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jwood1016 said:
I put in cheap $3 5w30 oil versus the usual 7 dollar Mobil oil and the burn rate decreased a lot. Whats that all about?
I assume that the expensive oil is a full synthetic and I also assume that the cheap $3 oil is NOT a full synthetic.
 

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motor burns nothing while on highway it burns it up in traffic
 

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HA HA.

This is interesting. I was going to make my own post about this very same thing.
my trooper has burned a ton of oil since I hit about 110k miles. I burned rotella synthetic 5w40 for two years and consumption only got worse over time.

about 4 months ago I started using Wal-mart brand high mileage 10w40 in the truck and I have gone from about 200 to 300 miles per quart to over 500 miles per quart on the highway. Around this rural area and being stuck in traffic consumption is worse still though.
 

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srsmillwork said:
motor burns nothing while on highway it burns it up in traffic
When I had 2002 Rodeo it burned oil only on freeways when I was driving above 60 MPH. The same had been true for my Axiom before I switched to *-40 oils. Both vehicles never burned oil in slow traffic.
 

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Guys....I am experiencing the exact same situation with oil burning more and more. My '99 Trooper has just over 200K miles and I've been using Rotella Synthetic for the last 40-50K miles.

I only get about 200 miles/qt when on the highway and/or around town. Thats way down from the 400-500 miles I used to get. While my rig is technically "retired" b/c I only use it for hunting/fishing/trail trips, I'm tire of spending this much and risking running low and forgetting about it.

I may go back to a quality dino as well. Thoughts?
 

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ducktrooper,

Try the high mileage wal-mart 10-40 for a while and see if it helps any. My trooper is used pretty much as a weekend vehicle now and for camping trips etc. But our camping trips are over 200 miles one way typically.
 

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Ok, none of the mechanics have appeared to have chimed in so I'm going to try to jump start this: Chemical and Mechanical Engineering of oil:

"Cheap" oil - little, if any, detergent. promotes "buildup". This buildup is not bad in all vehicles. depends on the design of oil passages. Lots of old (pre-80's) low RPM cars seem to like this kind. Quaker State used to advertise this "feature" in different terms.

Expensive oil - usually more detergents to prevent or dissolve buildup and "sludge". Newer engines that have lots of oil passages in "hot spots" do well with it because those passages can "cook" the oil and cause sludge/excessive-buildup/clogged-passages.

Synthetics - unlikely to promote buildup, varying amounts of detergents. Great with new cars, use with caution in older engines.

So Synthetics best, right? Well no. Case in point, there is a guy that drove his model A all over the country (and if I can find a link, I'll post it) for kicks. He started putting something like Mobile 1 in it and it started using lots of oil fast. He went back to straight 30wt non detergent and within a few thousand miles had almost completely stopped using oil. Didn't seem to leak as much either.

All engines that "burn" oil are letting it in the combustion chamber 1 of 3 ways: seep past the rings, seep past the valves, or a "failure" of some kind. The gap around the rings is (should be) microscopic and if the oil "seasons" the cylinders, little of the oil gets past. Add detergent, and you loose that seasoning. Think cast iron skillet. Same with the valves.

If I had a "I bought it new" car, I'd use Mobile 1 (which I have and do). If I have 200000 mile car that ran good, I'd try to stick with what it was used too (which I have and do) unless I detect a problem with sludge or similar.

Past 75k, if I ever think an engine has "cooked" (not fully overheated, but definitely got hotter than normal for an unhealthy amount of time, I would do an oil change with a heavy on the detergent oil, then probably go back to what it was used to in order to bring back the "buildup".

Hopefully that is enough to get a mechanic to chime in and point out the errors in my little essay. Ciao.
 

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BAMF said:
I put in cheap $3 5w30 oil versus the usual 7 dollar Mobil oil and the burn rate decreased a lot. Whats that all about?
Probably because you tightened the drain plug/filter enough this time.
 

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justwork said:
Probably because you tightened the drain plug/filter enough this time.
Now that's funny.

But really, my Rodeo also goes through Mobil-1 5w-30 synthetic faster than it does 10w-30 conventional oil. It runs fine on either, and given the miles, I don't think running the synthetic is really doing any more for the engine than the conventional oil. I say that, unless you're having issues w/ oil getting to the top end quick enough, stick w/ a heavier conventional oil, and just stay on top of regular oil/filter changes.
 

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My vehicle, also, was using Mobil1 5w-30, like 0.5 qt per 1000 miles. When I switched to Mobil1 0W-40 and 5W-40, the oil consumption decreased to zero. May be Mobil1 5w-30 is simply not suitable oil for Isuzus, but I do not know why and what is so special about it.
 
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