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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Thu Oct 18, 2018 7:23 am Post subject: Re: 90 vs 91 Octane Gasoline |
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I can tell you that the rubber line used in marine outboards starts to look cracked at the ends at the 10 year mark, and they aren't exposed to much heat unlike the hoses above our air-cooled engines.
It's been 8 years since I did mine and I'm about to tackle the project again. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50348
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Posted: Thu Oct 18, 2018 9:43 am Post subject: Re: 90 vs 91 Octane Gasoline |
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WildIdea wrote: |
So, VW folks, are storage and harsh environments a consideration? |
I would say yes they are considerations. Heat is going to boil the alcohol out while raising the temp will speed up chemical degradation of the fuel. Boat owners really have to pay through the nose if they choose to use ethanol laced fuel as boats tend to sit for such long periods and may be either stored out in the sun under a tarp/boat cover or in uninsulated sheds that bake in the summer sun. Many a boat owner has taken his boat out of storage, fired it up run up and down the lake a bit and shut the engine off to fish, swim, or other. When he fires the engine back up to head homeward to the marina he revs the motor and get a big bang as a piston slams into a valve that has become stuck in its guide because of the crud from degradated fuel building up on the valve stems. |
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Thu Oct 18, 2018 11:30 am Post subject: Re: 90 vs 91 Octane Gasoline |
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WildIdea wrote: |
So, VW folks, are storage and harsh environments a consideration? |
YES on any vehicle which is stored for a significant period of time non-ethanol gas is just plainly better, particularly if the gas tank goes through temperature swings.
As the gas heats and cools, it expands and contracts and draws outside air into the tank along with the humidity in the air. The humidity combines aggressively with the ethanol in the fuel, raising the moisture level in the gas. Up to a certain point this is a good thing, in fact they used to sell alcohol as a "moisture absorber" additive. However eventually it reaches a saturation point where, on a cold night, the ethanol/water mixture phase separates and settles to the bottom of the tank. This water/ethanol mix is highly corrosive to your tank, your fuel lines, and basically everything else, along with not burning in the engine.
Fuel additives like "Sta-Bil" help with gas oxidation and varnish, but do little to prevent phase separation despite the marketing hype.
It helps a lot to store the gas tank full. This way there is less air space for humid air. Or conversely, drain the tank and fuel lines so there is no gas at all.
But still, ethanol gas is best used fresh. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50348
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Posted: Thu Oct 18, 2018 11:43 am Post subject: Re: 90 vs 91 Octane Gasoline |
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WhirledTraveller wrote: |
But still, ethanol gas is best used fresh. |
I have come to believe that fresh equals no more than a month old. Even then it may show some signs of aging, clogging carb jets and injector tips. Just had to dump some FI cleaner into my '83 1/2 to perk the engine up a bit even though the gas in that rig seldom exceeds a week old.
Some areas of the country have better gas than others as there are variation in the fuel supply to account for climate. |
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udidwht Samba Member
Joined: March 06, 2005 Posts: 3779 Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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Posted: Thu Oct 18, 2018 7:35 pm Post subject: Re: 90 vs 91 Octane Gasoline |
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In my RV (94 Fleetwood Southwind Storm) P30 454 TBI I always prior to putting into storage (around late Sept~Oct) put (1) large 80 gallon treatment of Sta-Bil into the fuel tank (60 gal.) then fill it full. Then turn on the generator for ~ 20mins with half load. Drive to storage and park. Cover RV.
Come ~7 months later she fires up perfectly including the generator(Onan MIcroquiet 4K) _________________ 1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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Amskeptic Samba Member
Joined: October 18, 2002 Posts: 8568 Location: All Across The Country
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Posted: Thu Oct 18, 2018 7:45 pm Post subject: Re: 90 vs 91 Octane Gasoline |
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telford dorr wrote: |
Another side note: as far as I know, the oil companies only sell two types of gas: 87 and 91 octane. |
Except when they are selling 85.5 above 4,000 feet . . .
Colin _________________ www.itinerant-air-cooled.com |
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Whaanga Samba Member
Joined: May 07, 2016 Posts: 627 Location: Rochester, NY
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Posted: Fri Oct 19, 2018 8:03 pm Post subject: Re: 90 vs 91 Octane Gasoline |
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As a follow up - I filled up today with the 90 octane non-ethanal gas. I looked for any kind of technical information and as you can see in the first photo, no details are given. In the second photo, they do provided R + M/2 - not really sure what I'm getting here - except having my wallet drained ($3.50 per gallon). Of course this is NY so we pay HIGH gas taxes (along with everything else).
_________________ Late 1973 Bay w/a transplanted 914 Engine |
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Sun Oct 21, 2018 6:54 am Post subject: Re: 90 vs 91 Octane Gasoline |
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R + M / 2 is the standard in the USA and is the same as AKI (anti knock index).
90 is perfectly fine for most any non-race engine.
I wish I could get that for my small engines. Here in Mass non ethanol is nowhere to be found. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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richparker Samba Member
Joined: November 24, 2011 Posts: 6982 Location: Durango, CO
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Mon Oct 22, 2018 2:42 am Post subject: Re: 90 vs 91 Octane Gasoline |
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91 RON is approximately 87 R+M/2
Basically normal pump gas. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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udidwht Samba Member
Joined: March 06, 2005 Posts: 3779 Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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Posted: Mon Oct 22, 2018 3:02 am Post subject: Re: 90 vs 91 Octane Gasoline |
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The VW manuals had slews of discrepancies over the years.
91 octane regular
_________________ 1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22665 Location: NYC/Upstate/ROW
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Posted: Mon Oct 22, 2018 3:53 am Post subject: Re: 90 vs 91 Octane Gasoline |
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That 91 octane was the EU version, which is 87 in the US. _________________ .ssS! |
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chittychittybangbang Samba Member
Joined: August 12, 2006 Posts: 194 Location: portland, or
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Posted: Mon Oct 22, 2018 4:38 am Post subject: Re: 90 vs 91 Octane Gasoline |
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I saw 85 octane somewhere in the Midwest about 8 years ago. My stock 1600 did not like it one bit!
_________________ If your into busses youve got issues and you likely don´t know it yet. - El_Güero
The question of whether the resulting usage is "correct" or "incorrect" depends on one's notion of correctness. |
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udidwht Samba Member
Joined: March 06, 2005 Posts: 3779 Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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Posted: Mon Oct 22, 2018 4:40 am Post subject: Re: 90 vs 91 Octane Gasoline |
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Abscate wrote: |
That 91 octane was the EU version, which is 87 in the US. |
And yet they didn't print that. Which was my point. _________________ 1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50348
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Posted: Mon Oct 22, 2018 5:45 am Post subject: Re: 90 vs 91 Octane Gasoline |
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I ran sub regular "Gulftane" in all my rigs for years. It was one of the first gasolines to go low lead and then no lead which meant that lead deposits and lead sludge became a thing of the past early on for me. People shied away from it because it was the cheapest gas out there and they bought the BS about the valve seats wearing if there was not lead in the gas. |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22665 Location: NYC/Upstate/ROW
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Posted: Mon Oct 22, 2018 9:18 am Post subject: Re: 90 vs 91 Octane Gasoline |
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udidwht wrote: |
Abscate wrote: |
That 91 octane was the EU version, which is 87 in the US. |
And yet they didn't print that. Which was my point. |
Yeah , you would think they print the manual for the market in which the vehicle was sold. I guess fuel engineers were out to lunch on manual day _________________ .ssS! |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50348
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Posted: Mon Oct 22, 2018 11:54 am Post subject: Re: 90 vs 91 Octane Gasoline |
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WhirledTraveller wrote: |
91 RON is approximately 87 R+M/2
Basically normal pump gas. |
Abscate wrote: |
udidwht wrote: |
Abscate wrote: |
That 91 octane was the EU version, which is 87 in the US. |
And yet they didn't print that. Which was my point. |
Yeah , you would think they print the manual for the market in which the vehicle was sold. I guess fuel engineers were out to lunch on manual day |
Having two different systems that were presented to the public and then making a third just to try to appease both sides is super ridiculous. Kind of like the "maximum cold inflation pressure" written on the side of the tires, which is actually the minimum acceptable cold inflation pressure if you are running the tires at their full rated load while driving at high speeds. Supposedly they don't want to confuse the public by giving them sensible information. |
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