Oil Consumption Question

[bugeye01]

I have a 1995 F350 crew cab with 460 and EO40D. This thing goes through lots and lots of oil and I cannot yet figure out where the oil is going. I bought it in Florida with 112,000 miles and drove it home to Kansas City without using any oil. It now has about 120,000 miles. The valve cover gaskets are not leaking. There is a little oil around the pan gasket and on the pan, but not near enough to be the major source of this consumption. There is never any size of an oil puddle under the truck. It never has that odor of oil burning on a manifold or similar. The engine does not smoke. In my experience if it smokes at first start you would suspect valve guides, but it does not smoke at startup. If it smokes when you slam the throttle open you would suspect valve stem seals, but it does not smoke then, either. If it smoke all the time you would suspect rings, but it does not. The last couple oil changes have been at/by local Valvoline shop, and the consumption might have started about the time I started having them do that, but not really sure. I would live for somebody to say they have been through this and know what's going on here. Any ideas?

 

[DNFXDLI]

How much are you going through?

 

[bugeye01]

Well, it holds around 6 or 7 quarts. The lifters started rattling so I took it to Valvoline and they put 3+ quarts back in it. It had only been about 2,000 miles since the oil change. That works out to about a quart in 600 to 700 miles.

 

[DNFXDLI]

That's a lot...have you pulled any plugs to see how they look?

 

[bugeye01]

I have not yet pulled any plugs. Reason: Both exhaust manifold gaskets started leaking, which tricked the O2 sensor into asking for more fuel. I didn't think the plugs would look good anyway under those conditions. I just this past weekend got the gaskets changed and in the process found a hole in the air intake tube. I thought I would give it a week or so of running and then pull out a couple easy-to-get-to plugs. I can't see how the leaking gaskets or the air inleak could cause oil consumption, but.....? Maybe? Otherwise, I will get to that next week. What are you thinking?

 

[Fellro]

If it is trying to overfuel, it can wash the cylinder walls a bit and thin the oil, making it vaporize easier. Another thought, (unfortunately, needs considered) is that when they did the oil change, they only put in 5 quarts, meaning you have actually only lost about 1 quart over that time. I would expect they would upcharge you on the change if it took more than the standard 5.

Even if the plugs were fouled by extra fuel, you would still see oil deposits on the plugs as well.

How does it run in general? Good power and no missing?

 

[bugeye01]

I just typed out a more detailed reply, but the site froze up and lost it!

Thanks. All good thoughts to ponder. It does run good, smooth, plenty of power. Mileage dropped from 12 to 7 when the gasket leak started. So, a new plan emerging:

1. Pull a few plugs to check condition
2. Change the oil myself, make sure it is full and watch it closely
3. Wash off the engine again, thoroughly and watch it closely
4. Make a good check on the gas mileage now that the air & exhaust leaks are corrected.

I suppose I might be able to find someone to do some type of emissions check (Missouri does not do them) that might confirm that all this oil is being burned, or not. Will give that a try, too. Ford has been of no help. Too bad. That is where the expertise should be.

 

[Fellro]

Not sure KC Metro does it or not, I am thinking that St Louis does, had thought KC did, but may be very wrong about that. Many shops don't use sniffers for diagnosis even though it would be a very useful tool.

 

[dustybumpers]

My 94 Centenarian 460 is picky about the brand of oil. Some oils it will go through like water, others it seems to like.
So far the combo it is happy with is Pennzoil 10w 40 and a bottle of stp.

My mechanic said it is the refining process of the brand, and the amount of heat the 460 puts out. IDK
I hope this helps

 

[Fellro]

I have seen that happen on other motors. I at one time ran the Super Tech in the beater daily driver, and would lose a quart or two per change. Started using better quality oil, and the loss stopped. I have seen that with even good oils like Rotella vs Delvac. For some reason the Delvac holds out better in the Cummins and IDI.

 

[5.0Flareside]

My 94 Centenarian 460 is picky about the brand of oil. Some oils it will go through like water, others it seems to like.
So far the combo it is happy with is Pennzoil 10w 40 and a bottle of stp.

My mechanic said it is the refining process of the brand, and the amount of heat the 460 puts out. IDK
I hope this helps

That's part of it.. Its based on NOACK rating.. Higher rating it burns off easier. Pennzoil has a fairly low rating compared to most. You can lose the bottle of STP. No need for it.

 

[5.0Flareside]

There's. Few things need answered.. What viscosity & brand of oil is in question.

Have you done a compression test or leak down test?