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Discussion Starter · #1 ·
I have a 93 LS 2.5 DOHC V6. its a 5 speed. Does it require premium gasoline since its kind of the high end model?

(just got the car so im wondering)

thanks!!
 

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With my previous LS's I ran regular unleaded (87 octane) and it ran fine for daily driving. If you have the owners manual it will tell you what grade of fuel to put in. But IIRC it says that regular is fine.
 

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Bit of advice...you should never run low octane fuel in multi-valve engines....premium high octane should always be used for engine protection, performance & economy!
Hope this helps.
 

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Discussion Starter · #4 ·
With my previous LS's I ran regular unleaded (87 octane) and it ran fine for daily driving. If you have the owners manual it will tell you what grade of fuel to put in. But IIRC it says that regular is fine.
The car didnt come with the owners manual, so thats why i'm wondering. Will 87 Octane cause the engine to knock? i think cars made after 1990 wont but I'm not sure
 

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Bit of advice...you should never run low octane fuel in multi-valve engines....premium high octane should always be used for engine protection, performance & economy!
Hope this helps.

Hogwash. Please don't post misinformation.
Plenty of 4 valve per cylinder engines run perfectly fine on 87 or even 85 octane..

Keep this out of the new Member forums.


A stock KLDE runs fine on 87 octane in the USA.
A KLZE.. that's another story.
 

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Hogwash. Please don't post misinformation.
Plenty of 4 valve per cylinder engines run perfectly fine on 87 or even 85 octane..

Keep this out of the new Member forums.


A stock KLDE runs fine on 87 octane in the USA.
A KLZE.. that's another story.
I dunno, from what I've heard it's always best to use the higher octane fuel. I remember reading this same argument on probetalk, so I decided to test it out and I did get better mileage running the higher octane.
 

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I dunno, from what I've heard it's always best to use the higher octane fuel. I remember reading this same argument on probetalk, so I decided to test it out and I did get better mileage running the higher octane.

I think the V6 has a knock sensor - if so it might advance the timing to take advantage of the premium fuel. If the timing advances, then it could very well get better mpg and should make more power.

I'm on my first tank (got the car EMPTY - I was surprised it made it to the gas station lol) and I started with regular, 'cause I'm cheap, lol - I'm really hot rodding it and so far, no pinging that I can detect (tho' I'm not so good at the high sounds anymore lol :D) - my next tank will be a full batch of Chevron Premium. My mpg won't really reflect normal driving -like I said, it's new to me, and I'm having fun :D but eventually I'll do a few tanks of each, in a row, and determine if there is any improvement w/premium.

As for a general rule, for MOST cars, I'd say premium does NOT help, just costs more money to no benifit. It's less explosive, harder to detonate, than regular - in winter, it tends to misfire more in extreme cold start up. In normal driving, unless the motor conditions lead to detonation/knock and require premium, it shouldn't help or improve running at all. Premium requirement is mostly a function of compression ratio, not 4 valve combustion chamber design. Lots of high performance, 4 valve engines have high compression I'm sure, and do require high octane - so I can see it being associated with 4 valve engines a lot. My 1979 Honda CB750F had 4 valve heads, and a 9500 rpm redline, but did run on regular.

For my background, I was a Ford tech from 92 to 97. I had training on the Probe/Mazda, but didn't work on even one - mostly because in Alaska, it's 90% SUV/Trucks. I might still have a Ford CD with some Probe manuals in it, I should check :D
 
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