Car using oil on long trips?

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My 98 Towncar seeks to be using oil on long trips.

I changed to Castrol Edge 5W30 with MC FL-820s and immediately took the car on a long (16 hr) trip. Had to add more than half a quart half way through the trip and another 1/2 qt after the trip was done. Then, after getting back and driving my normal amount and finishing out the OCI, it never used another drop.

I changed it again, using the same Edge and 820s as I used before, drove around about 500 miles of normal commuting without using any oil. Then took it on a 1000 mile trip somewhere and it used 3/4 qt on the way there. Drive it another 1000 back and it used a whole quart. After getting back, I put another 1000+ miles on the car doing normal driving and commuting and it didn't use any at all.

My daily commute is about 20 miles each way, taking 20 mins to get to work in the morning and about 45 mins (with traffic) on the way home. The Lincoln does not seem to use any oil in my normal commute, but if I take it on an extended road trip (6-8+ hours), it uses at least 1/2 to 1+ quart of oil. A shorter (roughly 3 hrs) road trip it will not use oil. There are no leaks under the car. Engine runs great, no smoke or oily burning smell from exhaust.

I just changed the oil again, this time using Mobil1 to see if it makes a difference. I know these 4.6 engines are known to have the valve stem seals wear when they get up there in mileage, but wouldn't it use oil all the time if that was the case? This thing only uses any on really long drives and never any on local or shorter trip driving. What do you all think would be causing this?
 
So the long trip situation was high manifold vacuum at cruise. Around town and commuting is variable vacuum as you accelerate, etc. Different operating parameters.

Go through the PCV system and make sure it's all clean tight and working as it's supposed to.

Many of those Ford system have the PCV valve laying sideways and they gunk on one side. They'll pull oil any time they see high vacuum ...
 
On short trips you accumulate water and fuel in the oil, which you boil off on a long trip, making it appear there was sudden oil use. At least that's what people used to say. I'm not so sure there would be that much water and fuel in the oil however (1 quart in 5, or 20% seems unbelievable).

That doesn't explain why it would use a second quart on the trip extension.

But it could explain some of the apparent stopping of oil use when you get back.

Back in the day I had a Ford that burned oil. It seems it would be pretty good right after a change and then after a while it would start to use oil. At the time I assumed there was a gradual loss of viscosity and at some point the oil would be thin enough to get past the rings. But that was pure speculation.

And anyway I think oils maintain their viscosity better nowadays.
 
I would check the PCV system as already mentioned. It could also be that the longer trips are getting the oil to full operating temperature and it is staying there for a long time. The hot oil at operational viscosity might be getting past parts like worn valve guides and/or worn rings, both of which can have signs of wear. The vehicle in question is from 1998 and has 126K miles on it. That could be a possibility. If the PCV system checks out you might want to try something like Mobil 1 0W40. Or it could be as simple as bad valve stem seals.
 
If you aren't seeing smoke on engine start or hard acceleration from a red light, then valve seals are most likely not the problem. PCV change would be my first thought to change. My 96 Merc GM had 218K on it when sold and used a qt every 6500 Miles from new to when sold. Try M1 10-30 HM for several oil changes.
 
Originally Posted By: ecotourist
On short trips you accumulate water and fuel in the oil, which you boil off on a long trip, making it appear there was sudden oil use. At least that's what people used to say. I'm not so sure there would be that much water and fuel in the oil however (1 quart in 5, or 20% seems unbelievable).


yeah but it started out with brand new oil. I like the PCV idea.
 
The PCV valve is almost always the one thing to blame with weird oil consumption patterns on the 4.6 Ford V8.
 
Has the car been on conventional its whole life? If so, I'd expect some consumption with a fresh synthetic oil at 125K miles.

Try some Maxlife syn blend 5W30 next time.
 
No, the engine on this car barely turns over on the highway, the RPMs are probably like <2000 at 80mph. When I'm driving around town, I accelerate much harder and RPMs come up much higher than they do when I take it on long, easy freeway cruises.
 
Originally Posted By: eljefino
Originally Posted By: ecotourist
On short trips you accumulate water and fuel in the oil, which you boil off on a long trip, making it appear there was sudden oil use. At least that's what people used to say. I'm not so sure there would be that much water and fuel in the oil however (1 quart in 5, or 20% seems unbelievable).


yeah but it started out with brand new oil. I like the PCV idea.

I do too. I'd investigate the PCV.
 
I acquired the car with 105k on it and started using full synthetic around the 110k mark. Never seemed to use any oil before and I was using either Mobil1 or Valvoline synthetic but the last 2 oil changes prior to this most recent one with M1 I used Castrol synthetic and it seemed to use some when I ran it, but only on really long trips. Haven't had this most recent fill of M1 in long enough to tell if it's using any more oil yet.

Based on what service records I have, the previous owner ran either 5W20 or 5W30 conventional or stnthetic blend. I've always done 5W-30 since I've had it and full syn for the past 11,000+ miles.

Another detail I may add is I am driving this car a LOT more than I was when I got it, too. I was only putting on about 1500-2000 miles a year when I first acquired the car about 4 years ago. This past 10 months, I've done about 8,000 miles so far and in the next 2 months I am on track for another 2000 or so.
 
I'll go buy a new PCV valve and change it out to see if that helps. It is really sounding like that is the case with my car, especially with how many people in this thread have suggested it.

I really don't think (and am hoping it is not) the rings or valve seals, and the lack of oil burning smell and exhaust smoke and the fact that it doesn't use oil all the time, only on long drives, leads me to believe that is not the case.
 
A couple of you suggested trying a high mileage oil, I know HM oils have seal swellers in them to help slow or stop leaks (which my car does not seem to have any leaks currently). They say not to go back to regular oil once you have started using high mileage.

What are the advantages and disadvantages of HM oils? Do they have stronger add packs for protection/cleaning/reduced wear than regular syn/conventional oils?

I don't know about trying a 10W oil yet. My owners manual says 5W30 but Ford back specced the car for 5W20. I wouldn't really want thicker than a 5W. I was thinking about giving a 5W40 oil a try. Some people say these 4.6s like Rotella 5W40 oil and M1 0W40 is great in these engines, too. All I have used so far since I've had it is just 5W30 though.
 
There was a TSB for the Expedition and F-150 for high consumption that involved new PCV plumbing. That would be the first place I'd look as well.
 
Originally Posted By: Jack2468
A couple of you suggested trying a high mileage oil, I know HM oils have seal swellers in them to help slow or stop leaks (which my car does not seem to have any leaks currently). They say not to go back to regular oil once you have started using high mileage.

What are the advantages and disadvantages of HM oils? Do they have stronger add packs for protection/cleaning/reduced wear than regular syn/conventional oils?

I don't know about trying a 10W oil yet. My owners manual says 5W30 but Ford back specced the car for 5W20. I wouldn't really want thicker than a 5W. I was thinking about giving a 5W40 oil a try. Some people say these 4.6s like Rotella 5W40 oil and M1 0W40 is great in these engines, too. All I have used so far since I've had it is just 5W30 though.


M1 HM is on the thick end of the 30 grade, is A3/B3 certified and available at Wally World.
Thicker is slower to slip past seals

You can go back and forth between HM and non-hm oils. It won't hurt anything. All engine oils have seal conditioners.
HM oils may have more detergents and dispersants to aid cleaning.

Replace the PCV valve with an OEM part
 
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