quote:

Originally posted by Wishbone:
I have 2 Nissans with the VQ 3.5L engine. The Maxima requires 91 octane but the Muarno is fine to run 87 octane. I guess it's in the tune of each car.

I've always wondered about that. I may be mistaken but I'm under the impression that the Land Cruiser can take regular but the LX570 requires premium. Not sure why if true.

Interesting article.

http://newsroom.aaa.com/wp-con...h-Report-FINAL-2.pdf

Six different cars that recommend premium, run on premium and regular on a dyno. MPG and HP effect.

The link is to a 68 page report of their findings.

Interesting reading.

Vanwall--I recognize that name.

Wikipedia: Vanwall racing

That's an awesome and incredibly thorough article -- thanks for posting that.

Cliff Notes after 69 pages:

"The following recommendations are specific to vehicles labeled premium recommended. There
is not a clear case where premium gasoline is beneficial from a cost perspective. In most cases,
the extra cost of premium over regular does not result in a positive return on investment (lower
cost to drive a given distance). However, there are instances – and they vary widely by vehicle
type and model – where the use of premium gasoline can be marginally beneficial."

--------------------------------

quote:

Originally posted by sjtill:
Vanwall--I recognize that name.

Wikipedia: Vanwall racing

Stirling Moss fan here.

quote:

Originally posted by Expert308:
I get no knocking or other issues when I run 89 in it.

Just be aware not all detonation that can occur falls in the audible spectrum. In other words you could experience detonation, but not hear it.

For the first three years, I used premium as specified for my Lexus gs350. But after that, I switched to the middle grade. At that point, I figure the incremental wear or damage from the lower grade isn't going to be significant over the normal wear and tear.

quote:

Originally posted by jigray3:

quote:

Originally posted by Expert308:
I get no knocking or other issues when I run 89 in it.

Just be aware not all detonation that can occur falls in the audible spectrum. In other words you could experience detonation, but not hear it.

I did not know that. Is there another way to detect it, other than hooking it up to a diagnostic computer?

The Mazda CX-9 is rated 227 HP with 87 octane, 250 HP with 93 octane.

If I recall correctly the factory numbers on my 6.0L G8 were 355 on 87 and 361 on premium. This is also my first modestly faster 10.4 to 1 compression engine.

Though it can accept all 3 grades (NOT E85) I can tell you from over 100,000 miles of driving, the feel of each grade is different. I run 89 or premium because of the response out of the pedal. The car feels mundane with 87. I have about a million miles with a dozen other cars and only 1 other car felt different with better gas, but it IMO it does happen. Perhaps the compression ratio?? Motorheads please feel free to clarify.

If it’s turbocharged and it says run 91/92, I run premium. If the mfr. of said car says use premium, I use premium. If the extra $5 per tank is that big of a deal I don’t think I’d be buying a new car.