The curious case of the missing oil(Suburban content inside)

Hey guys,

My daily driver 04 Suburban is due for an oil change according to the on board computer(alerted me today). Well on my way to the auto parts store for some oil, filter, and a windshield wiper for my wife's van the check oil level message came up. When I got home I checked the oil, and there was none on the dip stick! The truck doesn't smoke, and there is no oil on the driveway where I park. Where is it going? Truthfully I don't check the oil on this truck as it never seems to lose any over the change interval, and this thing is super reliable. I suppose I should keep an eye on it now. Any help on this is greatly appreciated. I suppose I should use the new oil for my change to keep the engine from blowing up.

In reply to Mazdax605:

PCV valve? A bad PCV valve can make an engine burn oil and you'll never see a puff of smoke. In fact, it's rare to see modern engines smoke when burning oil until they are absolutely wasted. See a lot of Equinox/Terrains burning a quart or 2 every 1000 miles and the exhaust out the pipe is clear.

My 07 Silverado will start to use oil at about 5k into the oil change. Not a drop before then and about two quarts from 5k to the oil life indicator saying it needs a change. The truck is probably telling me to start changing oil every 5k.

Oil change monitor says to change the oil every 6-8,000 miles, probably. Burn a liter every 4000 miles, and yo will be off the stick.

I love extended drain. I get to sell engines because of it.

Check your oil the same time you check you tires. You do, right.

I check mine every fillup.. so every two weeks. And my Disco goes the same thing Mazeduece, the oil stays in the crankcase until it gets dirty and then starts to disappear. This happens at around 3000 miles, so works out well

Common for newer style motors to use oil right about 4-6k miles after a change. If you captured that oil over that mileage with a catch can setup you would be surprised how much gets bypassed now to be burned....

So, change the oil, or just fill it up and change the filter?

Change the oil, you aren't burning "just spin on a filter" levels, not even close. Sounds like you're losing a quart every 3000 miles or less, well within normal for a 13 year old truck.

How often does it see wide open throttle? Sometimes it helps to blow the carbon out now and then, see how fast it will hit 80 on an uphill on ramp a few times a week.

Pull your cats. That's how I found I had bad valve seals.

The strange thing is it's never really lost any oil in the past. I wonder why now? 166k miles on the clock. I goose the truck every now and then just because I like the feel of the V8 and of course the sound.

Chris

Streetwiseguy wrote: Oil change monitor says to change the oil every 6-8,000 miles, probably. Burn a liter every 4000 miles, and yo will be off the stick. I love extended drain. I get to sell engines because of it.

I hate extended intervals. Most people scrap a car instead of fixing it.

The kind of people who believe in extended OCI tend to defer all other maintenance too, so the cars are admittedly not worth fixing. So in that sense, it's more like the car is committing suicide to get out of an abusive relationship.

Different oil not up to task of holding up (shearing out of grade) to the longish interval the oil life monitor is calibrated for? What oil are you running? O2 sensors drifted enough to cause fuel dilution? Or it could just be a gunked up PCV valve as mentioned.

Castrol gtx 5w30 is what I always use. I don't know how many miles it's been, but I have records of it. I will check in the morning though.

Chris

I'd recommend a synthetic if you're going off the factory oil life monitor.

Can I just swap to a synthetic now? What can you recommend for a synthetic?

Yes, no problem there. I don't think there's really a bad one out of the big names, I mainly run M1 because it works for me and Walmart sells it cheap.

FWIW there is an updated PCV valve for the 4.8/5.3/6.0 that has a teeny tiny orifice. We actually use it in other cars that have big lumpy cams that don't really tolerate the large "vacuum leak" of a normal PCV.

On the shop truck's 4.8, it used to burn 2-3 quarts between oil changes on synthetic. We switched it back to semi-synthetic and oil consumption is now half a quart in 5000. Curious but also not the only time we've killed oil consumption by moving away from synthetic in GM vehicles.

My Fiesta is nearing it's 10K/1yr.change. As recommended by Ford. The dipstick shows about a pint loss.

I have been doing the long change thing since '94.

All were relatively low miles, so that could be different on high mileage engines.

Today I am going to check the tires and the oil and top up the washer fluid.

A little trivia on oil consumption.

Plymouth flat head six. 5 qts. Burned of the first quart rapidly , then no more till change time. Ran it on 4 qts. thereafter.

Jeep, 226 flat head. Service bulletin, Cut 3/8" off the dipstick tube to prevent early burn off.

A friend had a Chevy van that we drove about 400 miles to a race. The oil light went on, and nothing on the stick, it took 3 quarts if I remember correctly. No signs of a leak, no smoke, no oil smell. It was weird. He sold the truck soon after.

So I am thoroughly confused now. Yesterday when I checked the oil, and found none on the stick I went to the garage, and found 2 loose quarts I had kicking around. I figured well if there is nothing on the stick then two quarts is better than nothing., I put them in, and we left for hockey practice. I neglected to check it after adding the oil(no idea why). Last night I had to go to work, and drove the truck the mile it takes me to pick up my service van. Then I drove it home at 3:30 AM. This morning I decided to check the oil before hockey practice, and wouldn't you know it has too much oil in it now. What gives? Does going from no oil on the stick to too much oil really fall in the 2 quarts range?

Drain back problem?

I am hesitant to admit that my 5.3 takes right about one quart (maybe a smidge more) to get it right about full when the add oil message appears. I shouldn't know that, because I'm clearly neglectful if I do, but I do.

Usually between 1 1/2 and 2qts if no oils on the dipstick. Ive never seen a 5.3 that doesnt have a rear main leak.