There was a time not long ago when some vehicles were designed to use premium (91+) and they could not be operated at 87 without some issues. That time is long past for almost all new mainstream vehicles. Part of the issue is the VW brand. VW was the last affordable brand automaker in America to switch to designing cars for regular (87) unleaded for the majority of its vehicles. Part of it is that performance car enthusiasts know (think) that by running a higher octane fuel the vehicle will adjust its settings (using the knock sensor) and a slight increase in power will result. Good for them. If your GTIâs fuel cover sticker says it can run on 87, then VW is confident it is not going to cause any problems. If you can detect a performance improvement, and you feel paying more for gas is worth it, go for it. Having driven the GTI, I think any added power is bringing coal to Newcastle. The thing is super-quick in real-world use. One of my favorite cars. More so now that it uses the cheapest liquid fuel in America instead of the most expensive. The Golf R still is tuned for Premium by the way. All other 2017 Golfs including the GTI can use 87. Except the one that runs on electrons.
Use 87 octane and save your money.
My Stihl string trimmer requires 91 octane for the 2 stroke.
Thatâs one for which Iâd definitely buy and use the REC 90 gasoline (No Ethanol). Warnings on the pumps say âOnly For Off Road Useâ, or something like that (It has no road tax included, illegal for highway use). Itâs sold in several stations near me.
Ethanol can really screw-up small engines, especially if left in the machine for too long (think seasonal equipment). REC 90 is considerably more expensive than unleaded, but for lawn equipment one generally doesnât buy very much. To me itâs worth it.
CSA
Run the octane the VW manual states. There also should be a sticker on the gas fill door. In my case, on my 2003 Beetle 2.0 it is premium 89 octane for U.S. Even in my new 2017 Golf Sportwagen 4Motion it states 87 octane. I alternate 89 and 87 because of the carbon that is generated burning 87 octane in VW engines. Be warned, if you always run 87 octane in any 2005 or newer VW, the EGR system will become plugged with oily carbon at around 150,000 miles. You will continually have issues with the Check Engine System alerting you to some issue. That rectification will require dis-assembly of the Intake and EGR Systems to painfully clean all passages with small wire brushes and Brake Cleaner. I had to do that on my 2 daughters 2005 Golf and 2006 Passat. They both ran 87 Octane till the 150,000 miles range, and then brought them to me to fix.
If you donât plan on keeping your VW for more than say 80,000 miles, then the computer will compensate for the octane by reducing or increasing power as the knock sensor indicates. Your mileage maybe some what lower. With my octane alternating, I am getting 29 mpg in town and 38 mpg on sustained highway miles with the 1.8 TSI 4Motion and the DSG Transmission. I do use the paddle shifters a lot rather than mashing the Go pedal as much.
Because most people donât read the manufacturerâs recommendations. They enter the conversation believing they already know the answer. Car salesmen arenât scientists. Or physicists. Or chemists. Or engineers. Or mechanics. Thatâs why theyâre car salesmen. In truth, they donât really know any more about what goes on under the hood than you do. Maybe even less. But the guys that wrote the ownersâ manual do. Theyâre technical writers who get their information directly from the specifications documents of the final design package.
Using higher octane fuel will provide no benefit** in an engine with ânormalâ (aka low) compression ratios. But high performance engines, such as the lovely little guy in our GTIs, are designed with high compression ratios and tight tolerances, so they require higher octane in order to get maximum performance. The manufacturer has designed the engine with a specific octane figure in mind, and thatâs whatâs printed in the ownerâs manual.
**One caveat, if an older engine is pinging that can often be addressed by running higher octane, but itâs a band-aid for real problems like carbon buildup or bad plugs.