I'm hearing that some of it is no longer 99 octane like V-Power, but, even though marketed as Momentum, is now only 97 octane.
True?
Or more internet rubbish?

 

Not according to Tesco…… looks like internet rumors
https://www.tesco.com/help/pages/tes...co-momentum-99

 

Some Esso stations are showing both 99 and 97 on the same labels Bob Rawle said earlier in the year V Power was limiting power when he was mapping so he advised to use Momentum or Esso Supreme but not sure if that advice has changed recently.
Shell are still saying it is 99 on their website.

 

I read somewhere (probably Pistonheads) that Esso Supreme is supplied via Greenergy which is the same supplier as Tesco.

Make of that what you will....

People have tested various brands of E5 and found Ethanol content varies (as its "upto 5%" ethanol). Momentum has previously been tested as showing zero Ethanol. Hence the rumour it was the same as Esso Supreme (also zero).

BUT since September 2023 , Esso said Supreme is no longer Ethanol free. Which suggest that Greenergy is to supply both Tesco and Esso with Ethanol blends in its Momentum/Supreme fuels.

To me that means the fuel has changed to what it was last year (or will change soon). Particularly Supreme, but possibly also Momentum. As such the octanes could also change. Bear in mind legislation only requires it to meet 97ron at point if supply. Anything above that is not legally enforced.

No issue with Tesco Momentum myself. I just used Esso Supreme because it clearly stated it was zero Ethanol. Sadly that's no longer the case.

I'm finding all modern fuels, especially containing Ethanol a right pain in the ****; I'm going have to start doing DIY separating it as per the youtube vids then adding my own octane booster (OK on bikes and garden tools, not exactly practical on cars).

Every old car I get in at work thats stored over winter that comes in with a running/performance issue has to have the tank drained of fuel. Even a Volvo V70 (mint Gus Frink car).


Would be good to hear from mappers how they find varying levels of oxygenates in fuels affect the closed-loop fueling trims. Theory is more Ethanol/Oxygenates = more oxygen in exhaust = sensor reads leaner = richer fueling trim. Just wonder what the real life outcome is, especially with narrowband, semi-wide and wideband sensors.

 

Most of the 99 octane fuels have more ethanol in Devon, Cornwall and Scotland, possibly Tyneside, for some reason.

 

I've started buying that Miller's ethanol - effects additive for my classic. It has started and run fine when left garaged over the last two winters.

 

Momentum 99 , you can’t go wrong , some Tesco’s did not do momentum only a 97 octane , I always opt for momentum , option 2 is Esso 99 or shell 99 ££ , my jdm were fine on momentum pre being mapped 👍