Cleaner oil drains with premium gas

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I have done this more than once. With my last toyota truck w/4cyl engine. I ran premuim Shell fuel. I used castrol GTX oil change every 3-4k miles. Oil looked almost like I put it in. This continued for 55-60k miles. Then I started using mid/lower grade Shell fuel-the oil was darker to very dark. I had done this because of expenses at the time -and I figured no big deal.This was for about 20k miles. At approx 85-90k miles I went back to premium. After the 2nd or 3rd oil change oil was once again much like fresher oil/honey color. I owned the truck up into the 210k range before selling. never burned a drop of oil. Oil was still looking same color.I contribute to better detergents in the fuel (guessing) but I am convinced my engine stayed cleaner/ran cleaner because of it. My wifes CRV had same oil @ 3k changes w/premuim fuel. Her oil always looked like I just put it in. My daughters Civic oil was always black at 3k miles-same brand oil but low grade fuel. All 3 of these vechicles were bought new. Just an observation. BTW I used most all that used oil in my chain saw bar oilers for our fire places/wood stoves.
 
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I really have absolutely no idea why the octane content of your fuel would change your fuel color. I mean maybe if all those vehicles you listed were carburetted and had a terrible tune but even then ..... nope.
 
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The Top-tier FAQ states that all grades of fuel have to have the same level of additives to get top-tier certified. So it is just a myth and old phony marketing that premium contains more additives. I don't think the fuel is inherently "worse" or dirtier but rather that your engines are changing timing to be as close to knock as possible. For this system to make sense, there must be a few knocks that the sensors detect once in ahwile as it shifts the timing to see what it can get away with. You don't tell your car I put in premium this tank; it automatically detect. So the suboptimal combustion could be creating the extra color in your oil. End result maybe the same to you, it's a "dirtier" result; but my opinion is really the lower-grade fuel itself could've run just as cleanly if the engine management treated it fully differently rather then asking the management system to find the timing point.
 
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gathermewool

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Some data-logs showing timing and fueling would be amazing! I've actually thought about using a slightly higher octane in our Civic to see what the effect might be, but it's my wife's car and I know she wouldn't know the difference even if it added 30% more HP, not because she's dumb, but because she couldn't care less. It might be worth comparing the effect on the oil, however... For the OP: I don't think you have anything to worry about with such anti-BITOG short intervals.
 
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Originally Posted By: raytseng
The Top-tier FAQ states that all grades of fuel have to have the same level of additives to get top-tier certified. So it is just a myth and old phony marketing that premium contains more additives.
Not according to Shell. http://www.shell.us/products-services/shell-for-motorists/fuels/vpower/faq.html Q. Since the Shell Nitrogen Enriched Gasolines clean up engine gunk in all three grades, what makes Shell V-Power different? A. Shell V-Power is our most technically advanced gasoline. It contains our highest octane gasoline as well as the highest concentration of our patented Shell Nitrogen Enriched Cleaning System. With five times the cleaning agents required by federal standards, Shell V-Power cleans up performance-robbing gunk even faster than Shell Regular grade gasoline in both conventional and modern, direct injection engines.
 
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Originally Posted By: cookieman214
Originally Posted By: raytseng
The Top-tier FAQ states that all grades of fuel have to have the same level of additives to get top-tier certified. So it is just a myth and old phony marketing that premium contains more additives.
Not according to Shell. http://www.shell.us/products-services/shell-for-motorists/fuels/vpower/faq.html Q. Since the Shell Nitrogen Enriched Gasolines clean up engine gunk in all three grades, what makes Shell V-Power different? A. Shell V-Power is our most technically advanced gasoline. It contains our highest octane gasoline as well as the highest concentration of our patented Shell Nitrogen Enriched Cleaning System. With five times the cleaning agents required by federal standards, Shell V-Power cleans up performance-robbing gunk even faster than Shell Regular grade gasoline in both conventional and modern, direct injection engines.
This, I actually called Shell some years ago to ask about the difference between grades. As I remember the call I was transferred once and a fellow picked up the phone who claimed to be a lab tech. He told me that the Regular grade contained twice the federal minimum amount of detergents for top tier gasoline, the mid grade had three times that minimum and the Premium grade had five times the minimum. I realize this is very anecdotal but thought I'd add my 2 cents...... well, maybe it's only worth half that. :-)
 
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Originally Posted By: raytseng
The Top-tier FAQ states that all grades of fuel have to have the same level of additives to get top-tier certified. So it is just a myth and old phony marketing that premium contains more additives. I don't think the fuel is inherently "worse" or dirtier but rather that your engines are changing timing to be as close to knock as possible. For this system to make sense, there must be a few knocks that the sensors detect once in ahwile as it shifts the timing to see what it can get away with. You don't tell your car I put in premium this tank; it automatically detect. So the suboptimal combustion could be creating the extra color in your oil. End result maybe the same to you, it's a "dirtier" result; but my opinion is really the lower-grade fuel itself could've run just as cleanly if the engine management treated it fully differently rather then asking the management system to find the timing point.
The fuel needs to have a minimum amount of cleaners to keep the fuel injectors clean. Thats what is required. But the company can add more if they wish.
 
