Is it bad to leave petrol in a car's fuel tank for a long period of time?

Say you don't use a car for a whole year and there is a full tank of
petrol just sitting there.

Will the petrol lose its potency or evaporate or something?

On 6/11/21 4:09 pm, Max wrote:
> Is it bad to leave petrol in a car's fuel tank for a long period of time?
>
> Say you don't use a car for a whole year and there is a full tank of
> petrol just sitting there.
>
> Will the petrol lose its potency or evaporate or something?

Yes, and no, it depends.

The fuel will lose the volatile components to evaporation over time due
to oxidation. That will make the engine harder to start. That oxidation
may not apply so much to modern cars with emission control systems
fitted to fuel tanks. Evaporation may still occur but the presence of
oxidizing air is limited since fuel systems are sealed and fitted with
charcoal canisters and vapour purge systems. The days of the simple vent
hole in the fuel tank cap are *long gone*

https://www.carparts.com/blog/evaporative-emission-control-evap-system-101-the-basics/

If the fuel has any ethanol in it, then it will definitely not keep for
extended periods. This is more an issue with outdoor power equipment or
boats since their use is generally seasonal so they tend to be stored
over winter months. What happens is the ethanol separates from the
petrol and forms a brown sludge which doesn't do fuel lines,
carburettors, etc. any good at all. As well, the fuel tends to absorb
water so can promote bacterial growth and *corrosion*. Diesel engines
are prone to this in tropical climes but fuel injected petrol engined
cars with a fuel return line and swirl pot in the tank are also prone to
bacterial issues when running ethanol adulterated petrol. The warm fuel
running back to the swirl pot creates ideal conditions for bacterial
growth in the tank.

If you are concerned at all, you can simply use a *fuel conditioner*

https://www.supercheapauto.com.au/dw/image/v2/BBRV_PRD/on/demandware.static/-/Sites-srg-internal-master-catalog/default/dw713b81cc/images/223945/SCA_223945_hi-res.jpg

Fuel in the tank is quite Ok for 3 - 6 months without any additive.
According to the directions, the above keeps the fuel stable for 12
months. The longest I have gone without a tank refill is one month so I
have never needed it. Also, I don't run E10 either but even 91 can be
*adulterated* with ethanol these days.

This gives you some idea of the joys of ethanol laced fuel and why I
avoid it.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4513208/

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 6/11/2021 4:09 pm, Max wrote:
> Is it bad to leave petrol in a car's fuel tank for a long period of time?
>
> Say you don't use a car for a whole year and there is a full tank of
> petrol just sitting there.
>
> Will the petrol lose its potency or evaporate or something?

**When my idiot brother left fuel in the tank of his VH Commodore (253
V8) wagon for 15 years, it required a complete replacement of the fuel
tank and thorough clean of the fuel system. So, bad idea to let fuel sit
in a car for too long.

On 7/11/2021 5:19 am, Trevor Wilson wrote:
> On 6/11/2021 4:09 pm, Max wrote:
>> Is it bad to leave petrol in a car's fuel tank for a long period of
>> time?
>>
>> Say you don't use a car for a whole year and there is a full tank of
>> petrol just sitting there.
>>
>> Will the petrol lose its potency or evaporate or something?
>
> **When my idiot brother left fuel in the tank of his VH Commodore (253
> V8) wagon for 15 years, it required a complete replacement of the fuel
> tank and thorough clean of the fuel system. So, bad idea to let fuel
> sit in a car for too long.

I had a motorbike in storage for many years with petrol left in the
tank. when I decided to sell it I couldn't start it. turned out the
cause was 'stale petrol'.

--
"A mans got to know his limitations"
- clint Eastwood as Dirty Harry

On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:

> I had a motorbike in storage for many years with petrol left in the
> tank. when I decided to sell it I couldn't start it. turned out the
> cause was 'stale petrol'.
>
It used to happen with dual-fuel cars, if only LPG was used for ages, then one day driver needed petrol to get home, shit out of luck.
Seems RON91 went stale quicker than RON98, I don't know why that would be.

