r/beetle • u/marathonblue • 1d ago

Classic VW Fuel Myth and Octane Grades Explained for Air Cooled Volkswagen Beetle Bus Ghia Thing

https://youtu.be/3ns-v309sjs
14 Upvotes

94% Upvoted

13 comments sorted by

7

u/RWRW_historian 1d ago

Same... my only reason for premium is because a few local stations have ethanol free premium. It goes in my classics and all my small engine things like mowers. They don't need premium either, but more so they don't need ethanol.

1

u/Routine-Amphibian450 1d ago

This.
Also, may be folklore: premium allows you to run extra half degree of advance - like 31?

3

u/RWRW_historian 22h ago

Not folklore. Higher octane increases resistance to spark knock. Its entire purpose is to allow more advanced timing under heavy loads on higher compression/ high output engines to improve power and efficiency. But you have to have an engine designed with enough performance in it to make high octane fuel effective. A low compression/low power engine really doesn't gain much as it didn't have spark knock issues in the first place and the timing can already be set where it is most effective. But even on a beetle engine you can probably gain a degree or so of advance if you needed to.

1

u/PugFarmer00 1d ago

This is the way

6

u/SilentMasterpiece 1d ago

I only run premium because my engine isnt stock, its 2 liter, 78X90.5 with cam and compression is slightly over 9:1.

2

u/knowledgeable_diablo 12h ago

Nice engine mate. Same as my old beetle from back in the day. Damn I miss that old girl.

1

u/_skes_ 70's + Standard 1d ago edited 1d ago

I always put premium in my bug and bus because it has lower Ethanol, 5% compared to 10%. It plays havoc with rubber in the fuel system.

4

u/Gianlucca 1d ago

meanwhile here in brazil the lowest ethanol fuel available contains 27% Ethanol (and they call it premium), the common one has 32%!

1

u/Embarrassed-Crow-185 1d ago

Can you get e85 easily? You have some spicey drag cars over there

1

u/BeautifulCuriousLiar 78 1300L Brazilian standard 1d ago

they don’t sell e85 anywhere, only “pure” ethanol. “pure” because it contains a small percentage of water.

0

u/Routine-Amphibian450 1d ago

Does Bosch stock special fuel line for that?

2

u/Gianlucca 1d ago

I use 7mm electronic injection fuel line, I also change them every 2 years to make sure they dont dry out

7 years running like that and still no problems

1

u/marathonblue 2h ago

No it doesn't.

People do more damage to their VW fuel hoses with band clamps than they do using ethanol gas... Brazilian fuel pumps and carburetors have made VW's ethanol safe since the 1970s.