The owners manual and gas filler door on my 2007 3.0 V6 Montereo assembled in Bogotß, Colombia states 91 octane or higher is required. There are only two grades here and premium is more than a dollar higher than regular at about four dollars a gallon. The dealer salesgirl no doubt to make the sale, told us it?s fine to use regular and it?s true I haven?t heard any pinging going up our long mountain road while using that grade. I?m guessing the kaka will hit the fan when it?s time to take it in for the annual emissions test. Can anyone think of any other reason why this nearly twenty year old engine design (G12 is it?) would require premium gas?

It's all about the compression ratio. The higher the compression the more anti-knock you need in the fuel. The engine management system senses the knock before you can hear it and retards the timing to prevent knock, ping or detonation.

I don't know what the long term effects are. Does it run better with premium?

If it has a knock sensor, theoretically, you should be able to use the lower octane gas. You will notice a performance difference, but emmissions should be unaffected. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Ok that explains it. I?ve used only regular up to now but maybe I better at least alternate at fill ups. (There goes my pension!)

I just use 87 Oct in my cars. I expect your's does not have a knock sensor as with our earlier versions in our Montis and trucks. My pickup does not complain about the low octane fuels. The DOHC in my car surges a bit when using high power below 3000 rpm but once it comes on cam it pulls strong and smooth.

At 2007 without a knock sensor?

I wouldn't be surprised. The South American trucks are different - may come from a different factory. I believe some of the late models in Venezuela look similar to Japan spec bodies, but have leaf springs - so it wouldn't surprise me if the South American 3.0L engines still are Gen1 spec with a distributor.

Frank

Yes, this is why they still have the 2nd gen chassis and 12 valve engines. The goal in many countries is simple reliability. Keep in mind VW still produces air cooled cars, They are in countries that primarily use alcohol for fuel the aircooled engines work fine.