Oil burning, where is it going?

truckguy82 · April 5, 2021

Motor L86

oil loss = about 1 quart every 2k miles

-happened since I bought the truck with 20k miles, now has 60k miles

-street tuned by justin at blackbear. When looking at the live data he said it definitely doesn’t look like its the rings. Not sure how he could tell that.

-i also don’t think its the rings...because if I take it easy on my truck for a few days, and then I go WOT, I get a ton of black smoke out of the tailpipe. But this doesn’t happen if I go WOT frequently. Which means in my theory is, the oil is collecting somewhere and then is getting sucked into the engine at WOT. Once I deplete the pool of oil, it stops smoking. Typically when vehicles have bad rings, it will happen every time you go WOT.

where the F is it going? It must be fixable without a rebuild if it’s not the rings and some peoples trucks don’t burn any oil.

Edited April 5, 2021 by truckguy82

pokismoki · April 5, 2021

i think these new engines have weak oil control rings installed on the pistons wile using very thin 0-20 oil, it might help if you use 5w-30 or 10-30w this summer, see if that helps

try installing a cheapo catch can off amazon inline with the pcv system

Edited April 5, 2021 by pokismoki

Z45 · April 5, 2021

fyi..............

Quote

Oil Consumption
The accepted rate of oil consumption for engines used in the vehicles referenced is 0.946 liter (1 qt) in 3200 km (2000 mi).

Important: This rate only applies to personal use vehicles, under warranty, that are driven in a non-aggressive manner and maintained in accordance with the appropriate maintenance schedule, with less than 58,000 km (36,000 mi), or driven at legal speeds in an unloaded (for trucks) condition.

Important: This rate does not apply to vehicles that are driven in an aggressive manner, at high RPM, high speeds, or in a loaded condition (for trucks). Oil consumption for vehicles driven under these conditions will be more.

Many factors can affect a customer's concern with oil consumption. Driving habits and vehicle maintenance vary from owner to owner. Thoroughly evaluate each case before deciding whether the vehicle in question has abnormal engine oil consumption.

Edited April 5, 2021 by elcamino

JONBLARC7 · April 5, 2021

Thats about how much my cammed L86 drinks in the summer. I did the same thing before I had the cam too.

Grumpy Bear · April 5, 2021

0.03% to 0.05% of the fuel burnt is the normal and useful range, new to needs a hard look. As fuel it tied to load and tune.....

This is far less than the GM 'canned' reply for warranty work. This isn't 'normal' by any school of engineering. It IS the point at which GM is willing to do something about it. "Normal" is the word they use to make you feel better about a truly awful lie they are telling.

There is one form of leak you will never see on the ground. Intake manifold runner gaskets. Just tossing that out there. Rings one would check with a 'leak down' test. Not live data :wtf:

When is the last time the PCV valve was checked? Failed open will build a puddle. Plugged baffles in the drivers side valve co cover. Something is 'pressure balance" amiss.

truckguy82 · April 6, 2021

22 hours ago, pokismoki said:

i think these new engines have weak oil control rings installed on the pistons wile using very thin 0-20 oil, it might help if you use 5w-30 or 10-30w this summer, see if that helps

try installing a cheapo catch can off amazon inline with the pcv system

Tried 5-30 no difference

truckguy82 · April 6, 2021

18 hours ago, Grumpy Bear said:

0.03% to 0.05% of the fuel burnt is the normal and useful range, new to needs a hard look. As fuel it tied to load and tune.....

This is far less than the GM 'canned' reply for warranty work. This isn't 'normal' by any school of engineering. It IS the point at which GM is willing to do something about it. "Normal" is the word they use to make you feel better about a truly awful lie they are telling.

There is one form of leak you will never see on the ground. Intake manifold runner gaskets. Just tossing that out there. Rings one would check with a 'leak down' test. Not live data

When is the last time the PCV valve was checked? Failed open will build a puddle. Plugged baffles in the drivers side valve co cover. Something is 'pressure balance" amiss.

I’m going down the rabbit whole of the pcv system.

the thing is, i’ve looked into my intake several times since I use valve cleaner before each oil change. I’ve never noticed any oil in the folds of the intake hose, on the butterfly valve, or inside my limited view of the intake mani.

But it has to be pooling somewhere. You should see the smoke at WOT if I’ve been babying the truck for awhile. Just a huge cloud of black behind me like I have a diesel. Then it goes away completely. If I drive like an ass for multiple days, there will be no smoke.

i’m pretty sure that eliminates any sort of internal engine issues.

One thing I found, on the 2017 c7 vettes, is that they reduced the diameter of the breather tubes. (There’s probably a lot more to it than just thinner tubes) Then I found a random post from a seemingly educated man how to breather tubes for our motors are too big. Hmmm

truckguy82 · April 6, 2021

Also I found out the v6 uses a totally different pcv and afm manifold. Wonder if the v6’s are pretty much all oil consumption free.

mookdoc6 · April 6, 2021

4 minutes ago, truckguy82 said:

Also I found out the v6 uses a totally different pcv and afm manifold. Wonder if the v6’s are pretty much all oil consumption free.

