Burning oil only on the highway

[100branson]

Hello, everyone

New to this forum although I've been looking through it about everyday.

I just bought a 1989 f350 4x4 it sat for couple months before I got it but the owner before me swears it didn't burn oil but, words are cheap. Well 3 hours drive home after buying it I was low on oil. Changed the oil and filter drove to Amarillo going 70mph 320 miles I lost 3 quart's
Cleared the CDR. Drove it home 70mpm burned 3 quarts. Order a new CDR I drove back to work in Amarillo at 75mpg lost a gallon of oil. But in town I have no issues 150 miles around town and oils still at the full line when it's hot. It does idle rough Some of the other posts I have seen said that auto rx helped alot going to order that now. Other checking compression what else could or might cause this? Can the CDR be overwhelmed with to much blowby and put oil into the intake?

 

[franklin2]

Some guys try different brands of oils. Some seem to be burned quicker than others. I have noticed that myself. Some also report the first quart goes fast, but then it settles down and it's a long time before it burns the other quart to the add mark. I have noticed that on mine also.

Are you putting 10 quarts in? The low mark is for 2 quarts low on my truck, which is a 89 also.

 

[Thewespaul]

Is the truck smoking at idle? These trucks will eat rotella like candy. Any oil leaks or is it truly burning the oil? How does the coolant look? Kinda milky?

 

[100branson]

Yeah, I've put 10 quarts ( 2.5 gallon jug delvac 15-40)
And didn't fill it back up with oil until it was at or below to fill line.

 

[100branson]

Is the truck smoking at idle? These trucks will eat rotella like candy. Any oil leaks or is it truly burning the oil? How does the coolant look? Kinda milky?

Oil was pitch black only on start up does it smokes for a few minutes. starts fine when it was 30degrees out figure compression can't be that low
Oil leaks on the valve covers tightened it up and they haven't leaked much since

 

[Shadetreemechanic]

How much blow by does it have? Loosen the oil cap at idle. Does it sit there or does it blow off from the back pressure? My experience is that worn engines burn more oil on highway than around town.

 

[chris142]

Is the thermostat allowing it to get up to 200f or so? Mine burns oil too. Valvoline 15w40 lasts the longest in mine.

 

[Thewespaul]

FYI my truck has over 250k miles on it and runs great starts cold with hardly a turn of the crank but it burns a gallon of oil a week (over a thousand miles I drive a week) I will be removing this engine and replacing it this winter.

 

[100branson]

With the new CDR on there's no back pressure now when you pull the cdr off and test it from the back of the engine theres alot. I'm not sure it's getting to temp the gauge says no but the radiator and heater sure feel like it's getting up to 200 I'll checking it without a temp gun

 

[Macrobb]

The cdr shouldn't have any affect on it, because it's wice open 99.9% of the time.

Check your air filter; make sure it's clean.

Use non-rotella 15w40 oil. If it still burns a lot, you might well be looking at a re-ring job.

 

[Hydro-idi]

Seeing the rate of oil that is being used, if it’s not leaking it, it’s burning oil and it sounds like that engine is about due for an overhaul.

 

[Runningaford]

I just switched from Rotella last oil change; while running Rotella, I was constantly adding. I've switched to Mobil, and also kept an eye on it at the 'low hash mark'; so far, it hasn't used any below that hash mark; I think I'm about 2,000 miles into the Mobil.

Perhaps, the Rotella would've stayed at the lower mark as well, not sure.

 

[100branson]

The cdr shouldn't have any affect on it, because it's wice open 99.9% of the time.

Check your air filter; make sure it's clean.

Use non-rotella 15w40 oil. If it still burns a lot, you might well be looking at a re-ring job.

Added some of that auto rx to the oil along with 3 quarts of Valvoline and a new air filter now I see blowby when I take the oil cap off or the dipstick.
Can a dirty air filter make you burn oil?

 

[Thewespaul]

The air filter was more restriction so the cdr saw more vacuum, hence why you are now seeing blowby. An air filter won’t make you burn oil

 

[100branson]

I contacted the old owner about it given he said it didn't burn and apparently he used a gallon of Lucas in the oil so yeah probably another motor in the future will post if anything changes