Question for Engine Gurus
 

My DD pickup has started burning oil. About a quart every 1,500 miles at this point. Started about 10k miles ago and has progressively gotten worse.

I've been running 10 w 30 oil in it since new. If I changed to 10 w 40, would that likely reduce the oil consumption a bit - or make no difference?

doubt that would make a noticeable difference, Travis...try Castrol 20W-50...but not sure it's worth the cost.

I've got 14-yr old Nissan SUV (3.5L V-6) with 157K mi's doing the same thing...I use the cheapest dino oil I can find (Target, Walmart).

Gary

Yeah, I was wondering a higher viscosity might slow it down. Did you try a higher viscosity on your Nissan? If so, did it help?

My truck is a quad cab '07 Colorado I bought new 11 years ago. It's got 170k miles on it. Truck is in great shape - just has a bunch of miles - and I've got a couple kids in high school, so I was planning on keeping it and overhauling the engine at 200k.

With the oil consumption starting to ramp up, I'm getting a little worried it'll reach the point of smoking the cat (which I'd rather not see happen). If a higher viscosity would help, I'd try that just help the cat. If not, then that overhaul may need to happen before 200k.

I'll probably try it on the next oil change and see what it does. Figured somebody had to have already tried this trick.

Is it burning oil? Or leaking oil?

It might help if you give a little more information than "it has an engine" and it's not a Corvette (hence, posting under "other cars"). Oh, and it's "burning oil." Just sayin'.

Thicker oil might slow down the issue. It won't actually "fix" whatever's wrong with it, though, and it could cause more damage (perhaps).

Some kind of "engine treatment" which includes seal conditioners and "stop leak" additives might be a better choice.

Do you have an IR (point and shoot) thermometer?

Keep track of the temps of the (upstream) cat housings. If one side is hotter than the other, the oil leak/burning is more (maybe all) in the bank with the hotter cat.

You can do a before/after test when changing viscosity and see if it lowers the temps of the cats.

It's not leaking any oil, and never has, which has been nice. So it's burning it. Not enough to smoke visibly, but enough to easily detect monitoring the dipstick.

It only has one bank of cats (single exhaust).

Two things.

First, if you want to know if thicker oil helps or hurts, measure the temp of your cat (the upper cat, there's still two) after a long drive, or check it a few times. Change to thicker oil and continue observing the temp of the cat. If it gets cooler with thicker oil, the thicker oil helped. Keeping an eye on the temp of the cat can tell you if you're oil consumption issue is really a problem for the cat, or if it's not enough to matter.

Second, if you're planing to do a full rebuild anyway, perhaps as an educational exercise with your son, you don't have much to lose in "field testing" one of those bottles of snake oil that claim to "cure" oil consumption and smoky exhaust. If you do that, consider it a TOFTT moment and report on the success/failure of the product.

At 170K miles, I'd think that the valve stem seals and/or piston rings are showing wear and are allowing oil to be drawn into the combustion chambers. It may not be severe enough at this point that the engine is smoking, but just enough to be a quart every 1500 miles. keep in mind, that back around 2001-2002, the Corvette LS engines had those "low tension" piston rings that were causing "excess oil consumption", and that was from day one, zero miles.....

I would go slow on adding anything that swells the seals , because, well now your seals no longer fit. Not a problem if you are good at replacing seals , or have nothing to loose in the first place, with a totally shot engine.

in my younger days I burned a lot of oil thrashing an old MG around town. I didn't know much about cause and repair, but knew where to buy recycled oil in big cans and motor honey, STP and the like. Luckily, the plugs were easy to get to and clean.

PCV system might be letting oil by.

what engine is in it?

If it's an LS with DoD/AFM, might want to swap cams to a non-DoD cam and lifters, install a new valley pan (I think its either the LS3/2 I can't remember what I did) that has better PCV action than stock. But it cured my 160k mile '09 Suburban's 5.3 oil consumption.

It's the 3.7 liter inline 5.

Oh-h-h.......

What year is it?? Canyon/Colorado engine? 2004-2006, they were known to have issues with a bad run of cylinder heads. I had a 2005 Canyon 4x4, and it was good for me, for 10 years, and 50,000 miles, but toward the end of my ownership, I was a little nervous about it...

It's an '07 quad cab Colorado. I've owned it since new, so have had it 11 years now. Been a good rig and trouble-free, but it's approaching 170k miles.

I'd try the PCV first as White Out mentioned, it's the cheapest/easiest thing that could be the culprit. Especially if it's all of a sudden, worn engine components typically start slow and get worse, not just all of a sudden typically.

Yeah, I thought the pcv idea was a good one - and one that's quick/easy to do. Will definitely do that.

The other rec on checking cat temps, I don't a scanner to do that, but a buddy of mine does, and I'm going to borrow it and check that as well.

If it's an '07, you should have the "good" cylinder head. As mentioned, I'd look into the PCV system.

Good luck!