weird looking oil, less than 1000 miles

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Sep 12, 2002
Car: 1981 Ford T-bird
Oil: Super-Tech Synthetic 10W-30
Filter : Wix/Penske for the 1991 Ford Crown Vic Police w/ 5.8L V8 (smaller height)

Problem: in less than 1000 miles, the oil filter appeared to be totally clogged and the oil that came out was pitch black and had the flow rate of mud. One of the fuel evap hoses from the carburetor HAD come loose and it was running rich for a few weeks. I'm not sure if this might have a lot to do with it.

The oil filter came out and I tried to drain it - nothing came out. I let it set down on the floor (inverted so that the oil would drain to the bottom) but nothing drained out like it owuld normally drain.

My 2000 Crown Vic had used SuperTech Synthetic 5W-30 for quite some time and the oil is still clear so I doubt its the oil quality that's the culprit.

The 302 V8 in my T-bird HAD used 10W-40 throughout its life, and about 4 years ago I scooped out a bunch of sludge on the valley deck during my intake manifold R&R. The oil is always changed in 3 months/1000 miles with a new filter for the past 22+ years.

This current oil has less than a month/under 1000 miles on it.

Any ideas?
It is quite possible the oil gelled on you when it was cold,,seen this before in a new unopened container of dino oil . Save some, have it anaylized then if warranted take action

I have inspection coming up in about 2 months, so I decided to just mix 4 quarts of Pennzoil PureBase 10W-30 (GF-3) with 1 quart of Super-Tech Synthetic 10W-30 (20% synthetic blend basically) until inspection is over.

I'm going to keep an eye on the air/fuel system to make sure its working OK - and just use 5 qt of synthetic afterwards.

But it sounds definitely like gelling?
I can't believe you are still going to drive it with this problem. If you don't need to drive it, I would have it analyzed to see if there's any antifreeze or other clues in it.
This is the first time its happened.

The evap fuel hose fell off so I'm not sure what it is right now.

Anti-freeze mixing with engine oil shouldn't turn it BLACK. It should be milky, its anything but milky.

But yeah - I need to drive it. There's no other choice, I'm all out of backup vehicles.

[ January 04, 2003, 03:58 PM: Message edited by: metroplex ]
This sounds like a job for a mechanic to diagnose. Anyone out there have any clues? Could this happen from getting fuel in the oil? Sounds like this would be more caused by heat so where could it be getting so hot to be sludged so quick?

Definitely once you get it figured out, time for several Auto-Rx treatments!
I wouldn't be surprised if it was just dirt/gunk that was washed out of the engine... the oil filter appears to be completely clogged!
with your change schedule, 3 months or 1000 miles, I'm shocked that it would be sludged. If that's all it is then why not give it a good cleaning with some Auto-Rx or Neutra treatments?
You are in NJ so temperature extremes shouldn't come into play. An evaporative line off, I would think, would lean it out since you now have a vacuum leak. Have you checked the cooling system to make sure it is full? Any signs of overheating? Injection system was relatively unsophisticated in 91 so the O2 sensor would do it's best to keep the AFR within spec in closed loop. I would keep looking, but I don't see why it would be either the oil or the filter itself. They are likely the symptom, not the problem.
Actually its a 1981 T-bird, so its got a 2-bbl carb no O2 sensors.
The evap hose comes off of the top of the fuel bowl into a charcoal canister.

The coolant looks ok for now, but would coolant mixing w/ engine oil cause it to turn pitch black like this?
I agree with vettenuts, it's not the oil or filter that's the problem, but they are the symptom of A problem.

My understanding is coolant will thin out the oil, causing loss of lubrication. Does your coolant level stay constant?

I think the color of black occurs from carbon burning which is either the oil or gas burning. The thick oil is caused by overheating the oil in my opinion but what's causing the heat I don't know. Have you done a compression check?

1. Is the thermostat opening?

2. What do the plugs look like? Are you getting sufficient power to the ignition system?
I have a 160F T-stat and for the past 1+ years its been working fine.

The spark plugs look great, no fouling or anything - I'm using the stock heat range plugs.