On 7/11/21 11:00 am, Falscher Bruce wrote:
> On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:
>
>> I had a motorbike in storage for many years with petrol left in the
>> tank. when I decided to sell it I couldn't start it. turned out the
>> cause was 'stale petrol'.
>>
> It used to happen with dual-fuel cars, if only LPG was used for ages, then one day driver needed petrol to get home, shit out of luck.

The problem there was that the carburettor would be run dry of petrol.
That's bad, at least for any carb that has diaphragms and plunger seals.
These would dry out and go brittle. Then they wouldn't work.

> Seems RON91 went stale quicker than RON98, I don't know why that would be.
>
98 is the only current fuel guaranteed not to have *any* ethanol. Not
the case with 91 & 95. E10 has 10%, 91 can have lesser quantities -
legally. Remember the little sign on 91 pumps saying "No Ethanol"? Did
you notice that, some time back, these little signs were all *removed*.
Did you ever wonder why that was? You can still get ethanol adulteration
in 91, don't use 95 so never tested that. When you start your car first
thing, if your exhaust smells a bit like you've had a weed party, you
might have ethanol in the fuel. Need to do the test before the catalytic
converter lights off though.

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 10:16 am, Yosemite Sam wrote:
> On 7/11/2021 5:19 am, Trevor Wilson wrote:
>> On 6/11/2021 4:09 pm, Max wrote:
>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>> time?
>>>
>>> Say you don't use a car for a whole year and there is a full tank of
>>> petrol just sitting there.
>>>
>>> Will the petrol lose its potency or evaporate or something?
>>
>> **When my idiot brother left fuel in the tank of his VH Commodore (253
>> V8) wagon for 15 years, it required a complete replacement of the fuel
>> tank and thorough clean of the fuel system. So, bad idea to let fuel
>> sit in a car for too long.
>
>
> I had a motorbike in storage for many years with petrol left in the
> tank. when I decided to sell it I couldn't start it. turned out the
> cause was 'stale petrol'.
>
>
Very common. Yet I bought a car once that had sat under a tree for some
3 years without being started. Once I changed out the starter, it fired
right up and ran smooth as hell. Discovered that the odometer reading
was accurate, thought it had been clocked a couple of times but it had
only 50,000 genuine kilometres from new on it. I thought it had way more
on it given the appearance of the car. Drove it 50 kilometres home, gave
it a good wash and general clean up and it looked like a new car. Best
$250 I ever spent on a car. Only 4 trivial items for a RWC too, total
cost on the road < $1,000.

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/2021 8:48 am, Xeno wrote:
> On 7/11/21 10:16 am, Yosemite Sam wrote:
>> On 7/11/2021 5:19 am, Trevor Wilson wrote:
>>> On 6/11/2021 4:09 pm, Max wrote:
>>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>>> time?
>>>>
>>>> Say you don't use a car for a whole year and there is a full tank of
>>>> petrol just sitting there.
>>>>
>>>> Will the petrol lose its potency or evaporate or something?
>>>
>>> **When my idiot brother left fuel in the tank of his VH Commodore
>>> (253 V8) wagon for 15 years, it required a complete replacement of
>>> the fuel tank and thorough clean of the fuel system. So, bad idea to
>>> let fuel sit in a car for too long.
>>
>>
>> I had a motorbike in storage for many years with petrol left in the
>> tank. when I decided to sell it I couldn't start it. turned out the
>> cause was 'stale petrol'.
>>
>>
> Very common. Yet I bought a car once that had sat under a tree for some
> 3 years without being started. Once I changed out the starter, it fired
> right up and ran smooth as hell. Discovered that the odometer reading
> was accurate, thought it had been clocked a couple of times but it had
> only 50,000 genuine kilometres from new on it. I thought it had way more
> on it given the appearance of the car. Drove it 50 kilometres home, gave
> it a good wash and general clean up and it looked like a new car. Best
> $250 I ever spent on a car. Only 4 trivial items for a RWC too, total
> cost on the road < $1,000.
>

My best flip was an old square body late 80's $50 Camry I bought through
the dealership with 6 months rego just paid. I was going to send it off
to the wreckers and hand in the plates for a quick buck but the car
drove so well and was so comfy that I put a new waterpump on and sold it
the following week to the first person who drove it for $1600.

