Premium fuel is recommended, is regular okay though?

[SteveTheTrafficCone]

I'll be moving somewhere with much more expensive fuel within a year and I daily drive a 1995 SHO MTX. It recommends premium, but I don't know what the premium fuel octane rating was 23 years ago. Could I get away with regular fuel?

 

[luigisho]

You may get arguments for both. I have used premium since the beginning, others have used regular and state that the adaptive programming can handle it. I don't know of any solid tested evidence to say that is or is not correct in regard to optimum operating efficiency. So you can try it out and see how it goes.

 

[zoomlater]

Here is a write up from awhile back

http://web.archive.org/web/20050414...le=article&mode=thread&order=0&thold=0&sid=51

 

[rubydist]

an excellent article by Gary M that matches my experience - use regular in these motors.

 

[Toolman]

87-89 is fine for stock.

 

[KyngofPop]

87-89 is fine for stock.

I’m sure that Car and Driver article is still floating around where they did EXTENSIVE testing on the S.H.O. and they found that even at the limits in stock form 87 is fine. They even went to Ford and Yamaha engineers and the explanation to the “Premium recommended” thing will shock and wow ya...


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[RonPorter]

I’m sure that Car and Driver article is still floating around where they did EXTENSIVE testing on the S.H.O. and they found that even at the limits in stock form 87 is fine. They even went to Ford and Yamaha engineers and the explanation to the “Premium recommended” thing will shock and wow ya...


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Yep. I've got copies of the 89 Pat Bedard C&D article. Any stock Gen 1-3 SHO runs just fine on 87 octane 99% of the time.

 

[zoomlater]

That was the article I was originally looking for until I found Gary M. write up

 

[PaulTAutoX]

That was the article I was originally looking for until I found Gary M. write up

Gary certainly had the experience with higher performance SHO motors. That said, the octane requirements for all motors change with age and amount of carbon and other deposits. The change is generally in the direction of needing more knock tolerance / slower ignition so that deposits will not result in pre-ignition. Deposits also take up room in the combustion chamber and result in higher effective compression ratio, which are another factor in wanting higher octane.
When do these become factors? Class repeat after me, "It depends." How soon on a specific motor that has not been disassembled to see? "I don't know." So if you don't hit on it hard as in track days/drag racing hard, and don't have modifications to boost output, well those guys are probably right and you could at least cut back to 89 at lower elevations. In CA you can't get over 91 octane at the average non-racing-gas pump. In Santa Fe, 7100', you can't even get over 90. Mine has some mods, I will probably stay with the 91 it has grown up with. If I didn't have those, I'd cut back to the 89 at most, unless I heard knocking on a regular (no pun intended) basis.

 

[itwonder]

The problem I have with Patrick Bedard's article is it mis-characterizes and over-simplifies detonation. Asserting that legitimate Ford power plant engineers would state that detonation is a non-issue because they don't hear pinging is absurd and further detracts from the article's credibility. Detonation may occur and not be heard at all. Offering a completely gratuitous assertion, I've often wondered if there is some weird connection between the mysterious crank cancer and use of regular fuel. That's pure unsubstantiated speculation on my part. However, for what it's worth, and it may not be worth much at all, we have run the recommended premium fuel since the SHO was new, and (knocking on wood), no crank cancer...so far. You, of course, can do what you want; I won't argue, and I respect your opinions.

 

[KyngofPop]

The problem I have with Patrick Bedard's article is it mis-characterizes and over-simplifies detonation. Asserting that legitimate Ford power plant engineers would state that detonation is a non-issue because they don't hear pinging is absurd and further detracts from the article's credibility. Detonation may occur and not be heard at all. Offering a completely gratuitous assertion, I've often wondered if there is some weird connection between the mysterious crank cancer and use of regular fuel. That's pure unsubstantiated speculation on my part. However, for what it's worth, and it may not be worth much at all, we have run the recommended premium fuel since the SHO was new, and (knocking on wood), no crank cancer...so far. You, of course, can do what you want; I won't argue, and I respect your opinions.

I’ve run all 8 of my SHO’s on regular and not one caught crank cancer...


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[RonPorter]

There's nothing at all wrong with Bedard's article and having an actual powertrain engineer explain it tells you all that you need to know. The "detonation that no one hears" is 100% urban myth. Any pinging, and especially detonation, can most definitely be heard. And detonation isn't even close to being an issue. Not enough octane produces occasional pinging, which is what the article referenced. And there have been other tech articles about other engines written since then that say the same thing.

Every EFI engine built since the mid 80s can run for their entire lives on 87 octane. Ford's EcoBoost, as well as all other, turbo engines are the same way.

Reread the article and understand what it says. The wisdom from 1989 is still relevant today. These ain't your grandpa's carb and points engines.

 

[RonPorter]

I hope that the crank cancer - octane comment was totally tongue in cheek, because that is the most ridiculous thing I've heard in years!

And BTW, stock V6 and V8 SHOs run better on 87, especially real gas with no alky. And the higher compression V8 SHOs like it better. The first four stock Gen 3 SHOs that ran in the 14s, mine being the first, all did it on 87.

 

[KyngofPop]

There's nothing at all wrong with Bedard's article and having an actual powertrain engineer explain it tells you all that you need to know. The "detonation that no one hears" is 100% urban myth. Any pinging, and especially detonation, can most definitely be heard. And detonation isn't even close to being an issue. Not enough octane produces occasional pinging, which is what the article referenced. And there have been other tech articles about other engines written since then that say the same thing.

Every EFI engine built since the mid 80s can run for their entire lives on 87 octane. Ford's EcoBoost, as well as all other, turbo engines are the same way.

Reread the article and understand what it says. The wisdom from 1989 is still relevant today. These ain't your grandpa's carb and points engines.

My Twin-Turbo V8 BMW 550 Xi that “requires” premium runs just fine on 87....along with the hundreds of others that do.


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[SHOdded]

They made hundreds of those things?

 

[KyngofPop]

They made hundreds of those things?

And they were all shit, mine the worst one


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[SHOdded]

Did you drive the 850 series? Looked cool as all getout.

 

[KyngofPop]

I’m not going anywhere NEAR any Bmw again no matter how cool it looks. I’m over it lol


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[SHOdded]