What type of gas should I be putting in my '99 spyder gs?

of course 93 if the budget permits....but 87 or corn hootch would work as well~

hey there's a carguru named spyder99...you shoud PM him or her~

The highest octane you can get. 93 is what runs best.

What if I just filled half a tank with 87 and now I want to fill the rest up with 93?

It will run on 87 but it suppose to run on 93. If you run 87 you could feel a lack of performance. With the compression ratio of that engine anything less than 93 octane will ignite before the piston makes it all the way to the top of its compression stroke. It will not really hurt the engine to run 87 but you will have a lose of gas mileage and performance. I advice to run only 93.

only the best will do for dandyoun~ personally would fill with donut oil if it'd get me there...~

Lol. Have this same discussion with my wife every couple of months. She will be asking why her GS is acting sluggish. When I ask what gas she putting in she turns red faced and says "the cheap $hit". After about two tanks of the 93 her car is no longer sluggish. But I know it won't be long and she will be asking the same question and I will give the same answer.

with a diesel motor you can run off donut oil or veggie oil...it requires a pre- heater to liquify the oil prior to injection...but the exhaust smells like french fries (there was a guy in Berkeley who had a ratty jeep that would go around to all the donut shops and fryer grease places to run his jeep off the oil)~....while I worked at Urban Ore, general store (which got their inventory from salvagers posted AT the dump...everything they sold was flawed)~...reselling crap...literally to the tune of many millions of dollars~

can run a little lower octane with ethanol than regular gas but 91 and better should be fine