On 7/11/2021 2:19 am, Trevor Wilson wrote:
> On 6/11/2021 4:09 pm, Max wrote:
>> Is it bad to leave petrol in a car's fuel tank for a long period of time?
>>
>> Say you don't use a car for a whole year and there is a full tank of
>> petrol just sitting there.
>>
>> Will the petrol lose its potency or evaporate or something?
>
> **When my idiot brother left fuel in the tank of his VH Commodore (253
> V8) wagon for 15 years, it required a complete replacement of the fuel
> tank and thorough clean of the fuel system. So, bad idea to let fuel sit
> in a car for too long.

Yep, a year is probably the longest you would ever want to leave fuel
sitting and less than that in hot climates.

On 7/11/21 12:23 pm, Clocky wrote:
> On 7/11/2021 2:19 am, Trevor Wilson wrote:
>> On 6/11/2021 4:09 pm, Max wrote:
>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>> time?
>>>
>>> Say you don't use a car for a whole year and there is a full tank of
>>> petrol just sitting there.
>>>
>>> Will the petrol lose its potency or evaporate or something?
>>
>> **When my idiot brother left fuel in the tank of his VH Commodore (253
>> V8) wagon for 15 years, it required a complete replacement of the fuel
>> tank and thorough clean of the fuel system. So, bad idea to let fuel
>> sit in a car for too long.
>
> Yep, a year is probably the longest you would ever want to leave fuel
> sitting and less than that in hot climates.

Yeah, I've seen fuel with all the lighter components evaporated off and
the residual looking more like a mix of kero and diesel - and about as
oily too. ;-)

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 5:19 am, Trevor Wilson wrote:
> On 6/11/2021 4:09 pm, Max wrote:
>> Is it bad to leave petrol in a car's fuel tank for a long period of time?
>>
>> Say you don't use a car for a whole year and there is a full tank of
>> petrol just sitting there.
>>
>> Will the petrol lose its potency or evaporate or something?
>
> **When my idiot brother left fuel in the tank of his VH Commodore (253
> V8) wagon for 15 years, it required a complete replacement of the fuel
> tank and thorough clean of the fuel system. So, bad idea to let fuel sit
> in a car for too long.

15yrs is way too long but most of the time 12mths should be ok.

--
Daryl

On 7/11/21 11:00 am, Falscher Bruce wrote:
> On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:
>
>> I had a motorbike in storage for many years with petrol left in the
>> tank. when I decided to sell it I couldn't start it. turned out the
>> cause was 'stale petrol'.
>>
> It used to happen with dual-fuel cars, if only LPG was used for ages, then one day driver needed petrol to get home, shit out of luck.

They would of had to have not used petrol for a very long time for it to
be a problem, I had 2 LPG cars and never had an issue with stale petrol.

--
Daryl

On 7/11/21 5:30 pm, Daryl wrote:
> On 7/11/21 11:00 am, Falscher Bruce wrote:
>> On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:
>>
>>> I had a motorbike in storage for many years with petrol left in the
>>> tank. when I decided to sell it I couldn't start it. turned out the
>>> cause was 'stale petrol'.
>>>
>> It used to happen with dual-fuel cars, if only LPG was used for ages,
>> then one day driver needed petrol to get home, shit out of luck.
>
> They would of had to have not used petrol for a very long time for it to
> be a problem, I had 2 LPG cars and never had an issue with stale petrol.
>
The golden rule with dual fuel cars was to run on petrol every now and
then to keep the fuel system (and the fuel) in good nick. Some people
never got that message. Back in the days of leaded petrol, it also
(supposedly) used to keep the valve seats in good nick.

