Fuel for a VF SV6 S1

[Ryan83]

Hi,

I bought my VF SV6 late 2019, I’ve always put 91 unleaded in my car.

Could I be doing damage by doing so, if so should I be using 95 or 98?

Thanks

 

[Forg]

The manual will say what it can run on.
If I’m honest I can’t recall, but I’m moderately sure they’re happy on 91.
Maybe try a few tanks in a row of 95, see if it feels any more peppy? After checking the manual (or someone who knows for sure answers). Our V6 VS felt like you were carrying a boot full of boulders to run on 91 after we were used to it on 95 …

 

[07GTS]

usually inside of the fuel door will have a sticker saying its recommended fuel

 

[gossie]

91 is fine and what they were built to run on.
5-30 oil in the sump changed often.

 

[Ryan83]

usually inside of the fuel door will have a sticker saying its recommended fuel

The fuel door doesn’t say, I’ll have to check the manual.

 

[lmoengnr]

The fuel door doesn’t say, I’ll have to check the manual.

If it has that sticker, its basically approved to run on any petrol/ethanol based fuel.

 

[Skylarking]

IIRC, the Series I SV6 has the LFX engine as built by Holden?

And the GM LFX is rated for Regular Unleaded and is also E85 capable. But note that regular unleaded in the USA has an octane rating of 87 though this is the (MON+RON)/2 which IIRC is close to our 91 RON.

Being that the VF Series I SV6 review also specified 91 RON, I am sure you’d be safe with that fuel, or E85 or any blend of ethanol with 91/95/98 RON…

Modern vehicles have knock sensors and can thus cope with a wide range of fuels with various obtain ratings (within their tune limits). More knock detected = more the timing is retarded to protect the engine = less max HP produced. So 98 will in theory get the best performance but it won’t be the best cost based performance

 

[RevNev]

91 is fine and what they were built to run on.
5-30 oil in the sump changed often.

The LFX engine wasn't built to run on 91, the compression ratio is way too high. Knock sensors pulling ignition timing out enables them to run on 91 but not at maximum efficiency. There're a few spots where the knock sensors pull timing out on 98 and that's on the cusp of sufficient octane.

 

[Skylarking]

The LFX engine wasn't built to run on 91, the compression ratio is way too high. Knock sensors pulling ignition timing out enables them to run on 91 but not at maximum efficiency. There're a few spots where the knock sensors pull timing out on 98 and that's on the cusp of sufficient octane.

Yet with the LFX as used in the USofA, GM specs regular petrol which is 87 ((RON+MON)/2)

Using 91 may not be the most efficient performance wise but it’s not hugely less in the amount of kms per tank verses 98 so it’s somewhat cheaper to run with… and according to GM it supposedly causes no long term damage to the engine doing so

 

[RevNev]

Yet with the LFX as used in the USofA, GM specs regular petrol which is 87 ((RON+MON)/2)

Using 91 may not be the most efficient performance wise but it’s not hugely less in the amount of kms per tank verses 98 so it’s somewhat cheaper to run with… and according to GM it supposedly causes no long term damage to the engine doing so

The correct fuel for any engine is determined by the detonation resistance at the ignition advance producing maximum torque. GM are relying on knock sensors to reduce ignition timing and prevent detonation using a lower octane fuel. The LFX engine at a compression ratio of 11.5:1 would need at least 100 octane fuel as they detonate on 98 between 4750 and 5300 rpm. Manufacturer fuel recommendations take cost into account like extended oil change intervals for the perception of being cheaper to run and maintain, but it's not necessarily ideal for the engine.