Burning oil at idle

I got an 83 Chevy Caprice (carbed 305). Its been burning oil at idle for some time now and i really want to get this last issue i have with the car fixed. It does it after about 10 minutes of idling i noticed. If i do have to sit idling somewhere, it helps (a little) if i bring the RPMS up to about 2,000, but thats just ridiculous to do all the time especially with my exhaust and even at that it still smokes a bit. The engine has 53,000 miles right now. Had 48,000 when i got it 3 years ago when it was driven by a little old lady. I hope i have nothing to do with this problem, i heard that commonly when teenagers get a hold of a little old lady car and they rev it harder then it usualy would that the piston rings get cracked and could cause this problem.

I'm just hoping that this is an issue of age and the fact that it sat with VERY minimal use for 7 years before i got it, rather than an issue of some serious internal work.

And one more thing, I'm gunna take a guess and say/hope its the valve stem seals (because they're easiest to replace lol). If i ran the engine with a valve cover off would i be able to notice/diagnose anything like oil build up maybe?

Two areas I would concentrate on are the drainback holes in the cylinder heads and possibly the PCV valve. Is there liquid oil in the air cleaner where the breather tube connects?

Two areas I would concentrate on are the drainback holes in the cylinder heads and possibly the PCV valve. Is there liquid oil in the air cleaner where the breather tube connects?

For these oil drainback holes, would it be as easy as blowing some compressed air through them to clean em out? Can i access those simply by taking the valve cover off or do the heads have to come off first?

The PCV valve has been replaced recently but i just checked that anyway and it still clicks when you shake it. BUT, i think i might finally be on to something!! I indeed found liquid oil where the breather tube connects (i found it on the filter.) So what does this do anyway and what does that mean?

For these oil drainback holes, would it be as easy as blowing some compressed air through them to clean em out? Can i access those simply by taking the valve cover off or do the heads have to come off first?

The PCV valve has been replaced recently but i just checked that anyway and it still clicks when you shake it. BUT, i think i might finally be on to something!! I indeed found liquid oil where the breather tube connects (i found it on the filter.) So what does this do anyway and what does that mean?


your engine is in need of rebuild,, excessive blowby...

your engine is in need of rebuild,, excessive blowby...

$hit...what a disaster. At least i know what it is i guess. Maybe a 350 swap is what i'll do, i just don't wanna get a rod wrappin piece of crap motor if i get it from a junkyard. I was thinking of maybe just doing a rebuild instead and beefing up my 305 altogether but i know you guys have always said you get more bang for your buck if you get a 350..

I just had to do more testing to determine my engines fate. I really can't believe its worn rings. So i made a video of everything just as a last determining factor for you guys to see. The engine does run fine still, but i guess this would explain the lack of power. I mean a friggen stock ford focus could beat this thing. I think it runs good enough to get by for a while though.

Here it is: http://www.youtube.com/watch?v=uWvs0kZFCJI

If the video quality is bad then it might still be processing, it'll clear up after thats done though.

your engine is in need of rebuild,, excessive blowby...

Keep your pants on, there are other causes of this as well. Any sort of crankcase pressurization will put oil in the breather - but sometimes it's not a blowby issue. A blown head gasket can do this if it's in the right place, as can a plugged PCV valve (which is why I asked).

BHW does your PCV valve receive a good dose of vacuum?

Keep your pants on, there are other causes of this as well. Any sort of crankcase pressurization will put oil in the breather - but sometimes it's not a blowby issue. A blown head gasket can do this if it's in the right place, as can a plugged PCV valve (which is why I asked).

BHW does your PCV valve receive a good dose of vacuum?

Are there really other causes?? Thats VERY good to know, i just got really worried there. I thought when you have a blown head gasket it causes whitish smoke? And mine is more white then blue i think as you might be able to see in my video..And also, my car has had a history of gaskets going bad left and right from when it was sitting around so maybe this could be it, along with other things like valve stem seals, who knows. Isn't there a way to tell by looking in the coolant tank? I haven't noticed any coolant loss at all, so maybe this isn't it. I'm running in circles now. I'd be better off preparing myself to take apart the engine and actually taking a look at everything.

