unusual oil consumption

[93medusa]

Hello all,
The other day my oil light came on...just a few weeks after my oil change. I checked my oil and it was down like 2 quarts. I know that the filter and the plug are on good, and it is not leaking from either of those locations. One thing that I thought might be related is the fact that my tailpipes get very sooty on the insides, and there is a little bit of smoke that comes from them. What is this a symptom of?

I purchased this car a while back, but have just started driving it regularly, so these problems are just starting to present themselves. It is a 93 MTX, sho shop catted-y, cat back, and cold air intake are the only engine mods on it. I don't believe it has an LPM, but it might, I need to check that. However, I don't think that any of those mods should effect oil consumption.

Any help from the forum's collective experience would be vastly appreciated.

thanks guys

 

[yamahaSHO]

What color is the smoke? If it is blue, you are burning oil. That is most likely caused by severly worn piston rings. You may want to run a compression test on the motor.

 

[MyFirstSHO]

If you are have no external oil leaks, like at the front, rear, or sides of the oil pan, You may have an internal oil leak. When do you see the smoke? At start up or WOT (wide open throttle)? Remember, in this cold weather we are having now, EVERY single car on the road emits a thick white cloud of smoke under acceleration. This is called steam, this means your engine is actually working correctly. If, like yamahasho mentioned, the smoke is blue, it is in fact oil being burned, either by oil leaking past worn valve guide seals, or leaking past worn piston rings. Does it smoke right when you start it up (cold, hot)? Or does it only smoke when you are mashin the gas? Or does it constintly smoke, even while idling? When it blows blue smoke, will tell you which is your problem.

You can also burn oil and never actually see it. Take my work van for example, its a 98 Chevy 2500 cargo van with the vortec 5.7L. Its got 110K+ miles on it. I've Never seen blue smoke come out of the tail pipes, and the oil pan is as spotless as the day it rolled off the factory. Yet, I check the oil every 2000 miles or so and its at least 1 qt low. Same thing with my brothers 87 S10 pickup with 135K miles, only that thing will burn 1 qt every 500 miles yet it doesn't drip any oil and I have yet to see blue smoke come out the tailpipe. All cars "burn", or use oil. Its when you actually SEE the blue smoke, then you know something is not right.

HTH beer

 

[93medusa]

Hey guys,
Thanks for the responses. I'll have to study the smoking a little more. I have only noticed the smoking while idling in the driveway warming up, otherwise. Otherwise I am driving the car,so it is hard to take notice of that sort of thing. I'll see if I can get a roomate to drive it around so I can observe. I also don't believe that it is blue, more like white. For anyone that knows Greg Raciti (founder of shoforum) this is his old car. it's in great shape, and I am just hoping that there is nothing to extreme wrong with it. My old SHO, a 95 went through about a quart every 2000 miles. So I am familiar with normal oil consumption. I think however my question might have been answered in another thread. I recently switched the car over to Mobil 1 http://www.shoforum.com/ubb/ultimatebb.php?ubb=get_topic;f=17;t=009836

once again, thanks guys

 

[jelloslug]

Becuse of the way the y-pipe is configured some of the places that oil can leak from will almost never show up as spots on your driveway. My rear cam seal leaks quiet a bit, but the oil never gets past the converters before it's burnt off.

 

[billyshoe]

Its not at all unusual for a sho to burn large quaintities of oil at 80,000mi & up depending upon the history of severe use it has been subject to. This is mainly due to blow-by carbon build up in the ring groves causing the oil scraper rings to become stuck. Inadequit PVC is a large part of this problem. This carbon will not dissolve with oil additives no matter what thier claims of cleaning abilities are. Pistons grooves need to be hand cleaned or replaced. This means for all practical purposes the engine is worn out & need of ring job or replacement.

 

[billyshoe]

For a perspective on leakage, there are 36,000 drops of oil in a quart. Do you have that much of a leak? I doubt it.

 

[Rob94]

While it's not unusual, I must be lucky. Over 182,000 miles on my 94 and she doesn't burn a drop.

 

[Off Road SHO]

billyshoe:
For a perspective on leakage, there are 36,000 drops of oil in a quart.

I hope somebody figured that out scientifically and not by counting.


And most "top" oils will eventually clean out the coked oil rings enough to scrape again, just not like new. Marvel Mystery oil works as does 1/2 quart of ATX fuid added at every oil change. Lucas also make a disolver oil product but I can't remember what they call it.

I'm not a real fan of additives, I would rather see more frequent oil changes (done when oil is hot and thoroughly circulated).


Tom

 

[billyshoe]

Luck does'nt have much to do with it. If you turn the crank 7000 rpm for extended periods on a already worn but happy engine, the blow-by heat will fry the oil that is already been forced past the worn rings into the grooves from High crankcase pressures. The other crankcase oil vapors distill in the intake puddling in both sides of the plenum allowing even more oil by-products to deposit behind the rings. At the same time the engine is running like a top. Plenty of power to scare you're buddies. It will still top 140mph. It will burn more oil the harder you run it. If you drive like a ***** it will use a lesser, tolerable amount of oil. The catylitic converters heated to operating temps do a wonderful job of eliminating the smoke from a rearview mirror standpoint. This is a discription of a typical used up SHO engine. About 36000 drops is a accurate estimate for 10w30 quart equivlant. I have decided this is not a ******** figure and don't have any desire to verify the aquired info.

 

[Lurch]

billyshoe:
It will burn more oil the harder you run it. If you drive like a ***** it will use a lesser, tolerable amount of oil. The catylitic converters heated to operating temps do a wonderful job of eliminating the smoke from a rearview mirror standpoint. This is a discription of a typical used up SHO engine.

I don't like the sound of that.

My SHO seems to be doing a thing where it burns a small amount of oil under normal driving conditions, but if I really get after it for 3 or 4 times the oil level will drop more quickly. For example, with a little spirited driving and lots of highway cruising, my SHO has burnt about 1/4 quart in the last 300 or so miles. I say burnt because I see no evidence of a leak, yet I see no/smell no oil smoke either. Not sure what I thought the problem was, but I certainly don't want it to be rings!

 

[billyshoe]

Lurch:

Originally posted by billyshoe:
[qb]It will burn more oil the harder you run it. If you drive like a ***** it will use a lesser, tolerable amount of oil. The catylitic converters heated to operating temps do a wonderful job of eliminating the smoke from a rearview mirror standpoint. This is a discription of a typical used up SHO engine.

I don't like the sound of that.

I was misquoted, I said drive like a "PUUSAY", not *****.

 

[Lurch]

nah, your original post says ******. I didn't censor it.

 

[MyFirstSHO]

FWIW, My SHO has 114K miles and I drive it like I stole it. My SHO uses 1/4 qt every 1000 miles, when Im mad, and uses hardly any every 1000 miles when Im tame.

I guess I lucked out too.

(well I wouldnt of bought it if it were an oil burning monster that would be pretty slap )