Fuel additive XK

Living in Taxifornia we have no choice but to use gas with a high concentration of alcohol (ethanol); what do drivers use to combat the destructive action of this additive?

Ron, i use what we call E10 here in Aus for all my cars including the Jag, never had any problems with it, occasionally i’ll use a tank of non ethanol fuel as a flush fluid, i do have an article in my library on my website you might be interested to read, under the heading ‘Fuel Tech’ >>

what is the % of ethanol in your fuel?

Shock/horror Tom - what model Jaguar do you have, with what engine and its compression ratio. E10 sold in Australia is only usually available in base 91/92 Octane fuel, and is totally unsuitable for any XK engine with greater than 7:1 compression ratio. Most 1950s/60s XK engines in Australia are 8:1 cr (occasionally 9:1cr) which should not be run on 91/92 Octane fuel regardless of ethanol content or not.
Certainly in early 1950s there were 7:1 cr Mark VII and XK120 sold new in Australia, which will run OK on 91/92 Octane fuel without risk of pre-detonation and in extended/extreme cases damage to your engine.

Re the Ethanol content aspect, independent of the octane rating. Still not advised to use E10 in an XK Engine/SU carburetter fuel system for extended periods, albeit you will get away with it ‘for a while’
The ethanol does and will react with non-ferrous metals, especially brass, that you will find you have in your SU carburetters Fuel Bowl float and gauze filters, and indeed the seat part of the needle/seat… Ethanol can/will also react with certain plastics, not that that will be an issue in an SU fuel system being pre use-of-plastics. More modern cars, when the politics forced Ethanol fuels upon us (for dubious environmental benefit claims) had to redesign their entire fuel systems, fuel tank to carburetters/fuel injection equipment to remove all materials affected by ethanol. Older cars, such as XK engined Jaguars remained as they were built with no concerns/regards…

Personally, I wouldn’t use E10 in any of my cars, older Jaguars nor modern Jaguars/non-Jaguars unless the savings in the pump price of 91/92 octane E10 matters to you despite the engine/fuel system risk/down side…

sorry to put a strain on your heart & overload your blood pressure so Dr Tom prescribes you have a couple of stiff bourbons and a lay down…so for my E10 history, i have an XJ6 S2 1975 electronic ignition - which i’ve run on E10 90% of the time for about 12 years & never any problems with idle or revs at any level, no corrosion of fuel system & last long trip to QLD i averaged 13.2 Lts/100ks, my partner has a Honda crv 2000 same story & is her daily drive to work (about 450ks a week), i have a BA 2005 Ford wagon on LPG & only use the E10 for starting, so believe it or not - it is the real story.

1 Like

Good to hear Tom, given this issue was raised on XK forum you had me worried - there is just so much misinformation re Ethanol I thought best to clarify the facts to those interested in this subject…
Having said that, the Ethanol may not be a problem with 1975 presumably Strombergs - although I did own a 1977 4.2 XJL about 40 years ago (lovely car in my experience despite all the then and now S2 detractors), I never really had a good look/understanding at the metallurgy of the Stromberg fuel system apart from the troublesome AED. Still, you must be a gentle driver, if you are happy with the 91 octane fuel of E10 (in Australia). With all my S2 [XK], S3 [XK], XJ40, X302 [S/C] and current X351 [S/C] Jaguar XJs, although all designed for 95/6 Octane for Australian spec new, I always use 97/8 Octane…

Regardless, I still might have a couple of single-malts…

1 Like

i have twin HS8 Su’s, only have readjusted them twice since i bought the car in 2009, once was a full bench rebuild about 12 years ago, i eliminated the AED the week i got the car, since have fitted a manual choke system (down draft butterfly type) & created my own semi AED which activates only on cranking…just been in the garage with a warm up to move out for a wash/polish… take the woman for lunch saturday… i have a cruise control fitted & known to be a bit of a led foot at times (ex drag racer)
forgot to mention my choke system has an adjustable fast idle solenoid fitted

Perhaps another consideration: I understand that one argument for avoiding ethanol in engines is to do with how often they are used and the moisture absorption qualities of ethanol. Thought that in addition to avoiding adverse reactions with the fuel system components, running non-ethanol might help reduce moisture and corrosion in the fuel tank?

