So here's the scenario....

I drive a 2007 Jeep commander, 3.7L V-6, AWD. I'm just a few K short of 200K miles. I probably lose about a quart every 3 weeks. No oil leaks at all. Undercarriage is clean and dry. No "Check engine" light. No blue smoke. Passed my last DEQ last year and it was losing oil then as well.

It calls for 5-20 oil. I assume it's burning oil at a low rate, but higher than normal. Can I throw in a thicker oil that may burn less?

I change oil every 3,000 miles. In that time, I'll have added maybe 4 quarts to keep oil levels in safe range.

Tony.

Maybe try a 'high mileage' oil? You can certainly use a thicker oil if you wish, but I'm not sure that will result in the engine burning less oil.

You could possibly try a good synthetic if you are not already doing that.

quote:

I change oil every 3,000 miles. In that time, I'll have added maybe 4 quarts to keep oil levels in safe range.

So, 750 miles to a quart? (The time is irrelevant.) That isn't very good, but it is unlikely that going to a slightly heavier oil is going to help it substantially. On old engines, yeah, you could put Valvoline 50W racing oil, or gooey honey-like additives like STP, and help a little , but not modern engines with their tight clearances. You can't replace metal that has been worn away. For the cost of a good remanufactured engine, you can buy a lot of oil.

With that mileage and losing a quart every three weeks and it doesn’t leak, that engine is due an overhaul. Changing oil types/weights isn’t going to help.

We've been spoiled by newer, tight-clearance engines that burn little if any oil. I, and my brother before me (he bought it brand new) had a 1984 Chevy C-10, 7.4L (454) engine, the design of which dates back to the mid-1960s. It never got more than 900 miles to a quart even new, and closer to 700 with the car hauling and other heavy loads my brother was using it for. I liked to say it passed everything but a gas station.

quote:

Originally posted by egregore:
So, 750 miles to a quart? (The time is irrelevant.)

It's actually worse than that. It's 1 quart every 600 miles. You wouldn't put in an extra quart during the oil change at 3,000 miles.

If the engine has variable valve timing (I can't recall offhand), heavier oil than that specified will foul that up, then oil burning will be the least of your problems. Check your owner's manual for recommended viscosities vs. temperatures.

Thanks. I guess I'll just use what I've been using. I didn't see a difference with high mileage vs regular oil.

I won't be overhauling the engine. I'll simply buy another truck at that point (Ford F-150 or Toyota Tundra). Although I like my commander, it's one of the least supported Jeep models ever made. It was during that odd Mercedes/Chrysler era and has a NAG1 Mercedes transmission.

Tony.

Change your pvc valve. May make quite a difference on your Jeep. Did on my 2008, v6

Mine is a wrangler, but was surprised at how much it helped.

My old 2002 Lariat needed a quart every 300-400 miles in town but very little on extended highway (1-2k) ?

Sounds like worn piston rings. You probably don't want to replace the piston rings. You might want to try straight 40 weight motor oil if you can find it.

quote:

Originally posted by Broadside:
Sounds like worn piston rings. You probably don't want to replace the piston rings. You might want to try straight 40 weight motor oil if you can find it.

Bad idea. SAE 40 doesn’t have the additive package for car/truck engines. It’s suited for lawn equipment, etc.

I change oil for a few family and 4 of my own. High milage ones get 15w-40 in warm weather and oil users get a can of “Restore” as well. It helps, some, usually, to quiet old loose nosy engines and reduce oil use.

You don't have anything to lose by trying this at your next oil change.



The EPR is a mild cleaner you put that is supposed to clean deposits out of the ring grooves and help the rings to grip the cylinder walls tighter. Put it in the oil, run it about 20 minutes, then drain, fill with oil and add the MOA to the oil and the 44K to the gas tank. I have had the EPR "unstick" some variable valve timing gears before. If it doesn't do anything for you, you aren't out too much money. A couple of other things about EPR: it is very aromatic and volatile, so use it in a well ventilated area; and the oil, because it has been made so thin, will splash more than normal when you drain it.

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Originally posted by Dreamerx4:
Change your pvc valve. May make quite a difference on your Jeep. Did on my 2008, v6

I Wholeheartedly second that suggestion....PCV Valve.

It’s an inexpensive part at most automotive stores and can be easily and simply replaced by you.

Out little money if it’s not the valve. Quick fix if it is.

I would change the PCV valve and fill with a high mileage version of the weight oil recommended by the manufacturer. Whatever you do, don't switch to synthetic now if you've always run conventional oil. The engine will most likely spring leaks at the oil pan gasket and elsewhere.

Is it a dependable ride? The engine performs well?

I've driven a lot of really old cars. I would count myself lucky if I had a 13 yo car that is dependable. Money in the bank.

Buying a quart every three weeks / 600 miles shouldn't be a hardship for anybody. Buy it a case at a time from Costco or Walmart. Use what the owner's manual recommends.

Possibly worn or stuck rings. Do you have blue smoke under trailing throttle? You live with worn rings, stuck rings can be improved with quality "high mileage" formulated synthetic oil. High detergent properties in synthetic "high mileage" formulations can free the stuck rings, but not overnight. Might take a couple of oil changes, and costs you very little other than patience.