited until i could pull over (10 seconds) and when i finally did, the light came off. Drove off again and the light would come on and off for a little while (another 10-20 seconds). I did not even know at that time there was an oil pressure gauge in the car so i was just looking at the light in the dash. when i finally passed the inspection, the light came on again when i started the car but this time, i saw that the oil pressure gauge was reading 0. I stopped the car right away and restarted it and the gauge was reading fine and the light was gone. This is the only time i have seen the gauge at 0.

So i thought maybe the sender of the gauge is bad and that the light automatically came on when the gauge read 0. By the way, i checked the oil level and it was fine. I changed the oil and both sensors (light and gauge) and for the little drive i did with it the light never came back on. There was no appearant metal on either the oil plug or in the oil itself. While i was changing the oil, i decided to take a sample and send it to blackstone lab.

I just received the results and there seem to be a little over twice the average amount of iron in my oil. So i decided to electrically unplug the sensor for the gauge to see if the light would come on when the gauge reads 0 and it didn't. This mean that i truly had a low oil pressure. Blackstone lab also told me the oil seemed to be something like 20w50, which is way to thick for this kind of weather. (previous owner put that oil in, i didn't know what kind of oil was in there)

What should i think of all this? Could the fact that my oil was too thick cause a low oil pressure at such freezing condition? If i had a low oil pressure, does that mean there is no way it will be a one shot deal? Does that mean a rebuilt? Car is a 1998 GTS with 24k miles. When the low oil pressure happened, engine didn't even change sound and the car still runs perfect. I am not concerned about how the engine is right now cause it runs fine, i am concerned that it might degrade even more.

what do you guys think?

thanks a lot for any feedback or exeprience, great forum.

 

[snampro]

always tell people the year of your car, that's helps sometimes. I see from the previous post its a '98 GTS.

what viscosity oil did you think you were using? if its was cold and your oil was very viscous it could have caused this problem. make sure you use the right oil and quality stuff...

if Tom doesn't post in this thread soon shoot him an email, he's the pipe engineer (jab at mechanical engineers) around here.

 

[puma]

look at the bottom of the post, it is written that it is a 1998 GTS.

i didn't know the viscosity of the oil since i just bought the car, don't know what the previous owner was using. I put 10w30 afterwards.

i am not very familiar here, mind telling me who Tom is?

thanks for your help.

 

[Tom F&L GoR]

Don't get in a panic over 2X the wear metals. Texaco ran 100,000 taxi cab tests in New York city (14 months, average 8 MPH, never turn off) and would see 100-200 ppm Fe. Yes, it is wear, but when you change the formulation or the drain interval, it goes back to normal. All those engines lived still lived a normal length life.

If it is not accompanied with higher aluminum, maybe chromium, or lead levels, then I don't think you have a problem. Oil isn't smart enough to only cause wear with one metal and not others.

No offense to Blackstone, but they can't tell what the "W" number is. It is run on new oils, you cannot estimate it in used oils by looking at the 40C viscosity, and the 40C viscosity changes with time (oil oxidation.) Further, if low temperature properties could be predicted by simple 40C measurements, there would not be two other, more expensive, more time consuming tests to produce the "W" number.

The "W" number is predictor of cranking performance at low temperatures, which is not the same as operating at low temperatures. The 20W rating is good for -15C or 5F cranking. Once it cranks and starts, the oil is going to get warmer. The "W" number is only needed for making sure the oil gets sucked into the oil pickup tube and into the pump. Once in the pump, the pressure on the downstream side will make sure it gets to wherever it needs to. It's the sucking side that is important.

If you would list the actual results from Blackstone we can talk about it more. So far I would guess that the previous owner used a thick oil and also didn't change it on time. If that's the case, your bigger issue is if all oil changes were not frequent enough and you have sludge blobs or varnish that restricts oil return passages (i.e. holding more oil in the heads and less in the sump while driving) or that a blob plugs up the oil screen.

 

[Tom F&L GoR]

PS: "jack of all trades, master at none" engineer.

Buy some brakes and you can call me whatever you want.

 

[snampro]

That's Tom.

when I get a functional diff in my car and recover from the cost of the half shafts I didn't plan for I may just do that.

 

[Freddog11]

Hey Tom, just out of curiosity, if indeed the previous owner did not change the oil on a regular basis and the sludge blobs and varnish you describe are there, what is the solution? Will they eventually dissolve with consequent frequent oil changes or is an overhaul required?

 

[Tom F&L GoR]

I have never seen an oil able to effectively clean up an engine, even with repeated oil changes. Engine flush (something you pour in just before an oil change) either doesn't work well enough to be worth while or if it does work, is so harsh a chemical that it affects seals, gaskets, elastomers, etc.

Varnish is usually permanent. The amber to brown color, or layer if it's really bad, is not going away. On surfaces you can see there isn't much harm, but it is a cause of stuck lifters and pistons rings.