My XK120 OTS spends a lot of time curled up asleep in the garage so thought that buying regular smaller quantities coupled with running Shell 98 might help retain a reasonable octane rating by the time it is used and, if Shell marketing is to be believed, might include some other beneficial ingredients.

That said I understand that it is also recommended that fuel tanks be kept very full to avoid space for air, moisture and corrosion.

i’ll post my link again on fuel tech info, going to show my age but way back in the “old days” it was common for the ‘old guys’ then to drop a bit of clear alcohol in the fuel tank to dissipate water, anyway as you may have read my previous posts on this page, never had a problem with E10.

Hi all,

Same story here: in the last 26 years i used e5, 10 and 15 without distinction in a series bmc engines, w115 mercedes and V8 turbo Bentley, as well as AJ6 and my XK without any issues.

I note that in the Bentley and the XK, o rings were changed to e85 compatible neoprene, just as service items. 123 ignition would allow the puris to adjust advance (but also before I installed it, i really had no issues).

I also note: no pinging even at 4.5k rpm and more at hogh ambient temperatures.

Only note that: Water will decant, so high ethanol fuels are not adequate for long term winter storage.

Bis note: e5/10 sold in the EU is 95. E5 sold in some countries can be 98.

1 Like

luis, thanks for your feed back, i hope our original poster is noting all this, to add to the old guys adding to the petrol tank, they would pour a pint of mentholated spirits in to combat any water or vapor

Most folks around here use Stabil formulated for alcohol fuels for storage. It works well for mowers over winter and seems to prevent oxidation of the aluminum in the carbs.

Thanks for all comments but now I know less than when I started. I should have stated I’m asking the question about an all original '53 XK 120. Should I only use octane above 96 and what should I add to the fuel to combat the destructive nature of the ethanol?

XK specialists Twyford Motors produced an article on E10 a while back:

Thank you. I am quite familiar with the aforementioned causes and problems but his doesn.t address our problems here in the US.

Ron, there is no destructive nature in ethanol. Its just a different composition in fuel that can attack components that are otherwise easily replaceble as service items. As ethanol is widespread and frankly in a 70 y.o. car, I see no issue, just replace the orings and the very few hoses. As for winter storage, you need the commercial additives to avoid water separation

1 Like

I too am in California. I use Star Tron purchased at Walmart. It comes in different concentrations. I buy it in their marine department and not the auto dept as it is cheaper.

Ron… check out your local light aircraft club/field…they will probably have high octane ethanol free fuel…Steve

1 Like

whew–is ethanol free available at boating marinas? or for farm equipment? Luckily here in WA state, USA, normal gas, no ethanol is readily available at many fuel stations.amazing as WA state is fanatically eco crazed–but it is also very rural in many areas and Puget sound and lake boating is wide spread. Back to what to do if you have ONLY ethanol laced fuel and can’t get it someplace. First–not only may it eat older rubber compounds and some metals, but it also has a short shelf life–about 30-60 days, and it can gel and get gummy, It also attracts water from air humidity–another reason marine use does not like it. There are additives to help stablilize it, so it does not gel as quickly, additives that help pass water thru (yellow bottle HEET and similar) but I am not aware of additives that combat its hungriness for some metals. You can replace all fuel line rubber hoses with modern ones that resist ethanol, but as to the metal in the carb–I do not know of a solution. Beyond all that, then we have to talk about “lead”. The XK engine does have hard valve seats, however lead still has advantages in older engines is how it "softens " the blows of valve to seat, which is how the lead worked. I add some lead substitute–no harm done and some valve seat cushioning–even if not needed.
If you do find no ethanol, most of it is not branded–and little known about the additive package–I d still use STABIL or similar, and I’d add some “injector cleaner” . If periods of non use, add the “HEET” water remover now and then. Stabil products can help the fuel not spoil for about a year. Startron is a popular additive with the boating people.

Only 95 ROZ E10, 8:1, 9:1, HD8 with ASC, no issues in over two years.

When we filled the E Type up with E10 it took less than half an hour, then it overheated. It had nothing to do with the petrol but this is how the blaming can begin.

1 Like