Hello
Just a question about the best fuel to use for a 4.2 series 2, do you recommend using a fuel additive?
Thanks for the info.
Aaron

 

If it was me, I'd use the 97 (or higher) octane stuff you can get, like BP Ultimate or Tesco Momentum, although it's a bit expensive.

These engines were OK for lead-free from the 70s due to Californian regulations. However, you can easily use the 95 octane and put a bit of Castrol Valvemaster in, as that has an octane booster in it as well as the lead substitute

 

As an Ex-Pat living in California, I cringe when I see 87 octane here.

 

Don't forget that North America has a completely different octane rating systems compared to the rest of the world.

87 here is called 91 there.
93 here is called 97 there.

All is not lost.

 

My car as a DOHC ran just fine on CA's 87. A shot of Techron from time to time.

And now, powered by an LT1 does just as well on 87.

Unless the engine has to have the higher octanes, usually because of higher compressons or chamber design, it is a waste of money.

My 94 Jeep Grand Cherokee with it's old AMC six "modernized" with FI does fine on the 87 as well.

Now, way back, my hot Landcruiser demanded the highest as well as my flat head with skimmed Edelbrocks atop!!

And, my turbo'd sorta Corsa Corvair like the $ stuff best!!

Carl