Sludge is difficult to remove with oil changes. It is a "newly formed" molecule; one that is a larger, stickier, more viscous molecule formed by heat, time, and combinations of water and exhaust. You almost don't want to use an engine flush to clean it all at once since dislodging a large amount of sludge can plug up the oil screen and starve the engine.

You could try more frequent oil changes, or use a higher dispersant oil like diesel engine oil. The amount of clean up will be minimal. I wouldn't go so far as to say an overhaul is required without first looking inside (perhaps removing the oil pan and a rocker cover, since that's easy enough.) But at least you prevent reaching a dangerous level of deposits.

 

[puma]

Hey Tom, nice meeting you

I honestly am not to worried about the iron content in the oil, i am more worried about the fact i have lost oil pressure and i am afraid it might happen again. I have no leak on the car by the way.

I really doubt the previous owner was neglecting the car as he was pretty anal about it. I know the tranny was rebuilt so at least it has new oil in there. Don't know about the diff though.

What Blackstone said is that the oil was thicker than the regular 10-30, well just read the report, it is written there.

Basically what i am afraid is that the lack of oil pressure might come again. Could it have been a one shot deal because my oil was too thick and it was too cold? From what i can read, you don't think so. What could have happen then?

here is the report and thanks again guys, man i am happy we got some geniuses around here.

You must be registered for see images

 

[Tom F&L GoR]

The oil looks near perfect. Interesting to try and figure out the comments. Kind of snippy, aren't they?

An SUS of 81 (although they should add at what temperature this was measured) is roughly 16 cSt. If at 100C, then it is in range of an SAE 50. One cannot even guess if it is a new or used 5W-50, 10W-50, 15W-50 or 20W-50 without measuring the viscosity at a second temperature. You might have a clue by measuring viscosity at 40C (typical) but the "W" number is really measured at temperatures below 0C.

I assume they are saying 5W-30 or 10W-30 because they know the engine and specifications.

Iron wear? You could use this oil longer. Perhaps you've sent previous samples for them to assume an average rate? Even so, while most results could indeed be within the range of average, the Zinc and Phosphorus are too different to be the same oil.

The fuel dilution seems high considering there is no water present. In a cold running engine (the oil takes 30-40 minutes to get to the boiling temperature of water) you would see both elevated. If only fuel is elevated, then maybe there is a partially plugged fuel injector and the spray pattern is more like a squirt gun rather than a fine mist. However, both "quick and dirty" tests for fuel and water are not very accurate, and I think Blackstone runs the "Q&D" type test.

The gear drive oil pump can't stop and restart. If you've checked the oil level and the heads aren't capturing a lot of oil, then the only thing that could interrupt oil flow is something in the pan covering the pick up screen. It would only get worse and worse while running the engine, since the suction would keep it on the screen, and probably stay there after shutdown, too. The fact that it comes and goes still argues for an electrical issue somewhere else. Good luck.

 

[plumcrazy]

good thing we got you tom

 

[dansauto]

sounds like the sending units just went bad. What does the sending unit read now?

Tom-I have seen that cars with blown headgaskets ir intake manifold gaskets have some of the cleanest motors. Customers that drove the car a little after the gasket started leaking antifreeze in the motor really cleans varnish (probably also caused motor wear and the oil lost its lubricity) Makes me wonder in ****/h20 injection would be a good thing on occasion to clean out a motor

 

[Tom F&L GoR]

Strange things can happen. The antifreeze is at least 50% water, so that may steam clean parts. However, glycol is easy to oxidize and the anti-oxidants in the engine oil will quickly be overcome and loose the war. The oil will turn dark quickly, thicken, and turn acidic. Incompatibility with the additives and insolubility with the oil will keep the glycol and oil separated, so the oil will become foamy looking and the lubricant properties will depend on whether a slug of oil or a slug of glycol passed through. The acids will pit soft metals such as bearing surfaces. The additives and glycol may clump and plug the oil filter.

I think methanol would be a good solvent for the deposits... and many elastomers, too.

 

[puma]

thanks a lot for the answers. As far as fuel in the oil, i had just started the engine to move it in the garage, this is why i get so much fuel in the oil, oil wasn't brought up to temp but i was aware of that.

I have changed both pressure sensors with my oil change and it didn't happen since then but i drove the car for like 20 miles since that day. I just guess i'll go and drive the car some more to see if the problem comes back.

Last question, from what i can read, there really isn't anything in the system that could have caused a momentary failure of the oil pump or something? Only thing would be if something got stuck in the oil pick up? So basically if it happens again, all i do is drop the pan and see if there is something?

thanks again

 

[Tom F&L GoR]

Last question, from what i can read, there really isn't anything in the system that could have caused a momentary failure of the oil pump or something? Only thing would be if something got stuck in the oil pick up? So basically if it happens again, all i do is drop the pan and see if there is something?

thanks again

Exactly correct.