Not at all "regular" but I've noticed it three times in the last 2months.

I am colorblind and cant tell the color but I'd say it's blue smoke. Also I've asked two people and they confirmed.

The first time I noticed was after towing my 7000lb enclosed trailer 100miles to the race track. My wife likes to sit in the van with the a/c on. Extended idling time- many hours.Noticed it then. Blipped the throttle a couple times and it shot out a bit worse.

The 2nd time was 2 weeks ago, idling at a customer job site. No extended idling , no heavy trailer, nothing unusual. Same thing; light blue smoke at idle.

3rd time was this weekend. I can't remember the circumstances actually.

** a couple thoughts:
-the engine consumes about a quart per 1,000 miles, which lately is about every 1.5weeks. I do not ever usually notice blue smoke. Only at the 3 instances listed above. And there's plenty of time I'll be near it, idling, and no sign of smoke at all.
- so I add oil about every 3 -4 weeks. Which often means it's very low. Like, add two quarts and still needs another quart.
- a while back I noticed the oils consumption would decrease when I used 30 weight oil (5w30,10w30,sae 30). That was good to not have to add as much, but I noticed that it would get dark/dirty because I wasn't adding a fresh quart every week. So I switched back to 5w20.

Now im not big on brand names when it comes to oil. As long as it has current API then I'll buy it.

The first time I noticed the smoke it was after adding generic Orielly oil (2 quarts I believe).The 2nd and third time it was with Pennzoil.

I realize my my theory is stupid on its face, but I'm thinking maybe the intermittent smoke correlates with which oil I add. I'm wondering if Pennzoil makes the Orielly oil.
Ill buy two quarts of valvoline today and report back later this week.


Nonetheless id love to hear what you guys think about the intermittently smoke. AND what you think about my theory of oil brands smoking.

 

It sounds like a PCV valve problem, yes some oils will burn off faster than others.

Before you do anything take a quick engine health test. Get it warm and with the help from someone you trust remove the oil cap and have someone lock the brakes put it drive and give it some gas. If you get a large amount of oil vapor coming out of the oil full hole you have a engine problem. If you don't start checking all the hoses related to the PCV vent system, also make sure your dip stick is sealed. Any air that gets into the system will cause oil vapor to be pulled through the PVC valve and burned.

Denny

 

PCV, or valve guides/seals.

High vacuum will pull oil past the intake valve guides, and is more prevalent when the engine has seen high RPMs before idling it for a while because there's more oil up in the heads.

On the other hand, the PCV will do almost the same thing. The PCV valve could be stuck open.

 

It happened again yesterday. I towed the trailer 50 miles and then parked it for 5-6hrs, and then I drove it about 20 minutes of city driving and then left it idling for a half hour (wife was enjoying A/C). Upon getting back in I noticed oil smell. RS power mirror down to watch exhaust pipe and goose the throttle= puff of smoke.

Just a few days ago I had an oil change (using unknown brand and weight of oil) and they overfilled it. I saw they wrote "7 quarts" on the work order and I pulled the dipstick afterwards.

 

Could be oil being thrown up into the cylinders, and then the high vacuum of idling for a while pulls it into the combustion chamber.

But, at 314K miles, your valve seals might be toast. See other thread here about that - does it puff when you first start it after sitting a day?

 

With that many miles on a gas motor I wouldn't be to concerned unless it starts using a lot of oil. My 2000 V10 work truck used 1 quart every 2K from new and the guy I sold it to ran it up to 385K miles before it shot a plug so they retired it last year. It was still using a quart every 2K at that time using Mobel I, there were times I thought it was smoking but the oil consumption remained the same.

Denny

 

Seems like a few people are asking if it does it at startup after sitting for a while. ill try to keep an eye on that.

In the mornings I fire it up before the sun is out so there's no reasonable way I could do it after sitting overnight. But there's a time or two each day where it'll sit for quite a few hours before I start it. Will that suffice for what you all are referring to?

 

you mention concern- my only concern is that it's embarrassing, and a little concerned by the smell also. I do have some concern about engine longevity but not much.

 

Yes, that'll do - any time for a few hours, to left the oil in the heads leak past the valve guides and hit the intake valves.

 

I spent some time working on my van yesterday to diagnose and replace the relay for the aux battery.
I also added two quarts of oil because I hadn’t checked it in a few weeks. After two quarts it was about 1/8” overfilled. No big deal.
Upon restarting it I wanted to let it warm up and I was climbing around with volt meter checking my results.
Next thing I knew I was completely under the van checking everything.
Everything. Exhaust manifold studs, suspension, exhaust system, everything.
Next thing I know it had been a while- felt like a half hour or so.
I had worked my way to the rear and while I was there I noticed the idle got funny for a moment and then it suddenly began smoking blue out the tailpipe.
The idle was funny for about 10 seconds but the blue smoke continued for a minute or so until I got up and turned it off.

Anyone here find a clue in this crazy story?

 

Yeah, you're crazy

All joking aside - check the PCV system and make sure the PCV valve rattles. Somewhere, it's getting a lot of oil in the intake all of a sudden. Valve guides seep - and allow oil to get onto the intake and exhaust valves over time. But not all at once, like "hey everything's fine, we're idling fine" and then whammo! Idle goes to crap.

Somehow, someway, oil is getting into the intake side of the motor.

On the other hand, too much oil in the exhaust could fool the O2 sensors and ruin the idle.

 

I'm thinking that there is a low spot in the PCV line and when it fills with oil it gets pulled into the intake causing your rough idle and smoking.

Denny

 

I’m getting more and more curious about the PCV system. On the flip side; my fingernails are still dirty from the spark plug job 3 weekends ago...

 

 

Changing the PCV valve would not hurt. I'd also try running a High Mileage 5w-30 oil in it for a couple oil changes. The extra viscosity when hot isn't going to do anything but help and the high mileage oil has seal conditioners in it which may help to reduce some of the leakage if it is the valve guide seals.