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DI vs Octane #4749411
05/06/18 03:09 PM
05/06/18 03:09 PM
Joined: Dec 2003
Posts: 9,805
Florida, Cape Coral
Eddie Offline OP
Eddie  Offline OP
Joined: Dec 2003
Posts: 9,805
Florida, Cape Coral
I have seen several posts where it has been mentioned that the use of 91+ octane instead of the required 87 will help with reducing intake valve contamination. I would like to see some data or even a reason why this is possible. Ed


CX5 Touring 2.5L :-)
Re: DI vs Octane [Re: Eddie] #4749412
05/06/18 03:12 PM
05/06/18 03:12 PM
Joined: May 2005
Posts: 10,282
ROCHESTER, NY
Char Baby Offline
Char Baby  Offline
Joined: May 2005
Posts: 10,282
ROCHESTER, NY
I don't see how higher octane would change this considering the DI sprays straight down into the cylinder where as he port injection sprays on/past the intake valves to keep'em clean


"Retired"
-----------------------------------

'80 Firebird FORMULA V8/4bbl-purchased "NEW"
'15 Nissan Altima 2.5 SV
'15 Honda Civic LX
Re: DI vs Octane [Re: Eddie] #4749422
05/06/18 03:24 PM
05/06/18 03:24 PM
Joined: May 2018
Posts: 888
Tri State Conservative
Zee09 Offline
Zee09  Offline
Joined: May 2018
Posts: 888
Tri State Conservative
I'd like to know if the combo of PI. And DI. Resolves the DI. Issues
or it it too early to tell? Very interesting topic.


"If I walked on water, they'd say I couldn't swim."
Re: DI vs Octane [Re: Eddie] #4749423
05/06/18 03:24 PM
05/06/18 03:24 PM
Joined: Mar 2017
Posts: 5,480
Soviet State of Washington
PimTac Online content
PimTac  Online Content
Joined: Mar 2017
Posts: 5,480
Soviet State of Washington
I donít see the effect on valve deposits either. You might be confusing this with some reports that higher octane reduces fuel dilution of the oil.


2017 Mazda CX-5 Grand Touring

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Re: DI vs Octane [Re: Eddie] #4749426
05/06/18 03:29 PM
05/06/18 03:29 PM
Joined: Apr 2008
Posts: 37,187
Ontario, Canada
OVERKILL Offline
OVERKILL  Offline
Joined: Apr 2008
Posts: 37,187
Ontario, Canada
I can't see it having any real effect on valve deposits. I've read on here that it leads to less fuel dilution in the oil, which I would expect the theory behind to be less enrichment for anti-knock required with higher octane fuel.


2018 RAM 1500 Big Horn EcoDiesel
2016 Grand Cherokee SRT
Re: DI vs Octane [Re: Eddie] #4749429
05/06/18 03:32 PM
05/06/18 03:32 PM
Joined: Oct 2015
Posts: 252
Washington
Dylan1303 Offline
Dylan1303  Offline
Joined: Oct 2015
Posts: 252
Washington
I thought premium had the most cleaning juice vs 87 at some stations. Shell comes to mind.


12 cruze rs 1.4t 6spd pp 5w30 tuned on 22psi
13 equinox 2.4 awd pp 5w30
Re: DI vs Octane [Re: PimTac] #4749435
05/06/18 03:35 PM
05/06/18 03:35 PM
Joined: Jul 2009
Posts: 432
Seattle
Superflop Offline
Superflop  Offline
Joined: Jul 2009
Posts: 432
Seattle
Originally Posted By: PimTac
I donít see the effect on valve deposits either. You might be confusing this with some reports that higher octane reduces fuel dilution of the oil.
which may reduce pcv vapors depositing on the valves.. dunno though.


2002 saab 9-5 2.3t wagon
2014 dodge grand caravan
Re: DI vs Octane [Re: Dylan1303] #4749437
05/06/18 03:37 PM
05/06/18 03:37 PM
Joined: Apr 2008
Posts: 37,187
Ontario, Canada
OVERKILL Offline
OVERKILL  Offline
Joined: Apr 2008
Posts: 37,187
Ontario, Canada
Originally Posted By: Dylan1303
I thought premium had the most cleaning juice vs 87 at some stations. Shell comes to mind.


It doesn't really matter. The requirements for Top Tier, which apply to all grades if the brand is wearing the banner, are quite high to begin with.


2018 RAM 1500 Big Horn EcoDiesel
2016 Grand Cherokee SRT
Re: DI vs Octane [Re: Dylan1303] #4749446
05/06/18 03:49 PM
05/06/18 03:49 PM
Joined: Jun 2012
Posts: 1,704
USA
oldhp Offline
oldhp  Offline
Joined: Jun 2012
Posts: 1,704
USA
Originally Posted By: Dylan1303
I thought premium had the most cleaning juice vs 87 at some stations. Shell comes to mind.