So i just checked the smoke, i really wanna say its more close to a white color with a small hint of blue and i think it does smell like oil. It DOESNT smell like antifreeze,which has a sweet sort of maple syrup smell right?

I just wanna say a few things that might help. I don't get why it doesn't smoke when i'm driving, say stuck in traffic (if i do end up sitting absolutely still it will try to smoke however). I think its just when the car sits still with no movement for 5-10 minutes that it'll smoke. When i knew i had to idle somewhere i actually tried putting it in drive and using the E-brake to keep the car still..sure enough it started to smoke like always. So after i did this it brought me back to the question "why doesn't it smoke in traffic?" I figured that traffic is never usually at an absolute stand still, so when i had to idle somewhere i tried holding the RPMS to about 1,800-2000 RPM, this helped a little bit but it STILL smoked!....After all of this, i concluded that when the engine is under a load, it doesn't smoke..i'm not exactly sure what that means though...So using the conclusion, if i had to idle, i should leave it in D, use the E-brake and/or step on the brake, and bring the RPMS up as high as i can (without burning out lol). So if that indeed is correct that'll save me a little bit of embarrassment when i have to idle, but it'll be a chore to do lol.

It's probably burning oil no matter what speed you're at. If oil is getting into the cylinders at a constant rate, then it will look worse at idle because the engine isn't pumping as much air/fuel through it at idle to dilute the burned oil as when you are driving down the road at 2,000-2,500 rpm.

Also, the actual mixing of the exhaust with the outisde air is increased when you are driving too. At idle, you're not moving so the outside air is more stagnant and does not mix and dilute the exhaust smoke as quickly.

You can use some Smoke B Gone or Bardahl's No Smoke to help control oil loss, but definitely keep checking your oil level...running out of oil would be much worse than just smoke out the tail pipe. But eventually, you'll probably want to do either a rebuild or at least replace the valve guide seals.

Good luck!

It's probably burning oil no matter what speed you're at. If oil is getting into the cylinders at a constant rate, then it will look worse at idle because the engine isn't pumping as much air/fuel through it at idle to dilute the burned oil as when you are driving down the road at 2,000-2,500 rpm.

Also, the actual mixing of the exhaust with the outisde air is increased when you are driving too. At idle, you're not moving so the outside air is more stagnant and does not mix and dilute the exhaust smoke as quickly.

You can use some Smoke B Gone or Bardahl's No Smoke to help control oil loss, but definitely keep checking your oil level...running out of oil would be much worse than just smoke out the tail pipe. But eventually, you'll probably want to do either a rebuild or at least replace the valve guide seals.

Good luck!

Yeah it is actually burning oil all the time, it just the amount varies on how i drive obviously. I did a cold start this morning,opened the oil fill, and could see smoke immediately...

I did a cold start this morning,opened the oil fill, and could see smoke immediately...


that was the test I told you to do in a prior post of yours...'"with the oil fill cap off does it smoke" ????

this means combustion chamber gases are being driven past the rings into the crankcase..

with experience in this you can look at the puffs of blue smoke...is it all cylinders or one...

it is very possible with the vehicle sitting for a couple of years the compression rings got stuck...then because marvel mystery oil was not put into the plug holes of each cylinder to soak/lube the rings prior to first start up ,,,the rings scored the cylinder walls,,or cracked the rings..


ya sure the PCV and hoses going to/from as well as the ports that are on engine may be plugged causing this....but I thought you already got the PCV replaced and checked that it was sucking..ok..

that was the test I told you to do in a prior post of yours...'"with the oil fill cap off does it smoke" ????

this means combustion chamber gases are being driven past the rings into the crankcase..

with experience in this you can look at the puffs of blue smoke...is it all cylinders or one...

it is very possible with the vehicle sitting for a couple of years the compression rings got stuck...then because marvel mystery oil was not put into the plug holes of each cylinder to soak/lube the rings prior to first start up ,,,the rings scored the cylinder walls,,or cracked the rings..


ya sure the PCV and hoses going to/from as well as the ports that are on engine may be plugged causing this....but I thought you already got the PCV replaced and checked that it was sucking..ok..

