Hey guys. We just put a Spectre Cold Air intake on my truck and I have been using 89 octane gas for a few weeks now. I just put 91 and Lucas fuel injector cleaner in last night. I think I may be getting less mileage now, but that is probably because just after we put the intake in, I had to install my roof cargo box to take everything home from college next weekend after finals are over. It was fighting 25 mph headwinds in addition to the high speeds on the NYS Thruway (I-87 and I-90 in NY State), so that could be why I was getting 16 mpg instead of 18-19 and used 11 gallons instead of the usual 9 gallons (according to the overhead console computer) over 180 miles of driving. Should I be using just plain 87 octane with a CAI for better mileage? Thanks for any advice.

Also I hate to ask something unrelated, but how do I remove stickers/decals from windows? I can't wait until I can remove my parking pass (expires at the end of the semester anyway) and my college logo sticker from my back window I now have covered with painter's tape because I don't want my friends from home seeing it when my truck is home.

 

I'm not sure about your octane vs fuel mileage, but that box on top really does have an effect on aerodynamics.

Use a new razor like the ones inpections stations use to remove old inspection stickers. To remove the sticky residue, use something citrus based like Goof Off. It will wipe right off.

 

Your engine was designed to run on 87 octane. Now, deposits in the combustion chamber may create hot spots which may cause detonation. Running a higher octane fuel will reduce detonation a to a certain extent. Running too high of octane will serve to only lower your mileage. Every engine is different so you will need to do some comparisons to determine which octane gives you the lowest $/mile. You may want to repeat the tests with different fuel stations as well. I have a few in town that my Rainier just does not agree with.

 

Thanks.

As with the different gas stations, does that mean there could be water in the gas? I know of this one Sunoco station near my house last year that sold gas for 10 cents below what everyone else was selling it for and once while using that 87 octane gas, I shifted into reverse once on level ground and the engine stalled. No SES light, but a code for a MAF high voltage thing was in the computer. Cleared it. That was the only time that happened. Switched gas brands and never had any stalling and it always started faster than my mom's Lexus RX350. Someone I know who drives an 00 Silverado had the same problem with stalling with that same gas. Never went back to that station.

As with the deposits, should I be considering Seafoam just before I drive the 40 min to the shop to get my oil changed? I use Lucas Upper Cylinder Lubricant every few tanks and random like every 1000 miles.

 

Different stations definitely could have different quality control, but they also have different formulations of fuel. Different additives can affect mileage in different ways.