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 5:28 pm, Daryl wrote:
> On 7/11/21 5:19 am, Trevor Wilson wrote:
>> On 6/11/2021 4:09 pm, Max wrote:
>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>> time?
>>>
>>> Say you don't use a car for a whole year and there is a full tank of
>>> petrol just sitting there.
>>>
>>> Will the petrol lose its potency or evaporate or something?
>>
>> **When my idiot brother left fuel in the tank of his VH Commodore (253
>> V8) wagon for 15 years, it required a complete replacement of the fuel
>> tank and thorough clean of the fuel system. So, bad idea to let fuel
>> sit in a car for too long.
>
> 15yrs is way too long but most of the time 12mths should be ok.
>
15 *months* is too long. My word, you have a penchant for stating the
obvious.

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/2021 5:30 pm, Daryl wrote:
> On 7/11/21 11:00 am, Falscher Bruce wrote:
>> On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:
>>
>>> I had a motorbike in storage for many years with petrol left in the
>>> tank. when I decided to sell it I couldn't start it. turned out the
>>> cause was 'stale petrol'.
>>>
>> It used to happen with dual-fuel cars, if only LPG was used for ages,
>> then one day driver needed petrol to get home, shit out of luck.
>
> They would of had to have not used petrol for a very long time for it to
> be a problem, I had 2 LPG cars and never had an issue with stale petrol.

Yep. Stale fuel in dual fuel powered cars was seldom if ever a problem.
Dried up fuel system components that had remained dormant for ages was
usually the problem.

--
--
--
Regards,
Noddy.

On 7/11/2021 5:28 pm, Daryl wrote:
> On 7/11/21 5:19 am, Trevor Wilson wrote:
>> On 6/11/2021 4:09 pm, Max wrote:
>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>> time?
>>>
>>> Say you don't use a car for a whole year and there is a full tank of
>>> petrol just sitting there.
>>>
>>> Will the petrol lose its potency or evaporate or something?
>>
>> **When my idiot brother left fuel in the tank of his VH Commodore (253
>> V8) wagon for 15 years, it required a complete replacement of the fuel
>> tank and thorough clean of the fuel system. So, bad idea to let fuel
>> sit in a car for too long.
>
> 15yrs is way too long but most of the time 12mths should be ok.

12 months is fine. Some people put cars into long term storage for a
year or more and the fuel survives just fine. You can also add fuel
stabiliser products which will extend the useful life of the fuel.

--
--
--
Regards,
Noddy.

On 7/11/2021 5:28 pm, Daryl wrote:
> On 7/11/21 5:19 am, Trevor Wilson wrote:
>> On 6/11/2021 4:09 pm, Max wrote:
>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>> time?
>>>
>>> Say you don't use a car for a whole year and there is a full tank of
>>> petrol just sitting there.
>>>
>>> Will the petrol lose its potency or evaporate or something?
>>
>> **When my idiot brother left fuel in the tank of his VH Commodore (253
>> V8) wagon for 15 years, it required a complete replacement of the fuel
>> tank and thorough clean of the fuel system. So, bad idea to let fuel
>> sit in a car for too long.
>
> 15yrs is way too long but most of the time 12mths should be ok.
>

**Some of the fuel leaked onto the garage floor. I hit it with degreaser
about five times and there was still some residue left. I can only
imagine what his fuel tank and fuel system was like. As I said though,
he is an idiot. Damned car is worth about $25k and he treats it like
that. Anyway, it has a new fuel tank, new carby and bits of the fuel
system have been replaced. It runs well and looks very nice. Still, is
was a couple of Grand he didn't need to spend.

