I have a 2004 with 5.4. I have had it since around 30,000 miles, and currently have 326,000 miles on it. I have used motorcraft 5-20 and motorcraft filter since day 1. Timing chain tensioners and guides were replaced at 178,000 miles (I even posted a write up about it here with photos). Replaced a leaking oil filter mount gasket around 200,000 miles. Other than plugs, COPs, and throttle body cleaning, I haven't really had to do anything to the engine. I change the oil every 5000 miles, and for the first 270,000 miles or so, I never even had to add oil between changes. It is now starting to burn oil between changes, and I usually have to add 3 quarts between oil changes. I know with 326,000 miles, I should expect some oil consumption, but here is the observation that kinda has me baffled: During the first 2500 miles after an oil change, it uses very little oil, around 1/2 of a quart. the remaining 2 1/2 quarts of consumption comes in the next 2500 miles before the oil change. Anyone know why that might be? No CEL lights, no noticeable loss of power, no noticeable leaks under the truck.

 

I can't explain that phenomenon, but I have noticed the same thing with my cars of old. Perhaps the viscosity of the oil is changing with use? Perhaps when it needs oil, put in a thicker oil, 5w30 or 10w30 or even 10w40?

 

That's common on worn engines, the oil is losing viscosity. You don't want to go too heavy on the oil because of the VCT system, I think 5W30 or even 5W40 (if you can find it) would be safe.

Another option is change the oil at 3k instead of 5k.

 

326,000 miles is the problem.

 

326,000 successful miles is not what I'd call a problem, lol. As reliable as that engine has been, I'd be A-OK with that oil consumption. But yea, the manner in which it uses it seems odd, but as good as that motor has been to you, you almost just wanna say "oh well". If I were adding that much oil, I might even consider stretching out the change interval a little bit.

 

at about 1700+ miles, additives in the oil begins to break down......by 2500 miles, much of the additives are at their minimums.......we use to add zinc to our oils back in the 70's to reduce friction with the racing side of the house.....we did some testing in our street cars to try to establish a reference point of longetivity...and that's what we came up with

 

With 326k, you are going to have some blowby. The blowby depletes the additive package and lowers the viscosity faster than in a tight engine, so it starts burning it. This is why I suggested 3k change intervals, or a heavier oil. If you go heavier, do not get anything that's more than 5W on the lower end, your VCT will hate you.

 

An observation of mine that relates, and confirms @glc and @beachkid's opinion, is a distinct decline in oil pressure relative to miles on the oil change. I have a very nice fancy electronic analogue / digital aftermarket oil pressure gauge on my 2004 5.4L with 221k miles. Hot idle (verified by OBDII reading of EOT) oil pressure with A/C on, in gear, will be 27.5 lbs right after a fresh oil change with 5w30 Full Syn Moblie 1. At 2500 miles, the oil is still pretty and clean - and no more than one quart consumption, but Oil pressure under will be around 25 lbs. By 4000 to 5000 miles, color begins to darken progressively and by 5000 the oil pressure will hover around 23 lbs.


I think the oil becomes diluted with some hydrocarbons and combustion products from blow-by along with a breaking down effect.


PS. Forgot to mention that at 212K, did a complete chain/phaser job and installed a Melling 10340 Oil Pump (definitely boosting oil pressure).

 

Thanks for the info. I was sure that I was getting blowby at 326K miles, but I wasn't quite sure why the curve in oil consumption. I've used the 5-20 exclusively because of the vct system. If I do switch to 5-30 will that not mess up the VCT? Will it really help reduce blow by that much? Originally, I had just planned to keep going every 5000 miles with 5-20. I mean, it's worked pretty good so far.

 

My suggestion was to add a thicker viscosity oil when it needs a quart to bring the overall viscosity back up, not from the beginning. Free advice is sometimes worth what you pay for it! Ha! By the way, congratulations for getting that many miles out of it!

 

Yes, I've been ridiculously happy with the reliability of this engine. What's even more impressive is that all the parts that you would expect to have needed replacement have not needed it. Starter, water pump, alternator, A/C compressor, Power steering pump...all original. I might try adding the thicker oil between changes. What about an oil additive like STP or Restore to help slow the breakdown of the oil? I've never used additives before with this truck. I had come to the conclusion that they were not worth the money, but then again, I've never had an engine with this many miles before either.

 

Those additives (STP, Restore) thicken the oil, which you do not want for cold starts. This is why I said to stick with a 5W something.

 

Yeah, the cause is the blowby in the engine makes for more internal heat. The oil is pretty much been hammered by heat by the time it gets to 2500 miles. Blowby is getting around the worn rings. The fix is twofold, use a heavier viscosity oil and use an oil with the lowest NOACK. Right now, that would be Pennzoil yellow bottle 10w-30 and the best part, it's usually cheap. It beats most synthetics at not cooking off. I would strongly suggest with the miles you have on it, to move to a heavier viscosity oil like a 30 or even a 40. The issue is the bottom bearings are worn and the oil is currently leaking out of them that should be sprayed on the rings, hence the blowby you're getting. Your rings are running in an oil starvation environment. You can add miles to the engine by moving up. The 10w part, since yer in Texas, is good enough unless you live where you have cold startup at minus 25C which I doubt in Texas. Might even consider moving to dual rated oil like Delo 400 in 15w-40. It has the best formulation as of now and will stay on the job. Per oscilloscope readings, the heavier oils do not effect the valve timing at all. Ford even recommended 15w-40 oils on the 5.4 where the valve train was making a lot of noise. It might effect the gas mileage by 2%.

 

You have no idea what you are talking about. 2500 miles the additives are at their minimums???????? In case you haven't noticed this isn't the 50's, 60's, or 1970s.