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Assuming what OP said is true, the only logical reason would be that higher octane fuel burns cleaner (more completely) even in an engine designed for 87. Cleaner more complete burn = less carbon blow by contamination in the oil. I believe that a lot of websites claim this as a myth.
 
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Originally Posted By: cookieman214
Originally Posted By: raytseng
The Top-tier FAQ states that all grades of fuel have to have the same level of additives to get top-tier certified. So it is just a myth and old phony marketing that premium contains more additives.
Not according to Shell. http://www.shell.us/products-services/shell-for-motorists/fuels/vpower/faq.html Q. Since the Shell Nitrogen Enriched Gasolines clean up engine gunk in all three grades, what makes Shell V-Power different? A. Shell V-Power is our most technically advanced gasoline. It contains our highest octane gasoline as well as the highest concentration of our patented Shell Nitrogen Enriched Cleaning System. With five times the cleaning agents required by federal standards, Shell V-Power cleans up performance-robbing gunk even faster than Shell Regular grade gasoline in both conventional and modern, direct injection engines.
Years ago I read the same thing on Chevron's website about the Techron content in their gas.
 
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Ok, so how is any of this gas cleaning the oil? That gas that cleans "gunk" is meant to clean "gunk" on the intake valves, not the oil or any place the oil reaches. And if it does, your engine is burning oil. At which point your piston crowns will be pretty dirty. I could possibly see the retarded/advanced timing angle though......maybe
 
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No lie, I just filled up with Shell V power when previously, I was using Exxon super and I am getting a lot more pep and believe the above info about using 5 times what was required. In this gas, the Exxon is top tier and previously, I got a spike in perf but I must have gotten even more detergents with the Shell V power with up to 5 times the minimum. Figures, EM is hype in gas just like their M1 is with UOA yielding higher NA or sodium content. ruh roh, not good. plus it burns oil, M1 is overhyped, imo. purely empirical and not anecdotal or knee jerk reaction at all.
 
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How would more detergents contribute to more "pep"? I detect placebo. I could buy the theory that if the higher octane fuel burned cleaner, it probably would not contaminate oil as much, but without blotter tests done for comparison, we're speculating on possible placebo effects here.
 
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Originally Posted By: HKPolice
Assuming what OP said is true, the only logical reason would be that higher octane fuel burns cleaner (more completely) even in an engine designed for 87. Cleaner more complete burn = less carbon blow by contamination in the oil. I believe that a lot of websites claim this as a myth.
The more efficiently something burns, the less byproducts of combustion are emitted. This isn't a myth, its science. OP I cant vouch for the color of the oil when drained, but I can vouch for how my vehicles run on different brands and/or grades of fuel! Cheapo bunker fuel = rough idle and decreased mileage. Top tier fuel (like Shell), smoother idle increase in gas mileage.
 
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Pretty sure 93 octane burns cleaner than 87. I always run 93 in my turbo engines, and whenever I have the heads off they are a clean tan color, not the black like most engines I've had apart that I know ran on 87. For those who are apparently not understanding, the fuel isn't cleaning the oil, it's just not contaminating the oil as much. Think of it as the difference between used gas engine oil and used diesel engine oil. The diesel oil always comes out black enough to stain your hands because diesel burns dirtier and therefore contaminates the oil more.
 
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Perhaps slightly more soot in the blowby gasses with regular than with premium? Or put another way, additives in the high octane fuel enabling better, cleaner burning? Less fuel enrichment due to less fuel-enrichment chamber cooling efforts required with the hihg octane fuel contributing to the above?
 
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Originally Posted By: ForceFedMopar
The diesel oil always comes out black enough to stain your hands because diesel burns dirtier and therefore contaminates the oil more.
That's not entirely true. The primary reason diesel oil gets jet black is because of the EGR, which ensures constant presence of very sooty exhaust gasses in all cycle strokes instead of just the exhaust stroke. My causin removed the egr on his Ford diesel van and says the used oil looks as clean as in gasoline engine now.
 
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Originally Posted By: jrustles
Perhaps slightly more soot in the blowby gasses with regular than with premium? Or put another way, additives in the high octane fuel enabling better, cleaner burning? Less fuel enrichment due to less fuel-enrichment chamber cooling efforts required with the hihg octane fuel contributing to the above?
Bingo! OP said he has no oil consumption issues so it must be cleaner blow-by as a result of higher detergent content of premium Shell gas vs regular. Dirty blow-by will settle in with the oil when engine is not running.
 
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There are 2 variables though. The higher fuel additive is only one; there is the obvious one that the octane and base fuel is also different. Why have people jumped to the conclusion that the behavior is just because of the different fuel additives dosage? Why is the difference in octane as a variable completely ignored? To have confidence to make the above statement, he needs to runs regular and also add fuel additive that matches or even exceed the premium concentration, then you can say it's because of additives and everything else was equal.
 
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