Questions and Answers
Gasoline Grades
Q. The auto in question is a 2001 VW Passat GLX with the 2.8L V-6, 190HP, Tiptronic, front wheel drive. The owner's manual specifies 91 octane premium which is generally not readily available. Regular is usually 87 octane, mid-premium is 89 and premium is 93.
Alternating fillups between full and mid premium would be close enough, but like most modern engines it is equipped with knock sensor(s) to prevent harmful detonation.
The engine is quite powerful and smooth running and I'm hard pressed to feel the difference between the power output using the specified octane and just using regular. I realize the engine computer will compensate for a lower octane and produce less power, but are there any lasting harmful effects from using regular on a continuing basis?
I only use name brand gasolines that have full detergent and additive packages in their regular grades as they have in the premium lines and purchase from service stations that sell a large volume of gas so their deliveries are regular and the gas is "fresh". If it's of any consequence, 75% of my driving is at highway speed, I average 15,000 miles a year and rarely keep my vehicles beyond 3-4 years.
A. You could put in five gallons of 93 and five gallons of 89 and that would average out to 91. I'm not sure if it actually works out that way but it sounds good.
Ideally you should use the 91 octane if you can get it. If not the 89 will suffice without any damage to the engine. If you want a little extra performance you can go with the 93 but I don't believe the little extra you get justifies the added cost. In my area we have the reverse problem, 91 is common and 93 is difficult to find
Additional Information provided courtesy of ALLDATA