The thing about the compression rings being stuck seems very possible. I'll put that on the top of my list of possible causes. And yes i have replaced the hoses and PCV, i rechecked that yesterday and its still working. Ahh well, the only thing i have money/time for is to put some "Restore" into my oil and see how that goes, i've heard some very convincing reviews from this stuff, but i dunno what any of you guys think about it.

UPDATE: decided i won't use RESTORE afterall lol. Like i said i found some very "positively" convincing reviews, but i just found some bad ones which are also just as convincing. So i'd rather be safe then sorry and just not use it. I'm due for an oil change, its been 3,000 miles and oil is medium/dark brown but not black. I've been using 10W-30, but i think i might get 15W-30 and see how that works, or would i notice a bigger difference with 20W-30?

Clean the head oil drainback holes as suggested, and look for sludge accumulation while the valve covers are off. If you find sludge, that's a good indication that the rings may be coked badly. Clean oil and frequent changes can help, along with a bit of moderately loaded driving once the engine is warm.

An older low mileage engine can also suffer from valve stem seal failure and guide oil leakage. This will contribute to oil burning.

I would avoid using the higher viscosity oil for now. Use a good quality mineral oil while the initial cleanup is underway. Eventually, you should be using 10W30 synthetic to help prevent sludge altogether, but it may be a waste for now. Once any heavy sludge is removed, switch to syn and good filters to help clean out remaining sludge.

Clean the head oil drainback holes as suggested, and look for sludge accumulation while the valve covers are off. If you find sludge, that's a good indication that the rings may be coked badly. Clean oil and frequent changes can help, along with a bit of moderately loaded driving once the engine is warm.

An older low mileage engine can also suffer from valve stem seal failure and guide oil leakage. This will contribute to oil burning.

I would avoid using the higher viscosity oil for now. Use a good quality mineral oil while the initial cleanup is underway. Eventually, you should be using 10W30 synthetic to help prevent sludge altogether, but it may be a waste for now. Once any heavy sludge is removed, switch to syn and good filters to help clean out remaining sludge.

It might be too late, just changed my oil yesterday from the 10W-30 synthetic [valvoline high mileage] (which i've used for about 2 oil changes) to 10W-40..and that may have made it worse because it left a puff of smoke after i took off from a stop after driving for a while and that has never really happened before. (The AC was on i'm not sure if that had anything to do with it because of the extra load on the engine maybe). But anyway..the big question is should i be getting some kind of oil additive? Or are those frowned upon. I'm not sure if its a rumor but i heard if you use "Restore Engine Additive" you need to KEEP using it?

It might be too late, just changed my oil yesterday from the 10W-30 synthetic [valvoline high mileage] (which i've used for about 2 oil changes) to 10W-40..and that may have made it worse because it left a puff of smoke after i took off from a stop after driving for a while and that has never really happened before. (The AC was on i'm not sure if that had anything to do with it because of the extra load on the engine maybe). But anyway..the big question is should i be getting some kind of oil additive? Or are those frowned upon. I'm not sure if its a rumor but i heard if you use "Restore Engine Additive" you need to KEEP using it?

I used engine restore twice on an engine like yours and it did not in any way reduce oil consumption....

the use of 10-40wt is not the correct oil for our engines,,GM advised that this oil must not be used....10-30wt oil is the correct oil...if you wish to try a heavier oil use 30wt in the hot weather then 10-30wt when cooler temps return...synthetic will reduce your oil problems and crankcase contaimination,,but it will cost twice as much for the product..and the reduction will be slight...


as you know , my opinon is , your engine needs lots of work..
no additive will correct this.

