couple of GT questions

ok guys, I have had my 2000 GT for about 3 months now and I love it. I am changing the oil, filter, and fuel filter tomorrow. One of my problems is that when i am accelerating to 45 the car stays at around 40mph and feels like it wont shift down, it feels like I am tapping my foot on the accelerator and the speedometer bounces back and forth alittle. Its enough to notice, but not be a hazard. I am able force shift it by taking my foot off the gas and putting it back on, this fixes it for the trip but it seems to do it pretty regularly on my way to college. Also, I have heard that it is better to use an oil filter for a blazer as opposed to the one specifically for grand prix, has anyone tried this?thanks guys, matt

Sounds like what mine does when I put cheep gas in the tank. You may have a bad spark plug or coil. Try better gas I run the low octain but from Sunoco.

How many miles do you have on it? Any modifications? Could be a spark problem, could be a fuel delivery problem and could be a tranny problem.

I usually put 89 in it but about once a month I spring for 91 octane. I am going to college so I dont have the money to mod her out. Its got 64,000 miles on it. I was going to put new spark plugs and wires in it next. Thinking about NGK platinums but I have heard that AC Delco works best in it. Also was thinking about Accel 8mm wires.

Demon, what you mean by the 40mph thing is like the car has rough shifting? Because if that is the case then could be your transaxle that might fail soon, that is how my GP prior encarnation started to make me miserable until once I was cruising at 65mph and all of the sudden it went to neutral and I blew the engine cause it rev hard for a long while(music to damn loud and small +incline to feel something was wrong soon enough). IF you mean is just hesitation then could be spark related.

When I speed up to around 40 mph he car will plateau out and jolt. the tach bounces and the car shakes. I am 90% sure it a transmission thing. I can take my foot off the gas then put it back on and the car will shift, but its almost like it is struggling to shift.

Well if that is the case then you might need to havce the tranny serviced.

I usually put 89 in it but about once a month I spring for 91 octane. I am going to college so I dont have the money to mod her out. Its got 64,000 miles on it. I was going to put new spark plugs and wires in it next. Thinking about NGK platinums but I have heard that AC Delco works best in it. Also was thinking about Accel 8mm wires.

FYI, you are wasting your money on that 89 octane (and the 91). The 3800 SII N/A engine is designed & tuned for 87 octane (or as GMMerlin put it, the crappiest low octane fuel you can find). Running 89 octane in it really has no benefit..other than making your wallet lighter.

Stay away from platinum plugs with this motor. Go with autolites or AC Delcos. As far as the wires..well IMHO wires are wires unless you're heavily modded. Hell, my 90 LE has 132k on it, and it's still running great on the 13 year old stock wires. :naughty:

Rom, from what year onwards the GTP can use 89 octane?

FYI, you are wasting your money on that 89 octane (and the 91). The 3800 SII N/A engine is designed & tuned for 87 octane (or as GMMerlin put it, the crappiest low octane fuel you can find). Running 89 octane in it really has no benefit..other than making your wallet lighter.

Stay away from platinum plugs with this motor. Go with autolites or AC Delcos. As far as the wires..well IMHO wires are wires unless you're heavily modded. Hell, my 90 LE has 132k on it, and it's still running great on the 13 year old stock wires. :naughty:


Is this true?? I can notice a difference with my acceleration whenever I use 91, and when I use 87 I can notice the lack acceleration.

Rom, from what year onwards the GTP can use 89 octane?


96 and previous GTPs can run 89 octane gas (the ones without a supercharger)
all GTs can run 89 Octane gas
97 and newer GTPs have to use 91 or better Octane gas

Okay well I have a 99 gt with the basic mods, intake, shift kit, 180 stat and all the free mods listed on zzp. I do notice a difference when I was 87.

I've always put 91 or 93 octane in my 98 gt. Higher octane still gives me better acceration doesn't it?

To my humble knowledge higher octane fuel basically is fuel that requires a little higher temperatures to spark. That is why supercharged or turbo vehicles usually requires higher octane fuels(if what I said is correct), they tend to run a little hotter and to prevent premature ignition higher octane fuel is required. IF you use a cooler thermostat then the car might not require higher octante fuel. If anyone outthere can verify this is correct please do so.

If you have a GT and it isn't supercharged, it doesn't matter what octane you have. Octane is simply a meassure of gasoline ignition. You either have enough octane, or you don't. More doesn't help. The supercharged engines need the higher end octatne, but the GTs don't need it.

Octane is important up until the point that you have reached the minimum octane rating that you need. After that, you don't get any benefit. If you don't hear knocking, you probably have enough. But with newer cars, the computers can sense if you don't have enough and they will compensate for it so that you don't get knocking. This is when you lose horsepower. 87 octane is enough for the Grand Prix GTs however.

The only reason that you may want to use the higher priced gasolines is because of the additives that the oil companies put into them. Many oil companies put better additives in their higher octane gasolines. They make it "cleaner" than the other octanes. It is the same type of thing that gas additives that you buy at AutoZone do.

That is true about the octane and the additives for most cars, however it does make a difference with the supercharged cars. Not because of heat, it is due to the extra compression from the supercharger. These cars must have the higher octane. do not use less than rated on any car that obviously displays what the octane rating should be. using higher than rated is not really good or bad. A good rule is use the minimum rated fuel for day-to-day driving and use the "best" in one tankful a month for the detergents. This helps with injectors and passageways. From extensive research, Use Amoco Ultimate or Silver for the good stuff. Gasoline is gasoline for all gases except these. These are the only patented gasoline on the market.