Prior to using the synthetic, I had been using dino 5W-30, 10W-30, and before then I was always using 10W-40. I've never gotten the oil to be this black before and i've never clogged the oil filter before. The oil poured out pretty thick and "muddy". No solid particles floating around tho.

In contrast, my 2000 Vic once had the Super-Tech synth 5W-30 in the engine for 3+ months (same mileage as the T-bird) and the oil was still clear/yellow on the dipstick. The dipstick on the T-bird showed the oil was definitely blackish.
The 160F t-stat worked fine last winter. My oil didn't turn black in the winter. I have no problems with getting heat in the winter - it comes on normally. I just notice that I get much less pinging. Normally I'd ping even when using 93 octane, stock plugs, stock timing - ever since the car was bought brand new.

With a 160, I can run advanced timing with 87 w/o pinging. A design flaw in the cooling system I guess (low perf water pump, puny radiator, etc)

I use a 180F t-stat for my Vic becuase of the chip.

I'm positive the black oil condition is becuase of the low temp t-stat. The car warms up fine in the winter, and I've had the 160 in there for 1-2 years now, and its been thru the winter before. This is the first time in 22+ years that oil came out like this. I'm pretty sure the fuel evap hose that came loose from the fuel bowl had something to do with it. What I don't understand is why the oil would thicken out and clog the oil filter.

[ January 05, 2003, 01:32 PM: Message edited by: metroplex ]

I once used a 160 F thermo in the '86 Burb for about 6 months during the winter. Oil sludged up terribly. Now the Holley Spreadbore carb runs rich anyway, so this I am sure it contributed to the extra carbon as well.

Too hot a temp will cook the oil and oxidize it and too low a temp will not allow the oil to evaporate and cook-off the fuel. The hot blowby gasses will tend to partially burn the fuel in the oil and carbon up the oil. Partially burned fuel is a carbon maker for a cool running engine.

I agree with patman, a 190-195 F thermo would be the better solution.
but again its not like I just installed the 160. I had it for 1-2 years, not once did the oil sludge up like this in the winter and I used to do 3 month changes - the oil would come out like oil.
In fact, I did the oil change on 11/28 - I checked the oil around the end of December - it looked very clean.

When my dad went to adjust the idle mixture screws he must have dislodged the fuel bowl hose or something. After that one day I couldn't get it started - I found that the engine was somehow flooded. I'm wondering if that can cause it to sludge so quickly... because up till last week the oil was looking good on the dipstick. The morning I went to check on the flood condition, the dipstick oil was pretty black.

The 160F t-stat seems to work very well with the 302 V8. I wouldn't go below a 180 for EFI vehicles tho.

[ January 05, 2003, 04:06 PM: Message edited by: metroplex ]

Originally posted by metroplex:

I have inspection coming up in about 2 months, so I decided to just mix 4 quarts of Pennzoil PureBase 10W-30 (GF-3) with 1 quart of Super-Tech Synthetic 10W-30 (20% synthetic blend basically) until inspection is over.

I'm going to keep an eye on the air/fuel system to make sure its working OK - and just use 5 qt of synthetic afterwards.

But it sounds definitely like gelling?

Well initially it did look to be suspect of gelling,now so much more info has surfaced that was not upfront in the first post who knows? I would say stick the correct t-stat in it and change the oil and see what that does for the situation,,if you have any of the original oil left in a bottle,stick it outside and see if it gells,easy to see,looks like jello not quite set
When I went to transfer the old oil into collection jugs, the oil had settled for at least 5 hours. It was very black and mixed (solution) and not a gellatinous mixture.

Changing the t-stat is a PITA for this vehicle, so I'll just leave the 160 in there (hasn't given me any problems for the past 1-2 years) and see what happens. I suspect its excess fuel that caused the blackening - but I wanted to hear some 2nd opinions on what fuel can do to the oil.

Why would you be running a 160 thermostat in the winter? It's not a good idea to run a colder thermostat once the temperature drops below 40F. As a matter of fact you don't even need to be running a colder thermostat except for in the hottest of weather. You'll just run colder oil temps so your oil will not stay in good condition as long. I've seen data on the net which suggest you're shortening your engine life with the use of a colder thermostat in colder weather too.
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