Oil Burns after prolonged use?

[EloManga]

Well, it's worth a try!
As mentioned earlier in the post, there's a great deal on Formula Shell for $1.67/qt, so I'm gonna use that and see what happens. If the same crap happens, I'll definitely try 0W30 GC. This is conventional oil? Also, wouldn't the XD-3 be similar to this also? They say it is thick like a 40 weight and yet good in the winter.

 

[skate1968]

Hey BITOGers,

After looking at this thread i thought I'd post. I'm noticing that I'm consuming less oil after a fresh oil change. I got a change two weeks ago and i haven't yet had to topp off.

This could be partially due to the fact that it had been overfilled prior. And oil consumption brought the level back down to the full mark.

Could also be that i'm not racing the engine as much. Or that the old oil fill cap that i replaced was leaking. I'll keep monitoring.

 

[skate1968]

Or maybe the recent top end cleaner through the intake manifold helped. I'm not sure.

 

[TallPaul]

I believe it has been stated on this site that dirty oil does not seal as well at the rings, so maybe that is why the consumption goes up after 3000 miles.

 

[Sienna Driver]

quote:

---

Originally posted by EloZE'PGT:
I have a high compression 2.5L V6 Mazda engine and I've noticed that once my oil hits over 3000Km's of use, it starts to burn and/or disappear. I don't believe I have a leak, well not one that requires I add 100-300 ml's of oil per week anyway. Currently I'm using Valvoline Synthetic, 5w30. It has about 5000Km's of use now, but I'm doing highway driving, so I hope to have a longer oci.
Is this common or does it just mean that I need to change my oil? When it's fresh, I don't lose a drop.

---

My understanding is that a small amount of oil passes through the rings to lubricate the piston and then burn off in the chamber, this is normal, and some cars use more oil than others. As miles accumulates so does moisture/fule in the oil, so this kind of evens out the burnt off oil under "normal" dirving condition so that you don't notice oil level goes down. If you do a lot high way driving, the moisture/fule get cook off so notice the level goes down. Another factor is, I think, is that oil diluted by moisture passes thru ring more easily.

 

[skate1968]

Thanks Paul!

 

[skate1968]

TallPaul. I sent a PM to you.

 

[Steelhead]

EloZE,
do you have noticible blowby? pull PCV and observe what comes out the valve cover hole....
high compression engines run higher levels of blow by which has to go somewhere> thru the PCV and into the engine and burned....
the blowby raises the crankcase temps, thus the oil temps and will carry off oil volitiles with it
high compression adds to rod bearing load and thus shearing

the muscle car big iron of the late 60's and early 70's ran high compression, my 429 CJ ran 11:1, and burned oil, quart every 500 miles....normal

manual transmission engines that are ran hard and down shifted for braking will use more oil also....

try using LC to increase oil life

 

[javacontour]

I see the same sort of thing in my Geo Prizm. The first 2k-3k miles, I hardly notice any consumption, then it goes to a quart every 1500 to 2k miles.

This car is driven primarily on urban expressway, with little around town driving most weeks. So I doubt it's an issue of condensation boiling off on a long drive. When driven, the car typically sees 70 to 150+ miles/day.

I suspect part of it is due to being a Toyota 4A-FE engine, with the gear driven DOHC setup shearing down the oil. (One cam is driven by the belt, and the other cam is driven by a gear off the driven cam, clear?)

Shearing, depletion of additive, etc all can contribute to increase oil consumption.

I'm getting ready to AutoRX this car. One bottle should take care of two cycles with a three quart sump capacity

I'll report if there is any change, perhaps some before and after pics as well.

 

[427Z06]

EloZE'PGT, in your case I believe the oil is being worn out early due to excessive blow-by, assuming the PCV is operating correctly. I'd try a AutoRX cycle to see if you can clean up the ring packs.

 

[skate1968]

quote:

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Originally posted by TallPaul:
I believe it has been stated on this site that dirty oil does not seal as well at the rings, so maybe that is why the consumption goes up after 3000 miles.

---

Thanks again Paul.

So if I'm noticing that oil consumption goes up after prolonged use it's likely my engine still has a good amount of sludge in it. Meaning that if i consume more oil after prolonged use then my engine would benefit from cleaning (Arx, more frequent oil changes, etc).