On 7/11/21 6:54 pm, Noddy wrote:
> On 7/11/2021 5:30 pm, Daryl wrote:
>> On 7/11/21 11:00 am, Falscher Bruce wrote:
>>> On Sunday, November 7, 2021 at 7:15:55 AM UTC+8, Yosemite Sam wrote:
>>>
>>>> I had a motorbike in storage for many years with petrol left in the
>>>> tank. when I decided to sell it I couldn't start it. turned out the
>>>> cause was 'stale petrol'.
>>>>
>>> It used to happen with dual-fuel cars, if only LPG was used for ages,
>>> then one day driver needed petrol to get home, shit out of luck.
>>
>> They would of had to have not used petrol for a very long time for it
>> to be a problem, I had 2 LPG cars and never had an issue with stale
>> petrol.
>
> Yep. Stale fuel in dual fuel powered cars was seldom if ever a problem.
> Dried up fuel system components that had remained dormant for ages was
> usually the problem.
>
>
Why don't you just cut and paste what I wrote Darren, save yourself some
effort. LOL

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 6:59 pm, Noddy wrote:
> On 7/11/2021 5:28 pm, Daryl wrote:
>> On 7/11/21 5:19 am, Trevor Wilson wrote:
>>> On 6/11/2021 4:09 pm, Max wrote:
>>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>>> time?
>>>>
>>>> Say you don't use a car for a whole year and there is a full tank of
>>>> petrol just sitting there.
>>>>
>>>> Will the petrol lose its potency or evaporate or something?
>>>
>>> **When my idiot brother left fuel in the tank of his VH Commodore
>>> (253 V8) wagon for 15 years, it required a complete replacement of
>>> the fuel tank and thorough clean of the fuel system. So, bad idea to
>>> let fuel sit in a car for too long.
>>
>> 15yrs is way too long but most of the time 12mths should be ok.
>
> 12 months is fine. Some people put cars into long term storage for a
> year or more and the fuel survives just fine. You can also add fuel
> stabiliser products which will extend the useful life of the fuel.
>
>
>
Why don't you cut and past what I wrote Darren? Save yourself some
effort. LOL

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 7:13 pm, Trevor Wilson wrote:
> On 7/11/2021 5:28 pm, Daryl wrote:
>> On 7/11/21 5:19 am, Trevor Wilson wrote:
>>> On 6/11/2021 4:09 pm, Max wrote:
>>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>>> time?
>>>>
>>>> Say you don't use a car for a whole year and there is a full tank of
>>>> petrol just sitting there.
>>>>
>>>> Will the petrol lose its potency or evaporate or something?
>>>
>>> **When my idiot brother left fuel in the tank of his VH Commodore
>>> (253 V8) wagon for 15 years, it required a complete replacement of
>>> the fuel tank and thorough clean of the fuel system. So, bad idea to
>>> let fuel sit in a car for too long.
>>
>> 15yrs is way too long but most of the time 12mths should be ok.
>>
>
> **Some of the fuel leaked onto the garage floor. I hit it with degreaser
> about five times and there was still some residue left. I can only

It will have well and truly soaked into the concrete floor. You will
need a degreaser that will bring it up out of the concrete so you can
wash it away. Look for something like the description in this ad;

https://www.amazon.com/dp/B0046O5YMA?tag=garagetooladvisor-20

Note, I am not recommending the above product, just alerting you to the
requirements of any degreaser you decide to use.

FWIW, inside garage floors are meant to be impermeable to grease, oil
and the like. Once you get the floor clean, you might want to consider
using a good quality *sealer* on it.

> imagine what his fuel tank and fuel system was like. As I said though,
> he is an idiot. Damned car is worth about $25k and he treats it like
> that. Anyway, it has a new fuel tank, new carby and bits of the fuel
> system have been replaced. It runs well and looks very nice. Still, is
> was a couple of Grand he didn't need to spend.

