Two stroke petrol for cars

Only use it if you already need a new catalyser anyway. How much is a little? If its enough to be worth keeping, then put it in a [properly sealed light proof strorage can. Preferably dont leave too much air speace.

It will be fine next spring. I drain the carb on my Yam 2 but leave the fuel in the tank. never ahd a problem yet.
 
There is nothing in two-stroke oil that will damage a catalyst. In fact, some two-stroke mopeds and similar vehicles have catalysts that are perfectly long-lived. Some info on the topic here indicates that four-stroke engine oil is far worse than two-stroke for poisoning catalyst. Temperature elevation is more of a problem with two-strokes but this will not be an issue in the volumes we are talking about here.
 
I use up surplus 2-stroke mixture in my 4-stroke Honda mower. Never a problem - not even a sign of smoke in the exhaust and I can't remember ever changing the plug.
 
I did it a few times on my old car. It's already 50:1 mix so adding a litre to 50 litres of petrol will give you a 2500:1 mix. I don't believe that would do any harm at all.
 
Plenty of cars burn a bit of oil anyway, and the cats are remarkably tolerant. Mrs. Avocet's old Alfa 156 used to get through about a pint of oil every 500 miles and the cat was never changed. Always passed it's MOT on emissions without and trouble, and had about 85,000 miles on it when we sold it.
 
Plenty of cars burn a bit of oil anyway, and the cats are remarkably tolerant. Mrs. Avocet's old Alfa 156 used to get through about a pint of oil every 500 miles and the cat was never changed. Always passed it's MOT on emissions without and trouble, and had about 85,000 miles on it when we sold it.

The latest cars are very intolerant of extra oil, to the extent newest engines often have to be run on low ash oils to save fouling the cat and or dpf.

A lot of cars with early fitment of cats will meet their emission levels without a cat there at all, and until recently, cat deletion was a viable option at mot or cat breakup time.

rules have been changed now though.
 
Quite common practice to put a bit or Two Stroke oil in every tank of diesel into the latest Land Rover Defenders. The same goes for lorries and other diesels cars, it's meant to improve MPG, give quieter running etc... I don't but people swear by it!

You could always poor it in my tank...

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Blimey! Did they forget to put the rings in when they built it? I never had to put any oil in my Honda between services until it was 13 years old and 200,000 miles on the clock.

Alfas are famous for "liking a bit of oil". Her current Nissan is like your Honda. When we first got the car, I bought a litre of oil for top-ups - that was 4 years ago and I've still got it! I suspect most of it was valve guides (though we bought it with barely 20,000 miles on it and it was always like that - never got any worse). To be honest, even the handbook said that up to 1000 km per litre was acceptable. That was a 1999 car. It didn't visibly smoke either.
 
The latest cars are very intolerant of extra oil, to the extent newest engines often have to be run on low ash oils to save fouling the cat and or dpf.

A lot of cars with early fitment of cats will meet their emission levels without a cat there at all, and until recently, cat deletion was a viable option at mot or cat breakup time.

rules have been changed now though.

Petrol cars are still fine. The cats are remarkably tolerant of oil. I think it's the diesel particulate filters that really don't like burnt engine oil. Oddly, I have an old Alfa V6 (1989, so pre-cat) and it will ALMOST meet cat emissions levels for CO and HC but it can't keep it's lambda within limits.
 
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