4Star Petrol in Griff

[Hoover.]

Been running my Pre-Cat Griff 4.3 on super unleaded, mainly BP Ultimate.....

Have been wondering about 4 Star stuff though, as the garage down the road sells it.....

Does this go off like the unleaded petrol......

& what if any benifit would i see for running on 4 Star.....

[Platinum]

Hoover. said:

Been running my Pre-Cat Griff 4.3 on super unleaded, mainly BP Ultimate..... Have been wondering about 4 Star stuff though, as the garage down the road sells it..... Does this go off like the unleaded petrol...... & what if any benifit would i see for running on 4 Star.....

They still sell 4star

I thought it was 'banned'...?

[zumbruk]

Platinum said:

Hoover. said: Been running my Pre-Cat Griff 4.3 on super unleaded, mainly BP Ultimate..... Have been wondering about 4 Star stuff though, as the garage down the road sells it..... Does this go off like the unleaded petrol...... & what if any benifit would i see for running on 4 Star..... They still sell 4star I thought it was 'banned'...?

Nope. You can still buy it in a few, very restricted places;

www.bayford.co.uk/leaded_petrol.asp

[RUSSELLM]

A couple of stations around my way have it, but I'm sure they call it a "4* replacement"

Must have additives.

[tvr450]

I would guess that it might kill the cat, if you have one fitted?

[zippee]

tvr450 said:

I would guess that it might kill the cat, if you have one fitted?

Hoover. said:

Been running my Pre-Cat Griff 4.3

[Fire99]

From my understanding, most '4 Star' fuel on sale is LRP. (Lead Replacement Petrol to those not in the know)

From my days of running a very early M5 i remember LRP being flippin horrible stuff.

Im pretty much certain any decent super-unleaded (optimax or BP Ultimate etc) will be miles better for your engine than any 4* replacement.

Anyone else had any experiences?

cheers,

Nick

[griffsmith]

I've heard I think on previous threads here that is the best thing to run a precat on! better performance blar blar..This could just be 'bar room banta' mind, I've not tried it myself yet...

[leorest]

My understanding is as follows

Petrol Fuels available

Unleaded. The norm now. It’s not LRP without the lead it’s chemically different

Super unleaded. As above but with additives packages to improve octane

Opti-Ulti-Maxi… Standard Unleaded with additives package engineered to improve octane and cleaning.

4*. The real stuff with lead in. Probably the unleaded as above with Tetraethyl Lead added

LRP, (Lead Replacement Petrol). Unleaded with additives package to boost octane and reduce valve seat recession.

As I understand it all the fuels start off with the same base stock and have additives to modify their characteristics for different applications. So I would guess that the 4* or LRP would “go off” just the same as any other unless they have anti-going off additives!

Running 4* in a Griff wont have any performance benefit over an unleaded with the same octane as your engine has hardened valve seats which are designed for unleaded.

It is only worth using fuel of an octane rating similar to that which the engine is set up to run on (timing). Higher octane and it won’t realise the extra power available and lower will pink like bu99ery. This is an over simplification but you gets the point.
If the ECU has a knock sensor then it will adjust advance according to what it can get away with whilst not knocking, so it will adapt to the actual octane whether it’s a mixture of different pump fuels or it’s a degraded/gone off fuel that’s been laying in the tank for a while.

Best advice is to drive the car often so the fuel doesn’t get the chance to go off Run the tank low for lay-ups then top it up with fresh stuff for use, and use an Opti-Ulti-Maxi which has cleaning additives or alternatively use regular and your own choice of cleaner.
Hope that helps
Leo

[Andrew Noakes]

leorest said:

If the ECU has a knock sensor then it will adjust advance according to what it can get away with whilst not knocking, so it will adapt to the actual octane

The leaded petrol (the proper stuff, not LRP) available now tends to be higher than the 97 octane of super unleaded, so if the ECU can adjust the timing to take advantage there will be a small benefit. But leaded petrol is not easily available so personally I wouldn't bother using it if the engine can cope with unleaded - I'd use Optimax or equivalent.

[Fire99]

Andrew Noakes said:

leorest said: If the ECU has a knock sensor then it will adjust advance according to what it can get away with whilst not knocking, so it will adapt to the actual octane The leaded petrol (the proper stuff, not LRP) available now tends to be higher than the 97 octane of super unleaded, so if the ECU can adjust the timing to take advantage there will be a small benefit. But leaded petrol is not easily available so personally I wouldn't bother using it if the engine can cope with unleaded - I'd use Optimax or equivalent.

Tesco do a 99 Octane super Unleaded. If you really want very high octane levels that may be worth a try. Though i didn't notice any benefit over Optimax.

From my understanding there are differences in fuel quality between some of the suppliers so i wouldnt treat the Octane level as the only issue to consider.

My Chim always seems to run best on Optimax or BP Ultimate.

[Hoover.]

I asked the question as the petrol station down the road stocks 4 Star leaded petrol.

Last night I was chatting with the manager who confirmed that it was the real leaded stuff and not LRP. He says he sells quiet a bit of the stuff, which I guess is why he has it on two pumps out of the 9.

Seeing as my car will run on the stuff, I'll give it whirl and report my findings back in a week or so.

[profstoff]

There's a good article in this month's Sprint which explains a lot of this stuff in easy to understand words. basically if you're not knocking, you won't get any improvement using a higher octane rating, Optimax and BP Ultimate aren't higher octane than Premium unleaded but have cleaning additives so any performance gain will come when the engine cleans up and if your car runs unleaded withoput probleme, the only effect of running leaded petrol is to screw up the environment.

[Andrew Noakes]

profstoff said:

if you're not knocking, you won't get any improvement using a higher octane rating, Optimax and BP Ultimate aren't higher octane than Premium unleaded

Need to be careful with the terminology here. Optimax et al are higher octane than Premium unleaded, because Premium unleaded is the 95 octane normal stuff.

You will get an improvement by using higher octane fuel if the engine management system can retune the timing to take advantage of it.

[Tyre Smoke]

Slightly off topic here, but my Cerb is currently running Sainsbury's SUL (Optimax was unavailable at the time) and the pops and bangs back through the de-catted and sports exhaust are definitely less. Any idea why? Surely one RON difference (97 Vs 98 alledgedly) won't make that much difference?

It's like someone has fitted bigger silencers on it!!

[V8Smith]

Tyre Smoke said:

Slightly off topic here, but my Cerb is currently running Sainsbury's SUL (Optimax was unavailable at the time) and the pops and bangs back through the de-catted and sports exhaust are definitely less. Any idea why? Surely one RON difference (97 Vs 98 alledgedly) won't make that much difference? It's like someone has fitted bigger silencers on it!!

You should try the new Tescos 99 RON its fantastic for pops and bangs too....? I know people have noticed the difference between this and Optimax, I havent, so maybe 1 RON does make a difference???

Mike