I used engine restore twice on an engine like yours and it did not in any way reduce oil consumption....

the use of 10-40wt is not the correct oil for our engines,,GM advised that this oil must not be used....10-30wt oil is the correct oil...if you wish to try a heavier oil use 30wt in the hot weather then 10-30wt when cooler temps return...synthetic will reduce your oil problems and crankcase contaimination,,but it will cost twice as much for the product..and the reduction will be slight...


as you know , my opinon is , your engine needs lots of work..
no additive will correct this.

Ugh this really sucks. If i end up spending loads of money to get this thing in perfect working order its not even worth it in the end, all of this work and the motor won't even repay me by being just "a little" fast. I hate being stuck with the worst engine ever put in this car. Maybe i'll swap it out with a 454 lol. But probably not, if anything it might have to be a 350 just because i know it works with my ECU or whatever and my transmission, and most important better gas mileage than the 454 i'd assume.

I'm still in school and with my income and the fact that its a carbed 305, its just not worth the money period. I'm still paying off that $1,350 transmission bill too. So at this rate i just gutta deal with it for a while and save for an engine that has potential...

And one more thing, whats going to happen with my engine because of the 10W-40?? You know i stood at autozone for 15 minutes debating on which oil to get..i always make the wrong decision in the end damnit. Because now when the engine idles (i'm not sure exactly how to describe it) but i can hear sort of a ticking noise, it sounds like you can actually hear the crankshaft dipping into the oil or something like that..ugh this is just bad...

if you really want to keep this vehicle ,,,you should not drive it during the winter...I would get another vehicle for winter use...do a plate swap/insurance swap...get a vehicle that is cheap to operate..then see if you can over the winter spring get some engine work done on the caprice..

if you really want to keep this vehicle ,,,you should not drive it during the winter...I would get another vehicle for winter use...do a plate swap/insurance swap...get a vehicle that is cheap to operate..then see if you can over the winter spring get some engine work done on the caprice..

You know thats exactly what i was thinking. I kind of think i really want to restore this car and the only way to do it is to get another car in the meantime..too bad my parents sold the old ford expedition not too long ago, coulda had yet another free car lol..my father even asked me if i wanted it, but he was thinking it was either the caprice or the expedition, as you can see i took the caprice but anyway i'll figure it out.

I have a 94 dodge shadow 2.5 litre that I just replaced the head with a brand new one back in April. Just recently and all of a sudden it started to run like a mac truck and upon investigating I have found oil in my air breather. What could cause this. This is a high mileage car.

I have a 94 dodge shadow 2.5 litre that I just replaced the head with a brand new one back in April. Just recently and all of a sudden it started to run like a mac truck and upon investigating I have found oil in my air breather. What could cause this. This is a high mileage car.

This is the Chevrolet Caprice forum.

As was mentioned, the most likely culprit for high oil consumption/burning oil on a smallblock chevy is the valve guide seals or worn valve guides themself. It's possible to change the valve seals without taking off the heads but I think you would need compressed air and an adapter to screw into the spark plugs to hold the valves shut. You could have poor ring seal but that is somewhat less likely. A compression test would indicate if you have bad ring seal.

How much oil are you burning? A quart every 500 miles or what? Also the valve covers are prone to leak on the chevy, but I think you said you are burning oil out the exhaust. Although a good valve cover seal will help the PCV system work better. Like someone else mentioned, you should only use a quality 10W-30 conventional oil only. Some years ago, around the time your engine was manufactured, GM said that 10-40 could cause ring sticking. A lot of people use to use 10-40 back then.It's probably a long shot but you might try going to a dealer and getting the exact PCV valve for this application. I would also want to check your engine vacuum. None of that will probably solve the problem but it might help. You probably have worn valve seals and valve guides and maybe bad ring seal.