I have a '99 XK8 convertible (X100). I read this morning the Biden administration is mandating 15% Ethanol in all US fuel this Summer. No confirmation yet, and I don't care about the policy implications.

I've read conflicting information on how big a problem this is for a pre-2001 car.

Does anyone have any definitive information on potential issues with this model and high ethanol fuels?

My thought is that if it turns up a problem, I might blend 5 gal per tank of 100 Octane E0 to bring down the overall ethanol ratio. Any opinions?

 

We have E10 in the uK and they say the rubber in all the XKs is ok for ethanol.
The UK government checker says...

Jaguar

E10 petrol is cleared for use in all Jaguar vehicles with petrol engines starting from model year 1992. Older models should continue to use E5.

 

Thanks, that's reassuring, to a point. Unfortunately we're looking at E15 this Summer.

From the reading I've done, there's apparently a 'blend wall' between E10 and E15 where older vehicles can have problems. I'm not sure how much of this is cruft and how much represents a real issue- certainly a lot of it is cruft.

The thing that caught my eye was that one of the potential issues was with the engine running hotter. I live in Arizona, and my XK8 is already dyspeptic over the 110+ degree Summer weather. It's my daily driver so I want to take care of it.

 

If you look in the drivers handbook that comes with the car, Jaguar says that fuel with up to 10% ethanol can be used, so it sounds like 15% is out of spec, but the the car is designed to withstand ethanol fuels.

I think I would try the E15 and see how the car performs.

 

Your only worry will be using a tank of E-15 (or E-10 for that matter) before it gets old enough to separate into the different components. That usually takes 3 months or more.

Aside from that, the car will automatically adjust the F /A ratio to achieve the best performance.




Z

 

Sorry, ethanol is crap and should only be used in race cars. It was political garbage from the beginning and it shouldn't be.
Off my soapbox, thank you. TM

 

My understanding is it will be an option not a mix for all fuel. But its as ckear as everthing else so its likely to flip flop. But, I get pure gas non ethanol 93 from time to time. You can always use that if it's not optional. Seems like there would be a huge class action suit if it were mandatory 15% and people's engines got damaged. But again that could be another way to move people toward electric cars. Regardless I'll not use 15% in my XKR I'll fully switch to pure gas.

 

Do fuel stabilizers help keep ethanol in suspension?

 

their advertising says they do, but I am reluctant to trust them very far.

If one must store the car I would fill the gas tank just before storage and use a reputable stabilizer like Sta-Bil.


Z

 

you are misunderstanding what happened. E15 was approved for sale year round instead of winter only. You only find this stuff being sold as 88 octane

E10 (usually 7-8) is not going away anytime soon

 

Oh, now I remember hearing that.

Yeah, to echo xalty and clarify, it's not that they're mandating E15 but rather that there's normally a seasonal prohibition on it, and they're dropping the prohibition just this time.

In other words (other, other words I guess) if you're going to get E15 then you were probably already getting it all winter. Normally they would have shifted away from it for the summer for environmental reasons, but this time they're permitting (not requiring) gas companies to keep it in the mix for the next few months in response to the gas shortage.