XJR was at the body shop for 3 months (another story!) when it returned with 3/4 tank of gas, it ran rough. I tried "seafoam" to "dry the gas" but the old girl just backfired and set codes like; "random misfire"
"damage to Cat." "help me Rhonda". It was frightening!
After reading through all the posts; I was sure that the ECU had been destroyed by jump starting. I had a spare Crank position gizmo, so I replaced that. ( In the meantime I had siphoned out all the fuel and replaced it) Still no luck so I am now certain on the ECU being ruined.
Just to calm myself; I took the plugs out and cleaned them.
Surprise! the old smooth idle and quiet running of the magnificent Jaguar automobile.
Just goes to show; Do the simple things first.

 

XJR singing the Beach Boys tune

so the plugs were causing all the issues or the gas?

 

Seafoam does not 'dry the gas'. It's probably one of the most ineffective and inappropriate products around for modern engines.

 

I am thinking the gas fouled the plugs so the issues continued after I
changed out the gas

 

I don't understand the concept of "drying the gas" anyway. Seafoam is supposed to clean carbon deposits, the garage that cleaned the EGR tube on my son's care soaked it in seafoam.
There are dozens of products that claim to remove or nullify Ethanol, if there are any of you guys that know about this stuff; share it.

 

There are no such products or any need for them.

 

Try some TC-W3 outboard oil at a ratio of 1.9 ml per litre works wonders
this guy Been testing is in the states got me onto it
Its a long read but interesting I now use it in my 4 stroke engines
I have been using it in my diesel engine made a unbelievable difference in my 07 Jeep GC CRD engine
Decided to try it out in my xjr she runs as smooth as she always had a rough idle now gone you could stand a 50 cent piece on the engine its that smooth very economical as well 1.9ml per litre of fuel is nothing
I buy it in bulk 20 litre drum costs me 6 dollars a litre drum has lasted a year not bad using it in all my vehicles

 

I just checked out that link.
It sounds pretty reasonable to use the 2-stroke Pennzoil marine oil in the petrol tank.
The guy that did the original post in that link recommended 1 fl oz per 5 gallons

Assuming he's talking US gallons (3.8 litres) not Imperial (4.5 litres), and a fluid ounce is 29.5 ml, then the ratio would be 1.5mL oil per litre of petrol.

 

It's going to be a long read

Any more details since you have a year under your belt with this?

 

Bought some oil for this purpose this morning
the recommended Penzoil was not available on a Saturday morning at my boat shop, so I bought Evinrude fully-synthetic XD-100 which is supposedly the ultimate synthetic 2-stroke outboard oil.
I haven't put it in the Jaguar yet (it's having some work done) put mixed 75mL into the 60 litre tank of my Subaru - then drove 65 miles with no problems.
I will try the Jag later in the week and report back after a couple of tanks of fuel

 

The TC-W3 does not have to be synthetic the cheapest will do its the additive pack in the TC-W3 that you want

Less is more if the mix works out to a fractional number go the less amount not the more if you get what I mean

My car usually works out to 147 ML per tank but I have never been able to get that amount of fuel in the tank so do like a 130 to 135 ML its all about experimenting

I figured my XJR goes best with 1.9 ml per litre of fuel
In the diesel I use 3.2 ml per litre of diesel

 

I would agree with that.

I've read as much as I can take of that other website and am still a little lost as to what problems they're trying to fix/avoid. Putting 2 stroke outboard motor oil in the fuel tank of a 4 stroke auto engine is a new one on me.