Am i right?

 

[skate1968]

bump

I did a little reading about engines with blow by. As i said before, i was aware of the obvious smoke coming out of my tail pipe at high rpms. But what i didn't realize is that unburned will also go past the piston rings and mix with the oil. So it will make it dirty and it will make it thinner.

In conclusion the older oil in my car will burn quicker because it becomes thinner; it becomes a lower viscosity oil.

[I'm just trying to manage my problem until i get a new engine/rebuild/car.]

 

[skate1968]

I found that this article seems to further explain why oil consumption in my 91 civic is often erratic. I imagine that anyone with lots of blowby would benefit from reading it.


3) The oil becomes fuel diluted with raw gasoline. Gas does not lubricate and an oil filter does not filter-out gas. Gas goes right through undeterred. An oil filter is designed to filter out particulate matter only. Cars that are driven mainly in the city with a lot of low-speed driving, a lot of traffic lights, and do a lot of idling tend to put a lot more unburned gas into the oil. It is common for cars to burn a considerable amount of oil because it has become fuel diluted, reducing its ability to lubricate. Then, because the thinned-out oil cannot seal as well, it will let even more unburned fuel and contaminates past the rings, and more of the oil will burn away. The gas being introduced will sometimes take the 'place' of the oil, and when you look on your dipstick, you see that it is 'full'. This will lead some to believe that their car does not burn oil.

Then, in this example, say you take this car on a 75 mile highway trip and when you get there, you check the oil only to find out that it is 2 or more quarts low! This concerns you, because the car has never burned oil before. So you add a couple of quarts, putting good clean gasoline-free motor oil in its place with nice and new robust additives. You drive home the 75 miles at a little slower speeds because you are concerned about the oil loss. When you get home, you are fully expecting to see a 2 quart loss. But you are surprised to see that it is still on the full mark! So now you are confused. Many will blame the brand of oil, the shop who did the change by installing the 'cheapo' house brand, and some will just scratch their heads in wonderment. Fuel dilution is the culprit. In reality, the fresh oil helped to seal well, lubricate better and prevent excess oil loss.

http://www.boss302.com/oil.htm

 

[ThirdeYe]

I had that happen once when I took a long road trip. I used to only use my car for short trips, only putting on 4-6k a year (5 mile one way every day basically, except in summer it was barely driven at all) and when I got to my destination, I had the oil changed because it was around the 3k mark and they said the dipstick was a half quart low, when before I left for the trip it was at full (with around 2k on the oil). I wonder if it was that same phenomenon.

 

[Craig in Canada]

Same thing can happen with water/condensation. Condensation builds up over day/night cycles and short trips and all burns off on the next long, hard run.

 

[Vilan]

If you have "2 or more quarts" of gas in your crankcase, I don't think your engine will last long enough to need to worry about it.

 

[javacontour]

Quote:

---

I see the same sort of thing in my Geo Prizm. The first 2k-3k miles, I hardly notice any consumption, then it goes to a quart every 1500 to 2k miles.

This car is driven primarily on urban expressway, with little around town driving most weeks. So I doubt it's an issue of condensation boiling off on a long drive. When driven, the car typically sees 70 to 150+ miles/day.

I suspect part of it is due to being a Toyota 4A-FE engine, with the gear driven DOHC setup shearing down the oil. (One cam is driven by the belt, and the other cam is driven by a gear off the driven cam, clear?)

Shearing, depletion of additive, etc all can contribute to increase oil consumption.

I'm getting ready to AutoRX this car. One bottle should take care of two cycles with a three quart sump capacity

I'll report if there is any change, perhaps some before and after pics as well.

---

Well, 8+ months later and things are pretty much the same. I've decided to go conventional oil for 8 months of the year and use synthetic during the winter, for it's benefits as well as not needing to change the oil say from November until sometime in March.

Since this car gets about 2000 to 2500 miles/month, I should be able to go 8K to 10K miles on PP. I may take the approach of topping up with say Pennzoil 10W40 after the first 5K miles on the OCI.

I said I'd report back, so here it is. If the AutoRx slowed consumption, it's hardly noticable.

So my next technique is to stop checking the rev limiter on a daily basis, LOL