At one time Shell V-Power had five times more detergent than Shell's regular.



Re: DI vs Octane [Re: Eddie] #4749473
05/06/18 04:37 PM
05/06/18 04:37 PM
Joined: Apr 2017
Posts: 402
Mississippi
Speak2Mountain Offline
Speak2Mountain  Offline
Joined: Apr 2017
Posts: 402
Mississippi
I've read that higher octane may help w/fuel dilution in DI engines.

Re: DI vs Octane [Re: Eddie] #4749487
05/06/18 05:06 PM
05/06/18 05:06 PM
Joined: Sep 2010
Posts: 7,485
S California
OneEyeJack Offline
OneEyeJack  Offline
Joined: Sep 2010
Posts: 7,485
S California
The real problem is the vapors that get recycled thru the PCV and the lack of help from the additives in the gasoline that don't get to the valves, anymore.

This might be a good time to reconsider a catch can to trap much of the contaminants.

https://www.youtube.com/results?search_query=catch+can

Re: DI vs Octane [Re: OVERKILL] #4749516
05/06/18 05:49 PM
05/06/18 05:49 PM
Joined: Sep 2006
Posts: 1,603
California
oldmaninsc Offline
oldmaninsc  Offline
Joined: Sep 2006
Posts: 1,603
California
Originally Posted By: OVERKILL
I can't see it having any real effect on valve deposits. I've read on here that it leads to less fuel dilution in the oil, which I would expect the theory behind to be less enrichment for anti-knock required with higher octane fuel.


I've mentioned this (less fuel dilution) after reading about it on another forum and after observing my own engine. Though I have heard people say about premium gasoline possibly reducing valve deposits, I agree I don't see how or why it could. I haven't seen any proof, just people saying what they thought. On a forum for my Impala, many believe running synthetic oil and changing it at 5K (or less) will help with the deposits and in the case of the 3.6 engine protect against timing chain problems. Not sure I agree with either but I have no proof either way!

In my area, premium fuel is usually 20 - 30 cents a gallon more, so it's not a big deal to fill up with premium (17 gallon tank). One guy on the Impala forum who uses the tuning software states there are different tables for premium fuel and I have seen a difference monitoring the fuel trims and the knock retard via Torque Pro.

Last edited by oldmaninsc; 05/06/18 05:52 PM.

2017 Chevrolet Traverse
2013 Chevrolet Impala LT
2005 Toyota Camry LE
2004 Mercury Grand Marquis LS, 1998 Ford F-150 XLT


Re: DI vs Octane [Re: oldhp] #4749527
05/06/18 06:03 PM
05/06/18 06:03 PM
Joined: Sep 2006
Posts: 1,603
California
oldmaninsc Offline
oldmaninsc  Offline
Joined: Sep 2006
Posts: 1,603
California
Originally Posted By: oldhp
Originally Posted By: Dylan1303
I thought premium had the most cleaning juice vs 87 at some stations. Shell comes to mind.


At one time Shell V-Power had five times more detergent than Shell's regular.


On their current web page, they state that: "Shell V-Power NiTRO+ contains the highest concentration of the Shell Nitrogen Enriched Cleaning System and cleans up faster than Shell regular."

https://www.shell.us/motorist/shell-fuel...oline-faqs.html

Last edited by oldmaninsc; 05/06/18 06:03 PM.

2017 Chevrolet Traverse
2013 Chevrolet Impala LT
2005 Toyota Camry LE
2004 Mercury Grand Marquis LS, 1998 Ford F-150 XLT


Re: DI vs Octane [Re: Eddie] #4749530
05/06/18 06:06 PM
05/06/18 06:06 PM
Joined: Dec 2003
Posts: 9,805
Florida, Cape Coral
Eddie Offline OP
Eddie  Offline OP
Joined: Dec 2003
Posts: 9,805
Florida, Cape Coral
As I thought. No reason to suspect that higher octane could reduce intake valve deposits as some have said. Ed


CX5 Touring 2.5L :-)
Re: DI vs Octane [Re: Eddie] #4749542
05/06/18 06:30 PM
05/06/18 06:30 PM
Joined: Jul 2004
Posts: 905
Indiana (IN)
shanneba Offline
shanneba  Offline
Joined: Jul 2004
Posts: 905
Indiana (IN)
87 octane gas may be less refined and have more impurities than 91.

https://www.sunocoracefuels.com/tech-article/octane-stability-high-octane-vs-low-octane-fuels

"87 octane fuels tend to be less refined and contain more unstable hydrocarbons.
As the months pass during storage these unstable components react to form gums, varnishes and lower octane hydrocarbons.
...
Even in proper storage 87 octane gas can start to degrade in 3 months, 93 octane fuel should last closer to 9 months before degradation is noticeable.
Keep in mind that 93 octane fuels are still susceptible to octane loss and vapor pressure decreases due to butane evaporation."


2003 BMW 330Ci
2013 HD Sportster XL1200C
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