You only need minimum 87 octane on your S13 240sx. For a great deal of information on 240sx's go to www.240sx.org especially the FAQ section.
Premium 91 Octane is recommended by Nissan.
" regular " unleaded , 87 octane
You can find that info in the owners manual.
Yes, the Nissan Altima only requires that you use Regular fuel. Premium iix not necessary and will provide no benefit whatsoever. Now, if you are referring to E-85 fuel that is totally different from 85 octane. You cannot and should not burn E-85 in your Altima.
regular unleaded 87 octane
According to the 2008 Lincoln Navigator Owner Guide : " regular " unleaded , 87 octane
If you check your owners manual it will tell you what gas you should used on your vehicle. For most part most vehicle are issue a 87 octane or above. Only high performance vehicles used 93 octane and above. You can used any gas you prefer too. The higher the octane the better the car will run. That's just my two cents.
87 octane should be sufficient
91 or 93
If you have the regular cobalt you need to use 87 octane gas and if it is the ss with the supercharged engine you use high test.
The owners manual says that higher octane is preferred for best engine performance, but it also says that 87 octane can be used without damage to the engine. I've been using a mixure of 87 and 89 octane and do not hear any engine-knock or pinging. The gas mileage probably would be better if 91 octane was used, but I haven't run a test on that aspect yet.
150 octane Avgas (no longer used) 100LL Avgas 98 octane premium leaded (no longer used) 95 octane unleaded 82 octane regular (no longer used) 80 octane Avgas (no longer used)