My daughter just bought a 2008 Passat 2.02
and needs to know if she can run 87 oct in
it rather than 89 ? Or, do the specs on VW engines require the 89 to avoid ping or
knock ? I thought that she could probably
get away with the 87 as this is not one of
the upper end higher performance engines.
Read the owner’s manual. It will tell you whether 89 octane is required or recommended. If it is recommended, then she can try 87 octane. If required, use only 89. I’d use 89 octane anyway - it’s what the VW engineer’s require or suggest. They do it because the car is set up to run best on 89 octane. There will be some loss of power and possibly fuel economy with 87 octane. I’d pony up the 10 cents per gallon for 89 octane.
The manual should say Recommends or REQUIRES premium.
If it says requires, it means you car can’t always adjust to regular fuel and could be damaged by using regular.
If you choose to use regular when it recommends premium, remember that using regular is likely to reduce mileage and will reduce power.