 

Just read the first post on (been testing) by Sarge he explains what he is trying to achieve

I was also skeptical at first

I had been using the TC-W3 in my diesel jeep grand Cherokee and before that my Citroen C5 diesel and had been getting fantastic results been using it in the jeep for 2 years now

I always get people asking me if its a diesel when I say yes they just cant believe how quiet it is I usually have to open the bonnet to show them the engine

So a couple of mates asked me what I had done to my XJR the exhaust note was deeper and the idle was smoother
I told them I was experimenting with TC-W3 after using it in my diesel jeep and reading the various posts on it decided to try it

At first I thought yeah its smoother and the car seemed more responsive but that could have been psychological as well
I then filled my tank on the XJR to the brim while the car was on an angle didn't have the measuring jug with me so drove the car home this was minus the TC-W3
First thing I noticed the miss that this car has always had was back also when I pushed the throttle the car was not as responsive got home tried to add the TC-W3 but as soon as I opened the tank fuel came out so I drove around for a while tried again fuel still came out so I went down the road parked half on the gutter facing down hill aha I was able to add the TC-W3 drove away saw a hole in traffic hit the throttle was instantly pushed in the seat drove around prodding the accelerator trying to feel it out feels awesome
I have had some fast cars when younger and still have a few motorbikes I have tried octane boosters system cleaners you name it some of them cost ridiculous money none gave me that seat of the pants feel the TC-W3 does

 

Too late for objections or second thoughts.

It's already in the tank as of yesterday. Castrol 2 stroke with the correct TC-W3 and JSAO rating.

150 ml in a full 81L tankful. So, 1.85 ml per liter.

There is also a reference video of a jar of water sitting on the SC at idle for later comparison.

The additional benefits noted in the threads, both the original and several current threads at the usual canonical oil argument site included:

- smoother idle
- quieter operation
- faster starts
- quieter fuel pumps
- and one poster actually said: "and I quit replacing fuel pumps".

The prime goal as stated by Sarge was longevity of fuel system components in the face of ethanol and any improvement in mileage was considered a "bonus".

Given the frequent wailing about fuel pumps on JF, just keeping the fuel pump alive would be enough reason to do it. Especially for some of the owners who have suffered repeated fuel pump failures only months apart. $700.00 buys an awful lot of blue oil.

I fully acknowledge that some of the miracle cures could have been badly maintained vehicles which had their piston rings freed up by this treatment. However, the expectations and anecdotal results are well within the realm of possibility given the mechanics and chemistry involved.

The deeper exhaust note has been mentioned by several people.

One person had a very clever explanation for the small quantity. He tells people:

2 ounces is exactly the recommended dose for 10 US gallons.

 

They also lay it out as a straight ratio of 1:500 as the base recommendation, and the original poster of the thread has upgraded personally to 1:400 as being best for his vehicles.

So, strictly speaking you would be using 2.0ml per litre of petrol if you wanted to match 1:500.

 

Thanks, I read that.

For what it's worth, and as stated many times here, I've been using E10 gas for 20+ years and have experienced NONE of the issues that this Sarge fellow is afraid of. Don't know of anyone that actually has either.

If they were an issue, I'm not sure that adding ~.19% of anything would make much difference either way. An elderly friend had an expression- don't worry about adding too much mayonnaise to the axle grease. I won't spoil that taste of the grease at all.

 

Awesome Plums
Cant wait to see what you think again its not much oil for the amount of fuel looking forward to seeing the jar of water on the Eaton test

 

On occasion I run my 4 stroke tractor mower from the contents of my mixed 2 stroke Jerry can.

It does seem to run a little differently.

Over here we have hellishly strict emissions testing.

Would adding 'oil' to the tank over a long period adversely affect outputs/cats etc?

Genuine question, I don't know the answer.

 

Richard-

Typically 2 strokes require a 50:1 oil to fuel mix. The fellow above is operating at 1/10th that ratio or 500:1, hence my wondering if such a lean mix would make any difference at all.

 

It could be a bit of a snore fest.

The "before" video shows surprisingly little movement on the surface of the water. Perhaps having a lid on the jar dampened the movement. Coming from a Supra with the excellent 7M-GTE, the SC V8 seems rougher than that by touching the SC cover. Since the car has not been moved, maybe I will try again. The idea was originally touched on by a poster in one of the other threads but he used a glass of water ... so no lid. But he was talking about having to hold the glass because the water was "sloshing around" ... that's why I "cleverly" went for the lid. Too clever.

The other factor is getting some decent mileage. Except for long drives it takes over a month to run through a tank of gas. Economical but not so much fun.