--

Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 7/11/21 7:13 pm, Trevor Wilson wrote:
> On 7/11/2021 5:28 pm, Daryl wrote:
>> On 7/11/21 5:19 am, Trevor Wilson wrote:
>>> On 6/11/2021 4:09 pm, Max wrote:
>>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>>> time?
>>>>
>>>> Say you don't use a car for a whole year and there is a full tank of
>>>> petrol just sitting there.
>>>>
>>>> Will the petrol lose its potency or evaporate or something?
>>>
>>> **When my idiot brother left fuel in the tank of his VH Commodore
>>> (253 V8) wagon for 15 years, it required a complete replacement of
>>> the fuel tank and thorough clean of the fuel system. So, bad idea to
>>> let fuel sit in a car for too long.
>>
>> 15yrs is way too long but most of the time 12mths should be ok.
>>
>
> **Some of the fuel leaked onto the garage floor. I hit it with degreaser
> about five times and there was still some residue left. I can only
> imagine what his fuel tank and fuel system was like. As I said though,
> he is an idiot. Damned car is worth about $25k and he treats it like
> that. Anyway, it has a new fuel tank, new carby and bits of the fuel
> system have been replaced. It runs well and looks very nice. Still, is
> was a couple of Grand he didn't need to spend.

Fuel that old is certainly very nasty, the donor car my son bought for
the engine upgrade in his Daihatsu had been sitting for about 10yrs, it
wouldn't start because the fuel pump had seized solid, had to remove the
tank to access the pump and the smell was disgusting.

--
Daryl

Daryl <dwalford@westpine.com.au> wrote:
> On 7/11/21 7:13 pm, Trevor Wilson wrote:
>> On 7/11/2021 5:28 pm, Daryl wrote:
>>> On 7/11/21 5:19 am, Trevor Wilson wrote:
>>>> On 6/11/2021 4:09 pm, Max wrote:
>>>>> Is it bad to leave petrol in a car's fuel tank for a long period of
>>>>> time?
>>>>>
>>>>> Say you don't use a car for a whole year and there is a full tank of
>>>>> petrol just sitting there.
>>>>>
>>>>> Will the petrol lose its potency or evaporate or something?
>>>>
>>>> **When my idiot brother left fuel in the tank of his VH Commodore
>>>> (253 V8) wagon for 15 years, it required a complete replacement of
>>>> the fuel tank and thorough clean of the fuel system. So, bad idea to
>>>> let fuel sit in a car for too long.
>>>
>>> 15yrs is way too long but most of the time 12mths should be ok.
>>>
>>
>> **Some of the fuel leaked onto the garage floor. I hit it with degreaser
>> about five times and there was still some residue left. I can only
>> imagine what his fuel tank and fuel system was like. As I said though,
>> he is an idiot. Damned car is worth about $25k and he treats it like
>> that. Anyway, it has a new fuel tank, new carby and bits of the fuel
>> system have been replaced. It runs well and looks very nice. Still, is
>> was a couple of Grand he didn't need to spend.
>
>
> Fuel that old is certainly very nasty, the donor car my son bought for
> the engine upgrade in his Daihatsu had been sitting for about 10yrs, it
> wouldn't start because the fuel pump had seized solid, had to remove the
> tank to access the pump and the smell was disgusting.
>

If the stale fuel stunk, that’s an indication it was adulterated by
ethanol. It doesn’t even need to have been E10. 91 and 95 suffer from
degrees of ethanol adulteration but at much lower levels than 10%. The
ethanol, at levels below 40%, promotes bacterial growth and, if the fuel
system has a fuel return to the tank, even more promotion of bacterial
growth because of the heat generated in the swirl pot of the fuel tank.
Note too that the fuel pump is often *in* the fuel tank in modern fuel
injected cars. That is one of the prime causes of the smell. The bacteria
create an acid which attacks metallic components and the ethanol separates
from the petrol over time to form a brown nasty sludge which clogs the fuel
system, a worse combination you would not find.

——-
Xeno