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[DobaMark]

I need a picture of the back cover of the 1985-1989 owner's manual where it states the octane requirements for the cars.


I believe it says premium recommended for the 318-2 engines, regular for the 318-4 engines.


Thanks!

[Dippy.org]

[Patrick]

While I no longer have the book, My 5th (318-2) said Premium recommended on the both the dash and on a sticker on the fuel door.

[DobaMark]

Now all I need is the octane spec for the 318-4. I think it's regular.

[Mike]

my 1984 and 1989 5th Avenue ones say 91 recommended 87 acceptable.  Don't know if the Dodge/Plymouth manuals differ but it does talk about 318-4 HO engine inside the book along with the same ratings so it's probably all the same.
The 1979 book says to use 87 octane which  it says is the same as 91 research octane rating.

[lsm360]

Mark, would you like an Owners Manual for an '88 Gran Fury? I have one you can have if you like. If you want it, PM your address.


I do remember my '85 civi 318-2 having decal reading "Premium Unleaded Recommended". My '89 AHB with 4 barrel does not have that decal.

[270SE]

'85 is when they went to the new pistons and upped the CR on 318s. For a 318-4, it's still low enough that regular is fine. My '85 2bbl truck motor did not like cheap gas in high altitude. The '84-down 318s are fine on cheap gas.

[DobaMark]

Mark, would you like an Owners Manual for an '88 Gran Fury? I have one you can have if you like. If you want it, PM your address.


I do remember my '85 civi 318-2 having decal reading "Premium Unleaded Recommended". My '89 AHB with 4 barrel does not have that decal.

Thanks, I am still digging through my old stuff. I think I have one hidden away somewhere.

I was told the timing was so advanced on the M body 4 bbl cop engines that they needed premium.
You've confirmed that isn't the case.

[lsm360]

I was still running premium in mine with stock 318-4 because I always set timing advanced as much as possible without pinging for a little extra umph.

[MoparDan]

Here you go