Gasoline question

[Sal Lubrano]

Where I live the only octane available is 87, 89 or 93. My 1990 240dl volvo requires 91 octane. My question is should I use 89 and chance some detoniation and have the ecm retard the timing or use the 93 but then the motor will not be able to burn it correctly and carbon will build up. What would you do???

 

[tom h]

... or use the 93 but then the motor will not be able to burn it correctly and carbon will build up. What would you do???

Octane has no effect on this, AFAIK.

If your car is a 1990, there is probably all sorts of crud built up in combustion chambers, irregardless of what octane you've been using.

I would suggest 2 treatments of GM Top Engine Cleaner, with say 50 miles of freeway/highway driving in between ... even if it's a week apart.

Then try 89 and see if engine "pings", else move up to the 93 octane.

 

[Quiky One]

Where I live the only octane available is 87, 89 or 93. My 1990 240dl volvo requires 91 octane. My question is should I use 89 and chance some detoniation and have the ecm retard the timing or use the 93 but then the motor will not be able to burn it correctly and carbon will build up. What would you do???

I'll trade you our 91 for your 93 haha...All we have around here is 91 and good luck running 15 psi without alky. alky rules...ok sorry to hijack

Jason

 

[ijames]

Run the 93 or if you want to save a little put in 2 gallons of 87 for every 4 gallons of 93 - that will net you close enough to 91 octane. Around here 87 is $2.19 and 93 is $2.49 (this morning, anyway, at my local Exxon), so if a fillup is 12 gallons total for you start with 4 gallons of 87 then top off with at least 8 gallons of 93 and you will spend $28.68 vs. $29.88. Only a $1 a tank but if you drive lots and lots of miles it might add up enough to make it worth the hassle.

 

[zeus87gn]

Run the 93 and forget about it. The motor will burn it just fine.
It will run better longer, self clean the combustion chambers and valve seats over a few tanks, keep the cat converter and fuel injectors clean, and your fuel mileage will be better than with the 87.

Premium is worth every penny to me.