outboard petrol in Cars?

[Avocet]

I used to take my son Kart racing every weekend and only once did he put mixed 2 stroke fuel in our Car.............

The only weekend I was unavailable.

10 litres of fuel mixed at 15 to 1 ratio was enough to gum the piston rings solid resulting in serious piston slap and a destroyed cat.

I am talking about 10 litres of fuel in an empty tank followed by thrashing the car on the motorway for 3 hours.

I have happily put 5 litres in and then topped the tank up to the brim with fresh fuel since.

2-stroke oil shouldn't bother the cat. I'm wondering whether in this (very extreme) case, once it had gummed up the rings, whether it was the car's own engine oil that started to blow past the rings, and then increased the crankcase pressure to the point where the engine started running very weak (because of all the extra crankcase fumes being forced into the inlet manifold), thereby causing repeated misfires and the massive quantity of unburned fuel entering the cat killed it off?

Just to put it into perspective, the handbook for my wife's last car stated that up to 1000km per litre of engine oil consumption was NORMAL! Again ,I don't think that IS normal, to be honest, but it gives some indication of just how much engine oil a cat can cope with.

 

[bikerbill]

I don't think old petrol turn to jelly and not fully convinced it goes off. However, 3 years ago I bought a Pan European motorcycle that had been off the road for 7 years. After putting fresh petrol in the tank and a new battery it started first time and ran sweet without any misfires. Perhaps the carbs and tank were drained before I bought it, don't know. However, 2 years ago I bought a Suzuki GSX 750 that had been off the road for a number of years. I had to take off the carbs then strip down and clean. The carb bowls had evidence of gumming up and the jets were blocked with crud. Don't know what the conclusion is except that perhaps Honda are better than Suzuki

 

[chewi]

I don't think old petrol turn to jelly and not fully convinced it goes off.

I have been keeping my outboard fuel in a can in the tender for 20yrs. Only this year has it given trouble because I keep the cans in the daylight, so nigel (post 19) is right that the daylight can kill it if kept in ordinary cans. My experience is that the temperature cycling causes enough condensation to separate the recent bioethanol additions from the petrol.
The ethanol settles at the botttom and the carburettor will not work.


More recently I have stored the cans in a dark box, and that seems to have improved it, which stacks up with what Nigel says.
So for those that say it doesn't go off, it certainly can go off, and is more likely to with recent formulations of petrol, but you might avoid it by storing it well, even if only accidentally.

BP tell me their "BP Ultimate" fuel has no ethanol, so I will be using that next season, and draining the carb so I don't have the current ethanol corroding it when the petrol has evaporated over the winter.

 

[clyst]

I have some left over petrol mixed with outboard oil for my two stroke. Rather than leave it to get stale over winter is it safe to put it in my car?

50 to 1 mixture.

By the time it's mixed with the cars petrol it ain't going to be anything like 50 to 1 especially if it's near full .

 

[reeac]

2-stroke oil shouldn't bother the cat.

Just to put it into perspective, the handbook for my wife's last car stated that up to 1000km per litre of engine oil consumption was NORMAL! Again ,I don't think that IS normal, to be honest, but it gives some indication of just how much engine oil a cat can cope with.

I just did a quick sum: 1000km. is 600 miles which, at 40 mpg. is 15 gallons which is 68 litres so up to 1 litre of oil burned along with 68 litres of petrol is OK. That's a "mix" of 1 in 68 which is in the typical modern outboard fuel range. All makes sense unless low ash outboard oil contains any "nasties" that cats. don't like.