Hardly? GM revised yet again on the LGX 60 High feature for the previous couple iterations and oil consumption.....Your oil will continue to disappear with your dirty rings that simple.

lucas287 · April 6, 2021

23 hours ago, truckguy82 said:

.because if I take it easy on my truck for a few days, and then I go WOT, I get a ton of black smoke out of the tailpipe. But this doesn’t happen if I go WOT frequently. Which means in my theory is, the oil is collecting somewhere and then is getting sucked into the engine at WOT. Once I deplete the pool of oil, it stops smoking. Typically when vehicles have bad rings, it will happen every time you go WOT.

I 'think' if this were the case it would be blue-tinted smoke not black. Just sounds like a big fuel dump, meaning the EQ ratio might be a bit rich. BB likely tuned it on the safe side if you don't have a wideband.

lucas287 · April 6, 2021

@truckguy82 this isn't helpful, but really just for comedic relief. Nothing beats the oil consumed in this episode of Roadkill 9 miles to the quart!

https://www.motortrend.com/news/roadkill-cleetus-mcfarland-toyota-hilux/

Grumpy Bear · April 6, 2021

40 minutes ago, truckguy82 said:

Also I found out the v6 uses a totally different pcv and afm manifold. Wonder if the v6’s are pretty much all oil consumption free.

I couldn't say and wish I knew. The V6's also don't suffer crazy torque converter failures either. They use a different one altogether. Truth is every motor uses some but over the normal OCI's we just can't measure it.

On the wife's 2.4 I used QSUD and decent filters on 7.5K OCI's and the rings gave up around 80K. A quart in 600 miles. We top end soaked that motor twice using the GM cleaner for this problem and several crankcase flushes and now have it down to a quart in 10K. Still using DEXOS1Gen2 just changing it every 2.5K with filter. As you can see I keep track and it took a good long while but we did get it freed up. Well better anyway.

Pepper was only on DEXOS1Gen2 for about 30K when I switched it to Red Line and then latter AMSOIL and it has always received 5K OCI's. I also cooled the motor down which cooled the oil down. Likely not such a big deal with AMSOIL but the mineral based DEXOS oils are not quite as robust in oxidation resistance. Never moves on the stick between changes with but a hint of oil dampness in the PCV hose. What both of those motors have in common are low tension rings.

When a motor starts using some oil and you run it softer it gets a soft coat of carbon on the piston top that burns off easy when you matt it. Another possible explanation for the smoke after taking it easy.

Kid you not. When Sugar Bears motor was pumping oil like a Texas oil well it never smoked. Weird.

Anyway, MOOK got me thinking about this some more.....

truckguy82 · April 6, 2021

2 hours ago, lucas287 said:

I 'think' if this were the case it would be blue-tinted smoke not black. Just sounds like a big fuel dump, meaning the EQ ratio might be a bit rich. BB likely tuned it on the safe side if you don't have a wideband.

Its not from running rich, have had several high hp cars with widebands.

it did the exact same thing before the BB tune.

It also highly variable, it all depends on how often I get on it. The only thing that could really be happening is something pooling up. I suppose it could be water in the muffler too, but that wouldn’t vaporize that fast. And our mufflers have a drain.

lucas287 · April 6, 2021

1 hour ago, truckguy82 said:

Its not from running rich

Maybe so! Hey @JONBLARC7 did you ever get yours to stop black smoking at WOT? Ran across a thread over on HP Tuners where you were trying to nail down EQ ratios to remedy it.

1 hour ago, truckguy82 said:

have had several high hp cars with widebands.

were they direct injected?

truckguy82 · April 6, 2021

40 minutes ago, lucas287 said:

Maybe so! Hey @JONBLARC7 did you ever get yours to stop black smoking at WOT? Ran across a thread over on HP Tuners where you were trying to nail down EQ ratios to remedy it.

were they direct injected?

I think you missed a key part

it only smokes a couple times when I haven’t driven it spirited in awhile.

when you’re WOT the ecu switches to open loop. Open loop means you’re not using sensor data and then adjusting based on those readings. The 02 sensors are bypassed. The fuel tables are pre-programmed and will be the same every time you put your foot down. If I was running rich, it would do it every time. I’m well aware of black smoke from running rich. I’m also well aware that a lot of cars produce black smoke when they first stomp the go pedal. This is not one of those circumstances.

i literally used to drive around with a laptop in my passenger seat for years and monitored the wideband afr, egt’s, oil pressure and temp, intake temp, intake pressure (fabbed up my own intake temp sensor setup)

granted it was obd1 and used a map sensor, so, maf’s, knock sensors, and multiple o2 sensors are greek to me

Edited April 6, 2021 by truckguy82