Recommended Octane

Look in the owners manual, don't go any lower then what it says.

If it does say you need 91, you could use 87 in a pinch if premium is not availible, but engines designed for 91 will have to operate at a reduced mode with 87, and engine damage could result if something like a knock sensor failed.

First check the owner's manual or sticker on the cover over the gas cap. What does it say to use.

Using something higher is a waste of money. The car will not run better, cleaner faster or get better mileage. Going down to 87 if it calls for 91, will mean it will loose a little power and will loose some mileage. It might also harm the engine. My guess is it will not harm the engine, you will not likely feel the difference in power and you will about break even on the total cost of gas.

The point is why buy a performance car, pay extra dollars when you buy it and then cheap out using regular so you don't get the benefits you already paid for trying to save a few pennies, which you might not save after all due to reduced mileage.

Read your owners manual, that's what it for. If you look on the gas door it should have a label which states premium.

From section 3.2 of the '03 Passat manual (I assume the '04 says the same thing):

The fuel recommended for your vehicle is unleaded premium grade gasoline with a minimum octane rating of 91 AKI (CLC) or 95 RON (ROZ).

Followed shortly by:

Do not use any fuel with octane ratings lower than 87 AKI or 91 RON otherwise expensive engine damage will occur.

-- Mike Smith

Can you actually get 91 where you live? I've never seen it, myself. 'Round here (Long Island NY) it's either 89 or 92-93. Back in the days when Sunoco had five different grades, you could get 90, but not 91.

-- Mike Smith