I have a 91 Z28 TPI with in around 132k miles, completely stock. What octane gas should I be using? I have been using 93 or 91 since I had the car, which has been a year now. I have a few people telling me I'm wasting money on the Ultra/Premium gas and should just use the 87 oct. 87 to me is like putting sludge in your tank. I figured the car is 22 years old, has 132k miles on it and is a 305 V8 with the TPI system. So it needs the best it can get. So am I right using 91-93 or 94 octane gas or just use the 87 octane.

 

Well i use 87 in my Koup and truck as they call for it, 93 in the HD it calls 91 or higher. As for the TA I run Sheetz 93 in it as it's old and I would rather not risk pinging and since I don't drive it everyday the cost is not much differant.

 

I use 87 and run knock free. The only reason to run anything higher than 87 is to prevent knock.

 

your fine with 87, specially being stock. If you had a built motor, it would be different. Every once and awhile toss a bottle of octane booster in like on every 3 tanks.
Seafoam works wonders also!

 

They are saying that because you are wasting your money. Absolutely no reason to run anything other than lower grade on a stock motor. Start reading up on motors and you will know why.

 

Count the pumps, and then count how many holes are in the ground.

 

I run 87 in my 87 and have NO issues.

 

If you are completely stock, the 305 engine can be run on 87 octane.

 

87 is a pretty base engine. 87 will be perfectly adequate unless you have an issue with the engine. Here in colorado, they HIGHEST you can get is 89 octane! You don't really need premium anywhere, anytime for a base 3rd gen engine.

 

My owners manual from 91 says to run 89 in TPI V8's