Old 2-stroke fuel

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Anyone know why 2T shouldn't be used in a car with a cat?

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Engine oil will destroy a cat so that it no longer works. Its not clear whether 2T does the same, but 'whatta mistaka to maka' if it does with the cost of a new one!
 
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Description is interesting

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Diesels (probably not the more modern common-rail type) will run with a bit of petrol in the tank. If you ever make the mistake of starting to fill a diesel with petrol STOP, move to the diesel pump and carry on. They reckon half a gallon of petrol in a tank of diesel isn't a problem.

(I've done it with an old Rover 218D)

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Done it both ways-old 1.8 diesel Cav-
Petrol into diesel. Caught it late-qtr tank- strange garage, adverts all over nozzle.
Bled it mostly dry, topped up with diesel, ok, bit of smoke, performance improved. cheaper than Soltron! /forums/images/graemlins/grin.gif

Did it again with an 04 cat Jazz last month- caught it much quicker; easier-petrol nozzles only fit new petrol cars properly- only about 3 litres diesel in. topped tank up, refilled since, no problems.
Lesson -if the nozzle doesnt fit 1st time, don't stubbornly persevere /forums/images/graemlins/laugh.gif
 
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[ cheaper than Soltron! /forums/images/graemlins/grin.gif
I like that


Lesson -if the nozzle doesnt fit 1st time, don't stubbornly persevere /forums/images/graemlins/laugh.gif

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So many peeps do
I have had a Filling Station.
It's Unbelievable /forums/images/graemlins/grin.gif
 
I know the conditions that an outboard will work in are different to a chainsaw (although you would expect an outboard designer to build an engine which works at the optimum temperatures, much like the chainsaw designer), but I'm not convinced that the composition of a 2 stroke oil for one is going to be vastly different to one designed for the other.
For a manufacturer to state that it can be used in cat equipped engines seems at odds with the normal "arse-covering" small print.

A diesel engine runs on "oil" albeit another different composition, cats are now commonplace on diesel engines - even 2 stroke diesels are being fitted with them.

Any 4 stroke engine will burn a small amount of oil during normal use, it's what lubricates the piston/rings/bore! There will also be a small amount on valve stems.

Are engine breather pipes still routed back to the inlet manifold?

I really want to find out is if this is just another urban myth.
 
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not convinced that the composition of a 2 stroke oil for one is going to be vastly different to one designed for the other

[/ QUOTE ] The viscosities are different, at least they were when I tested them. Slightly higher viscosity for the hotter running air cooled engine. May be other differences, I would not know, but most garden machinery 2T oil is labelled as also being suitable for small outboards. Perhaps with the big outboards one would want to be more careful, they cost too much to take risks with.

I think with the 2t oil and cats you are applying the same logic as I would. All car engines burn a little oil. Maybe burnt only at very low levels there is no problem but a slug of perhaps 200cc of oil from 10l of 2t mixture in one tankful of fuel could just be too much. Don't know, silly to risk it. Even the people who have inadvertently filled their petrol tanks with diesel will probably not realise that it has shortened the life of the cat even if it has.
 
Done some more digging but most cat manufacturers warn that almost anything will damage the cat, dunno if that's more arse-covering.
Maybe it's one that is difficult to find an answer to, most folk wouldn't risk it because of the possible cost of replacement. The ones that have and survived, as you said, don't know if they have shortened the life of the cat.

My car is too old to have a cat, so maybe I'm lucky (to have an old car /forums/images/graemlins/confused.gif ). All old petrol has gone in (with plenty of fresh fuel in the tank already) without a problem.

I have had trouble running outboards on old petrol though.
 
As stated before -add some fresh petrol/oil mix (say 25%) and would be surprised if you can tell the difference. Have done it myself almost every year and no problems (famous last words... ??)

You are 100% correct to drain down the carb etc as gumming as a real problem when petrol evaporates over winter, but would advise a drop of oiley fuel kept in the tank and shaken every few months if its a steel tank for corrosion reasons.
 
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A diesel engine runs on "oil" albeit another different composition, cats are now commonplace on diesel engines - even 2 stroke diesels are being fitted with them.



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...but 2 stroke diesels don't use crank case scavenging, and have conventional bottom ends with normal lubrication....
 
Hi Mick,

To answer your question directly the answer is no it will not do any harm.

As you will see from the previous posts there is some possibility that it may impair starting. However, in my humble opinion most such problems with two strokes only arise from leaving fuel in the carburetter bowl to evaporate over the winter and turn into an oily mess. For the (ahem) years that I ran well maintained two strokes I never had less than a single pull to start them in the spring on last year's juice.

Technically, the resulting lean mix from running the card dry at season's end is not good for an engine but nonetheless, that is still all I would do fuelwise with a two stroke outboard as well as shutting the tank vent of course.
 
That's why I said the newer common-rail engines probably wouldn't be as forgiving. They have very high pressure fuel pumps and the system is pressurised all the time.

Also, 50% is pushing it a bit. /forums/images/graemlins/grin.gif
 
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However, in my humble opinion most such problems with two strokes only arise from leaving fuel in the carburetter bowl to evaporate over the winter and turn into an oily mess.

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I'm afraid I find that a bit patronising.

If the engine is running fine and when filled with old petrol then ceases to run at all that is a pretty strong indication that it is the fuel that is wrong, not gunk in the carb. Especially if when you add an equal quantity of fresh fuel it works.
 
You're misunderstanding what he said. There's no doubt that a lot of problems first start of the spring do come from leaving the float bowl full of 2T mixture. The volatiles flash off whilst in storage leaving behind a nasty concoction of gums and oils - which will often clog up the fine jets of the carb.

No doubt that the best practise is to turn off the fuel and let the engine run the carb dry - good practise on old designs like Seagulls as a matter of routine, but still worth doing on Jap motors before a long lay up. Incidentally, also a good idea with 4 strokes - speaking as someone who has just had to spend several hours de-clogging twin Dellortos that had been left full of fuel.

Getting rid of old 2T - thats what the motor mower is for. Will run on damn near anything in my experience
 
At the end of the season I usually have about half a tank (2.5 litres) left at a 50-1 mix. to get rid of it I've always added about a litre at a time to a tank full of petrol, roughly 50 litres I reckon this must give a mix of 2500-1. I don't think this would cause any harm to my cat. Hope I'm right.
 
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