So today I was driving around doing some errands and it was unusually warm so I was going to seafoam my truck because I noticed that my mpgs dropped nearly in half. I wasnt sure if it was just because it had been really cold or what was going on. But anyway I checked the oil level before doing anything and my dipstick was dry . Then I opened up the oil cap and all I could see was white sludge. I proceeded to freak out because I do not have any oil leaks, let alone a leak that would drain my oil pan. Thankfully some old guy in the parking lot came up to and told me the white gunk was just from water getting into my oil (once again not sure how that is happening). I cleaned out all the gunk the best I could, got some mobil 1 full synthetic and a new filter and changed the oil. Turns out I still had a little oil in the pan, actually a little under 4 quarts, so I dont think I did do much damage. But still more than 2 quarts of oil missing is enough to stress me out. Now that I changed the oil she is running great, I cant believe I didnt notice the drop in performance. I am pretty sure I was just blaming it on the cold.

Is it possible that my engine is burning oil? or is it probably a leak that I am missing? How big would a leak have to be to leak out over 2 quarts in a few months?

It is the 5.4 and has 167,700 miles on it. If this is the case why did the oil level gauge in my truck not let me know? It still read that the oil level was fine. What does this mean for my truck if it is burning oil?

Any help with this would be great because I definitely want to get to the bottom of this.

 

The gauge on your dash doesn't read oil level, it reads oil pressure. You probably still had good oil pressure most of the time, except for maybe sharp corners or heavy braking/accelerating. If you had run it for any length of time without oil pressure you would have known, and you probably wouldn't still be driving it.

As for the white gunk, its just condensation build up on the cap, turning the oil white and sludgy, its perfectly normal. And as for the low oil condition it could just be burning oil, at 167,700 I wouldn't be surprised.

I'd thoroughly check for any leaks though, just to be sure.

Good luck!

 

Thanks, Good to know. I really couldnt believe how much white gunk there was. Literally large blobs of it, the guy at autozone was shocked.

I figured oil pressure and oil level went hand in hand, but now that I think about it, that doesnt really make much sense. So what does it mean then if my oil pressure drops for a good amount of time? Because a few weeks ago I drove it 4.5 hrs and halfway through the trip I noticed the oil pressure was really low. But when I came back the next day it was fine? Does this indicate leak somewhere?

 

Also what usually causes an engine to burn oil? Sorry I am complete newb when it comes to engines.

 

No problem, everyone starts somewhere. I myself am new to these modular motors, before this truck my oldest vehicle was a 1990 and my last F-150 was a '78.

A motor will begin to burn oil just from simple wear, valve seals get dry and cracked and let oil seep by, piston walls get scorched and worn down, along with piston rings cracking and wearing as well.

When your oil pressure dropped, how low? Was it still in the normal band?


My buddy had the same problem in his '91 5.0 stang. We were on a 4.5 hour drive as well, and about 1/3 of the way through the pressure got pretty low on the gauge as well, (still in normal range). We were pretty paranoid about it, and pulled over and checked the oil level and all was good. We let it sit for a while when we got some food and when we left again it was fine all the way back. Although his is and was burning oil something terrible due to valve seal issues.

 

With high mileage, the metal on metal between the pistons/rings and the cylinder walls has probably created a passage for oil to get from the crankcase to the combustion chamber. Worn piston rings and/or worn cylinder walls cause this. Not sure how these newer engines are, but bad valve stem/guide seals can also cause oil to to be sucked into the combustion chamber from the valve train. This is most noticeable on startup. If oil is getting past the rings, compression will be lowered in those cylinders affected. Valve seals don't affect compression as much if at all. As you know, if there is oil in the combustion chamber when the spark plug fires, it will be combusted along with the gasoline and this causes the blue oil smoke out of the exhaust pipe. Don't worry about it at this point in time. Just keep the oil checked and changed and it will go many more miles.

 

That situation sounds exactly like what happened to me, except it hasnt done it again. How did your buddy know what was wrong with the engine? Like what would indicate more serious problems than just burning a little oil? How much oil did you friends stang burn?

 

Concerning the white sludge, in the colder weather U get more moisture build up in the engine, just because of the huge temp difference between the hot engine and the cold atmosphere, as the engine cools and the air in the engine condenses it pulls more air into the crankcase, and because it takes longer for the engine to reach full temp it probably isn't evaporating all the moisture out of the engine. Not much U can do about it except change U'r oil, or go for a long drive every once in a while. Letting the engine idle won't help, it won't get hot enough.

 

Well, it currently burns alot of oil, a quart a tank. We know its the valve seals because a few months ago we tried changing the valve seals because the old ones were, old. However somebody rebuilt the engine at one point and when we put in new factory seals they didn't really fit tight, and now it burns more oil than ever. We're hoping to get the right seals on it this winter.

If you had more serious problems than burning a little oil, you might here a knock or a tick, or maybe even a screeching noise. If you had a serious problem it would probably be fairly obvious.

 

I guess im lucky. I run 5w-30 weight Valvoline conventional and have 178k on my 97 4.6L I go through about a half to almost a quart in 3k miles. I know im near the end with the miles but she still runs like a champ.