87 octane -vs- 93 octane

Chuck77 · Posted: Sun Oct 18, 2009 9:32 pm Post subject: 87 octane -vs- 93 octane

I was hung over last Monday morning and needed to fill Vangina up on my way to work. I mistakenly grabbed the Super unleaded handle rather than the regular and didn't realize it until I was nearly full. I left a little mad that I paid a bit more, but in all reality I'm sure I could come up with the difference in loose change inside my van.

I'm sure that there will be naysayers, but I think that my van is actually running better. I feel that the acceleration is a bit more brisk, and that my exhaust note is a little raspier. Mileage has not been too different either. Is there something to this or is this wishful thinking?

PS correct idle set, fuel to air ratio within spec, injectors in good shape, and a brand new fuel filter.
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1988 Vanagon GL 7 passenger, 15" Mercedes 8 hole alloys with Nokian Hakka's (SOLD)

Wildthings · Samba Member Joined: March 13, 2005 Posts: 51950

Why don't you have your wife randomly fuel your van for you the next several times and not tell you what fuel she puts in each time , but record it somewhere out of sight. Then once each tankful is nearly gone you can write down your thoughts on how the engine is running. After 5 to 10 tankfuls you can compare your notes with her records and see what has worked and what has not.

blakeck2 · Posted: Sun Oct 18, 2009 10:25 pm Post subject:

I too have done that and like the 93 better, I have been told and read you cant notice a difference but I do Very Happy

Crankey · Samba Member Joined: July 11, 2004 Posts: 2672

blakeck2 · Posted: Sun Oct 18, 2009 11:35 pm Post subject:

morymob · Posted: Mon Oct 19, 2009 5:37 am Post subject:

Lucky that around this area u can still buy reg without the ethanol added, thats what i use and automatic 2+ mpg on all vehicles. Otherwise when i travel i get what is cheapest,all seem the same.

thewump · Posted: Mon Oct 19, 2009 7:11 am Post subject:

I found the opposite. I used Premium when I bought the van and found that it "hunted" at idle so lowered through Super now to Standard and find it optimal.

For me the "hunting" was evidence that the mix was too rich. I'm more of a carb guy, but in the Vanagons, the system is supposed to compensate I guess - but Premium in a CA van in CO seemed beyond it's range.

K
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87 Weekender

McVanagon · Posted: Mon Oct 19, 2009 7:55 am Post subject:

Wildthings · Samba Member Joined: March 13, 2005 Posts: 51950

Chuck77 · Posted: Mon Oct 19, 2009 11:46 pm Post subject:

I wasn't that hung over to use diesel. Plus my wife hates driving it.
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1988 Vanagon GL 7 passenger, 15" Mercedes 8 hole alloys with Nokian Hakka's (SOLD)

AndyBees · Posted: Tue Oct 20, 2009 5:26 am Post subject: 87 vs 93

The 93 basically provides benefits to the engine with lots of carbon build-up in the combustion chamber which can and does cause pre-ignition.

Pre-ignition is more noticable on hot days with engine under load.
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'84 Vanagon Tin-top, ALH TDI, two trips to Alaska, 2014 & 16. 1989 Tin-top unmolested.
1983 Air-cool, 225k miles, 180k miles mine, seven trips to Alaska from 1986 thru 2003. 1975 Bay hopeful.

thewump · Posted: Tue Oct 20, 2009 8:45 am Post subject:

elpedro · Posted: Tue Oct 20, 2009 9:28 am Post subject:

wenholzm · Samba Member Joined: February 14, 2010 Posts: 140

I have made two trips to the USA from Mexico and have found that the Van runs better with the 87 in Mexico than the regular in the USA. When up north I use at least 91 octane and get good results. I assume this is the result of the non polluting agents, I guess our gas down here is of the 1985 vintage that my Westy likes.
Also I sealed the tank with some gunk I got here and it worked OK in Mexico, but on my trip to the USA the gasoline ate this stuff and plugged my filter numerous times making my trip horrible. I have just put on the reseal kit from Van Cafe and so far it looks good, the test will be on my trip north next May 2013, plan to go up to Montana. Cannot wait!
All the best

MSwart · Posted: Thu Sep 13, 2012 11:00 pm Post subject:

Always use the highest octane value available. Wink

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'89 2.1

thisguyfel · Posted: Fri Sep 28, 2012 4:55 pm Post subject:

reluctantartist · Posted: Fri Sep 28, 2012 6:22 pm Post subject:

Pure gas is the way to go if you can find it close to you. I have noticed a ~1.5 mpg difference in city driving and more on the highway. The closest station is about a gallon of gas round trip distance away so it isn't worth getting for me. But if I wasn't needing mine everyday that would be the only fuel I would use.
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1982 Westy, 1974 412 Variant... Yes, Aircooled's are great! Oh and I do have modern computer controlled vehicles too, but I just don't care about them.

IdahoDoug · Posted: Fri Sep 28, 2012 6:55 pm Post subject:

The higher octane fuels don't burn more fully, or more faster, or provide more power so you would not notice any difference at all. Was once part of a study evaluating people's ability to discern the difference in powertrain outputs, etc - people could not really detect even sizable differences.

DougM
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

Wildthings · Samba Member Joined: March 13, 2005 Posts: 51950

Owning several older carbureted rigs, I have been forced to switch to ethanol free over the last year. They just will not hot start on regular with any ease anymore. My bus engine will 9 times out of 10 fire on the first cylinder that ticks over on ethanol free high test, but will take 15 or more seconds of cranking at WOT to hot start on regular. My wife forgot to fill my Thing with high test last time and she has twice had to just sit and wait an hour for the engine to cool so that she can get a restart. My seldom used Dodge which had 8-9 year old fuel in the tanks started last year and ran will little effort, but after running a couple of tanks of regular through it and then letting it sit for a month the fuel gelled in the carb.

I used to revel in running low octane fuels like Gulftane and Sunoco 170 in bygone days while friends felt they needed to run the higher grades in similar models, but today I have been forced to move to high test on my carbureted rigs. As for FI rigs I can't say yes or no at this point.

IdahoDoug · Posted: Fri Sep 28, 2012 10:05 pm Post subject:

Yeah, the ethanol regular gasoline is a total clusterf#ck from the word go. You probably already know what happened, but the ethanol can strip settled stuff from normal gasoline accumulated over the years and make it mobile (liquid) all at once. Likely the Dodge's situation. I have absolutely nothing good to say about these E10/15 fuels. They are a total waste of taxpayer money and they are damaging the things we use them in. The program is now considered an agricultural subsidy and will never go away as a result. I'd much rather simply cut farmers a check, personally.

You can find a station in your area selling "real" gasoline by googling for the website that has these locations by zip code. Can't recall it. We have one, fortunately.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader


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