Good oil in a late model oil burner

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28
Location
NJ
I'm wondering what happens to the oil that is burned in a well-tuned catalyst-equipped engine. Does is deposit on the exhaust valves, the exhaust manifolds, cat converters, etc. or is it blown out into the air? Also, what exactly deposits? I'd imagine primarily the HCs would deposit as coke or whatever, but I've also read that the Phos (from the ZDDP) may deposit and foul the cats. This is why the EPA is concerned with Phos levels in oils. This question is not just academic, but really a practical one since my almost new 2001 Trooper burns a decent amount of oil. Vehicle has approx. 28,000 miles on it right now. It burns approx. one quart in 6000 miles. The engine is a 3.5 liter gasoline engine with a published 215 HP rating. Engine runs perfectly. It recently passed a NJ state dynomometer emmissions test. I'm concerned that as the miles roll on and the oil burns through, that the burnt oil may have negative impact on the engine's performance and the engine's emmissions. It burns approx. one quart in 6000 miles. I've read lots of stories (both here at BITOG, and elsewhere) about other late-model Troopers burning more significant amounts. Current oil is Mobil 1 0W-40. Are synthetics better or worse than dinos as far as leaving deposits? How about comparing regular dinos to high-additive dinos like the 15W-40 HD oils? I'm thinking that I (or rather my car's engine) would be better off with maybe a regular Pennzoil or some other regular dino rather that the PAO from Mobil 1.
 
One quart in 6000 miles isn't too bad; one quart in 2000 miles is bad. It doesn't matter whether you burn syn or dino, it's the addatives, such as the phosperous that you mentioned, that do most of the damage. The cat and O2 sensors are most susceptable to damage from oil burning, I understand. Basicially I wouldn't worry too much about the oil consumption of your Trooper at this point, but you might try different oils to see which is burned least.
 
If I were you I'd look into oil specs for the amount of Sulfated Ash. As far as I know, this is an indicator of how much unwanted (solid?) junk is left after the oil burns. I don't know about the engine, but in the long run, burning oil cannot be good for catalytic converters.
 
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2,569
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College Dorm...
Alright, let's see if I can straighten this out... First off, the sulfated ash isssue is overblow. Basically, additives in oils, such as detergents and anti-wear/extreme pressure additives contain metallo-organic properties. These "properties" leave a residue behind after three steps: 1. Burning of the oil. 2. Treating the burnt residue with sulfuric acid. 3. Burning the "treated" residue Simply put...the higher the amount of anti-wear and extreme pressure additives (which we all want in our oils!)...the higher the sulfated ash level. What people who say this is a big issue fail to realize is there are strict limits placed on the sulfated ash content in oils. While high amounts of AW/EP additives are good, they contribute to sulfated ash, which contributes to combustion chamber deposits and even top ring wear. The amount of sulfated ash in HDEO's is now around 1.3%...not enough to cause any problems. Truth be told, I bet that's why you now see molybdenum appearing in HDEO's...they need something else to add to give comparable protection to previous formulations that had higher levels of zinc/phorphorus and didn't have to deal with new regulations. Phosphorus content in HD oils can affect modern catalytic converters, but it would take a very long time to do so. Your really not burning that much oil at all (many people would be very happy with this consumption level!) Feel free to experiment...the 15w-40's are thicker at operating temps than passenger-car 40 weights, thus possibly deceasing consumption a little more. [ September 19, 2003, 07:34 PM: Message edited by: Jelly ]
 
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961
Location
Tacoma ,WA
quote:
Originally posted by williar: One quart in 6000 miles isn't too bad; one quart in 2000 miles is bad. It doesn't matter whether you burn syn or dino, it's the addatives, such as the phosperous that you mentioned, that do most of the damage. The cat and O2 sensors are most susceptable to damage from oil burning, I understand. Basicially I wouldn't worry too much about the oil consumption of your Trooper at this point, but you might try different oils to see which is burned least.
HA! My wifes car burns 1 quart of oil every 60 miles ( not a typo) heck we only wish it were every 600 miles!
 
Messages
125
Location
Virginia
I cut the oil use about in half from 1qt/1000-1500 miles to 1 qt every 3000 miles, in my sons beater Buick with the 3.8 v6, by switching it from Mobil 1 10/30 to Chevron Sup 10/40. Don't know if it is because of the viscosity change,synthethic to mineral etc. But it sure seems to like it.
 

JTK

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13,516
Location
Buffalo, NY
Craig L- 1qt/6Kmi really is quite good for these engines. My 2002 rodeo 3.2 (same engine, different crank) consumes about 1qt/4Kmi. The bad oil control ring issue on these engines was supposedly worked out by 2000, so there shouldnt be any worries there. I'm currently running a 3qt Mobil Drive Clean & 2qt M1 10w-30 mix. Havent used a noticable amount of that yet in 500mi. My 2002 manual lists 10w-30 as the "preferred viscosity", but 15w-40, 20w-40 or even 20w-50 [Eek!] can be used in temps above 10degF. About the only thing that carbons up on these engines is the EGR system. Fuel system cleaners keep that at bay though. If not, it's easy to clean w/ some carb cleaner [Wink] G/luck Joel
 

Craig L

Thread starter
Messages
28
Location
NJ
Thanks to everyone for their replies. I guess I don't have too much to worry about as far as oil burning is concerned. I still wonder, though, where all the oil goes that's burned in a real oil burner...how much makes it out the tailpipe, how much gets burned in the cat, how much it wears down the cat, how much gets deposited inside the exhaust pipes, how much in the combustion chamber, etc. JTK - yeah, I checked the EGR valve a month or so ago, it was very clean. I soaked it (the insides only) in some toluene anyway to make sure it was spotless.
 
Messages
263
Location
DFW, TX
I disagree with Jelly about using HDMO in a gasser. The HDMO ash levels are typically between 1.3% - 1.5%. The gasser oils are in the .7% - 1.2%. IMHO, that is a big difference for a car that burns oil. I would NOT be concerned if it burned considerably less oil. For instance, let's take Chevron's oils. The PCMO (10w40) oil has a ash of .94%. The HDMO (15w40) is 1.35%. Let's say you run each of the above oils in two cars of the same model for 75k miles burning 1 qt every 6k miles. I'd bet a whole lot of money, the one with the 1.35% would have considerably more "junk" in the combustion chamber. Remember this "junk" leads to pre-ignition which leads to engine death. I would think if the ash content was not that important, it wouldn't be in the spec sheet. I also think it's worth mentioning that M1 has an ash content of 1.2%.
 
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2,569
Location
College Dorm...
Chris, It's cool you disagree with me...kinda interesting to see the other point of view explaned [Big Grin] . With that said though, I still think the sulfated ash issue is overblown. Yes, I do agree with you that deposits will be greater with a HDEO 15w-40, but without going into a big explanation, I'll end with this... All the big-name HDEO's are API SL certified for gas engines, which means they are safe for use...I don't believe the slighly higher ash level will cause any problems (Heck, as you alluded to, syntheic oils have almost the same ash level!)
 
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