Has anyone tried running anything other than premium fuel in their Seville\Eldorado? I had a 95 Eldorado and currently have a 96 Seville. When I've tried anything other than premium fuel, I've noticed a significant decrease in MPG. I generally get about 17.5 with premium and barely get over 16 when using anything less.

I've also tried using lower octane fuel and tried compensating with "octane booster". Don't ask why... I was just curious. :helpless: Anyway, from what I've read, octane booster generally provides no real increase in octane or performance. It's probably just a marketing thing...

I'm also curious about about air filters. K&N doesn't make a filter for 96 Sevilles, but I was curious about Fram's new Air Hog. However, I cannot seem to locate a reseller online that has a filter for a 96 Seville. Actually, I can't even find a price... :confused: I bought a K&N filter for my 86 corvette and didn't notice any difference at all. :canttalk: However, my co-workers seem to think they're pretty great. At the very least, I like the idea of non-disposible parts.

Last thing.... Is there any real difference between OEM spark plugs and performance sparg plugs? In other words, if I changed OEM plugs with high end plugs, would I notice any difference in HP or MPG?

As you can see, I'm on a never ending quest to improve MPG in my Caddy.

the best thing you can do is have new plugs/wires and o2 sensors. Do those and youll be happy.....


USE ONLY OEM PLUGS, you wont get any better mileage with other plugs.... Factory plugs are the only way to go, end of story...

Dont get a K/N filter, the drop ins are worthless, and the cone filters are even more worthless. If you want more noise, more dirt in your engine, and ultimately less engine life, by all means!! :)

For the $50 youd spend on a K/n, you could have 10 years worth of paper filters. Get AC delco paper filter and replace them every year.....


You have to think to yourself, if the factory didnt put it in and it made that much difference, why wouldnt the engineers put it in to start with???

Yea, but the factory didn't put dual four barrels on every 440 that came off the dodge line, and it would have made PERFECT sense to do that, eh? Just my two cents, I'm bored and thought I'd be a li'l obnoxious.:bouncy: