I have burned about 1/2 quart of oil in the last 6000 miles of mostly highway driving. I don't know if this is normal or not for this engine/year/miles. I have been doing long drain oil changes for a couple of years now with Mobil1 0w-40 synthetic and am getting great analysis reports. My pattern has been a 1 year oil change interval with a 6 month filter change with top up. Typical miles have been about 5K-6K in a year. I usually don't even check my oil other than to monitor for leaks. But this past year I have done about double the miles in half the time. On a trip to Florida I checked my oil and found it down the 1/2 quart and I know it was full the last time I changed the oil. There are absolutely no oil leaks and I just did a valve seal change about a year and a half ago. There is also no oil in the coolant. I pulled the plugs and posted the pictures below. Nothing on the plugs indicates oil burning that I can see. There is one plug (#6) with a small amount of black on the end but that is just carbon powder that easily brushed off and not any kind of oil burning accumulation. Typically I was doing 3K oil changes and so may not have even detected oil burning and I certainly am not used to having any of my vehicles burning oil.

I guess I am looking for some comment on the 3.0L V6 and its oil burning pattern. Is this a normal condition for these engines? I can't think of where the oil is going other than into the cylinders. The following pictures show the plugs in sets of two so that I could get good light on the tips. Their order is not firing order but just order from front to back and left and right.

1/2 quart on synthetic oil in 6,000 miles over the course of one year on a motor with 130k miles.. I'd say thats pretty good.

Personally I'd test the compression on those cylinders when you put new plugs in, that will give you an idea of how much blow by you've got if you think thats where the oil is going.

Those plugs look pretty normal as well.. <img src="/forums/images/graemlins/kewl.gif" alt="" />

I agree with Brendan - the plugs look great and 1/2 qt burned over 1 yr/6000 miles is nothing to be concerned about - particularly with synthetic oil.

Frank

More blow-by on synthetic, it's slippery stuff. I didn't think synthetic was recommended for older high milage engines?

Being down after a long drive when you dont usually see any changes in normal driving might be fuel trapped in the oil boiling off.

Its pretty typical to get some level of fuel contamination from short trip driving.

Kevin

Prior to doing my valve seals an oil analysis showed excess fuel in the oil (1.8%). When I did my valve seals I sent the injectors out for testing/cleaning. An oil analysis after the seal change showed normal fuel levels in the oil at <0.5% when <2.0 is considered acceptable. This year little driving has been the short trip kind. I certainly am not concerned about this level of oil consumption, especially when the plugs look so good, it's just not something I have noticed or experienced before. But when trying to get longer drain intervals, oil loss can cause some extra expense at top-up replacement and/or changing intervals. The PCV was replaced with the seal service and the addition of a clear plastic gas filter on the intake breather prevents oil from being sucked into the intake. The residue in the gas filter shows virtually no blow-by at this location.

I have been doing some research on oil volatility. It seems Amsoil is the only mfg'r promoting this but mostly against dino oils. I'm not sure how this may be the cause here.

Frank, do you think synthetic has a higher chance of oil consumption? I have not contacted Mobil1 yet to find their take on this. More research on the net showed no real standard for oil consumption except that North
American vehicles tend to have higher accepted amounts from their manufacturers, maybe related to larger tolerated manufacturing standards.

I still recommend Castrol GTX 10w-30 for the older engines.
It has a higher flash point and does not burn away as fast as other oils.

Not necessarily. If manufacturer's claims are true, synthetic oils should be more resistant to oil consumption issues, because the viscosity stays within a narrower range. The other side of the synthetic oil debate is the length of time and mileage that accrues before an oil change.... which can do damage to an engine whether it's seen synthetic or regular motor oil if the time/heat/mileage is too long for the particular oil. I've never been a fan of extended oil change intervals, but that's just my old-fashioned stubborness. I still use Pennzoil 10W-30 and change it every 3-5000 miles, but I see now some of the new cars are going 15,000 mile between changes.

Frank

Long drain intervals are certainly something I'm learning about and trying. The cost of synthetic does not justify regular 3k to 5k changes. Because this Montero sees low yearly mileage I do a 6 month filter change to be on the safe side considering the time the oil is in service. In this case, as the use of M1 0w-40 is new to me, I'm doing once per year oil analysis. The last report with 0w-40 was the best I'd ever had with any oil. I chose to change the oil now at 6k miles (with 1/2 qrt consumption) and only 6 months to mainly compare my last analysis with the same mileage as what this truck normally sees. In future I may just add the top-up and go the regular drain interval. I think 6000 miles for a synthetic is way too low to justify the expense. The main reason I like the 0w-40 is the little to none valve lash noise I had experienced on start-up with other oils. But it seems that at the 6000 mile point the adjuster noise creeped back a little, maybe because they can't tolerate dirt - who knows. As Bob Shaw pointed out the consumption may be the flash point. I have emailed M1 and Castrol to find the flashpoint of the 0w-40 and GTX 10w-30 as well as Castrol's 5w-50 synthetic.

There is no agreed on positives or negatives for any oil, just visit "bobistheoilguy" web site for expert confusion.

A friend of mine has a Subaru WRX that burns a lot of oil. She took it to the dealer complaining, and they said it was "normal" for that motor to burn 1 qt per 1000 miles <img src="/forums/images/graemlins/zombie.gif" alt="" />. I couldn't believe she was telling the truth until I looked it up, and sure enough there are hundreds of posts from around the globe on people with the same problem, and subaru giving the same response. So by Subaru standards, your motor is better then brand new! <img src="/forums/images/graemlins/ignore.gif" alt="" /> As for change intervals, I've often felt every 3k miles for changes was too much. Most people don't drive their vehicles under "severe" conditions all the time and tend to follow the "normal" driving intervals which are typically 6k-7.5k mile intervals. Popular Mechanics did a year long study on change intervals with conventional and synthetics following "severe" and "normal" intervals (3k and 6k on conv, and I think 5k and 10k on synth). At the start, they rebuilt all motors and measured everything, then at the end tore the motors down and measured for wear. There was little wear difference between all of the motors, so little that they determined it didn't matter what oil you used. Of course this was quite a few years ago, and they didn't include a fuel consumption factor in (which I think the synthetics would have shown a slight improvement in over conventional oil), and since all motors were freshly rebuilt, didn't factor in the extra "dirt" that a worn motor can create in the oil. If you're a casual off roader, I'd say change the oil after the off-road trip and use the longer "normal" interval between off-road trips.

It's better for the environment to have less oil to dispose of and the cost savings for little extra benefit will add up over the years.

The 87 FSM has normal usage changes at 7.5k miles for oil and every 15k miles for the filter and severe is 3k for oil and every 6k for the filter.

just my 2 cents <img src="/forums/images/graemlins/cheers.gif" alt="" />