My 03 7.3 with 170K uses about a quart every 3K miles.

Our 94.5 7.3 with 450K+ uses about 1-2 quarts per 3K miles.

Could possibly be turbo seals, is your tail pipe dry or "a little damp or wet"?

 

I was told by a diesel shop that they would only recommend using a 15w because 5w was too thin for the 7.3. Now I take that with a grain of salt but I am switching to scaeffers supreme 7000 15w-40 sin. blend this weekend. It offers the same characteristics as a thinner 5w at start up according to Schaeffer's. I like running as close to the manufacturers spec as I can though.

 

Well the tail pipe is dry. I am going to pull the intake duct off and see if I see signs of dampness anywhere.

 

I've heard the same thing, may switch to that the next oil change. I think I am out of 9000 so will probably just buy 7000.

 

can you buy in store close to you? I'm ordering online...haha kind of a bummer but hopefully its worthwhile

 

If you are talking about Schaeffer's, yes my buddy is a dealer.

 

nice! good to have some friends haha

 

Well it's weak, but it's the best I can do for now. Maybe it will show up ok

I used rotella 5w-40 synthetic and rotella 15w-40 blue and red lines respectively. On this graph they appear to have fairly equivalent viscosities around 40*C (104*F) in my opinion. It doesn't take long for EOT to hit 104*.

 

my 7.3 used one quart for 5000 miles last oil change over 200k on the clock with Schaeffers 5w40 9000

 

Thanks for this Jeff, always good to see some charts.

 

So I have been talking with a Ford Engineer. Open to what all of your thoughts are. This is the conversation below:

Me: Is it normal for a 7.3 PSD to use about 1 quart of engine oil per 1000 miles?

Engineer: Vehicles in normal service should get at least 1,450 km per liter (900 miles per quart) after 16,000 km (10,000 miles) of service. High speed driving, towing, high ambient temperature and other factors may result in greater oil use.
I would also get the 5w-40 out of the vehicle, and go back to our recommended 10w-30 Diesel Oil. Make sure it’s a “CJ” rated Diesel Oil!!!!!!!!!!! This should be all you ever needs unless you are working the pipelines of Alaska!! You also have to make sure the oil has Anti-Foam properties for Diesel Engines. The Motorcraft Diesel Oil already has this. If you want to use a Shell Rotilla-T, (which is fine) then you need to add a bottle of the Motorcraft Anti-Foam additives. This is hugely important!!!
Also, make sure his air filter is clean!!!! If not, then it starts sucking oil out of the crankcase and into the turbo/engine to burn it!

Me: With your oil consumption guideline are you saying that 1 quart per 1000 miles is acceptable then? My driving primarily consists of 8 miles to work and 8 miles back which I know is not really good on a diesel since it doesn’t allow everything to fully warm up.
The Schaeffer’s 9000 is CJ rated. There are a lot of 7.3 owners out there running the 9000, even in Florida and Texas. I have attached the certification sheets for the 9000.
I am running a clean aftermarket air filter. My crankcase is not plumbed into the intake any more. It now basically just dumps out under the truck into the atmosphere.

Engineer: Per the guidelines, your vehicle is not excessively using oil.
I have head of people using all type of products and fluids in their vehicles, but it doesn’t’ mean it’s the best thing for their vehicle. (I’ve seen many horror stories).
If it was my own vehicle, I would only use the oil that the engine was engineered to use. I would also make sure I changed the oil per the manufactures recommended guidelines, regardless of what oil I am using. The 7.3L relies on the oil to fire the injectors, and it reaches very high temps & pressures, so it’s very critical. I’ve dealt with many people with 600,000+ miles on their 7.3L that stuck to the recommended oil & maintenance procedures since they bought the vehicle. On the other hand, I’ve dealt many people that try various after-market gimmicks and alleged improvement products that don’t work as well. Remember Ford & International spent a lot of money & time designing that engine to provide as much torque, horse-power, & fuel-economy as possible, while at the same time being as durable & reliable as possible in order to be the best truck available. So if there was a product available that would help us achieve those goals, don’t you think we would have used it!
It’s good that you’re running the anti-gel additive, but you may also benefit from using the “Anti-Foam” Oil Additive.
I hope your truck provides many more years of service, the 7.3L is a fantastic motor!!!!!

So after all of this it makes it sound like everyone should be running 10w-30 with an anti-foam additive. I do not believe all of this. Does anyone know if Schaeffer's has an anti-foam additive in it?

 

Wow, interesting information. I am running a fully synthetic 15w-40 oil and have had no consumption issues. I don't add anything to my oil and take occasional oil for analysis and the oil has never been an issue. Even with extended drain intervals. My truck sounds smooth and relatively quiet for a 7.3 liter motor that is 13 or so years old. I do think that you will eventually find an oil that your motor likes and you will hopefully discontinue an oil consumption issue, however it is being consumed.

 

Ya I have had an oil analysis done at 10k mile interval too and everything checked out good. Probably will do it again at the next oil change. I'd definitely like to find the leak.

 

10w30?? I thought 15w40 was the recommended oil???

This 'engineer' sounds like he has a bit of fact mixed in with some BS - but I'm just a dum redneck, so I dunno for sure....

That anti-foaming is SPOT-ON. I have run AE on trucks with poor ICP and 1211 codes and found out the saavy owner preferred walmart-brand oil cause its a little cheaper. After putting Delo or Rotella back in it the problems went away.

 

Agreed, he's got stock in motorcraft or something. Rotella and delo both have anti foaming properties.