On Thu, 29 Aug 2019 12:18:00 +0100, Chris Hogg wrote:

On 29 Aug 2019 09:58:53 GMT, Tim+ wrote:

Now I know that in practice it doesn’t matter a jot but every time I mix up
some two-stroke fuel I agonise (very slightly) over whether it’s one part
oil added to 50 parts petrol or one part oil *in* 50 parts petrol/oil mix
(hence one part oil added to 49 parts of petrol)

So, does a 1:50 mixture equal 2% oil in petrol or 1.96%?


As you say, "in practice it doesn’t matter a jot", as long as you've
got a bit of oil in there to provide lubrication. Better to put a
little too much oil in than too little.

I thought it was (un intuitively) the opposite?

The reason being, if you put too much oil in you will still be
metering the same volume of 'fuel' (which is now diluted by oil) and
so you end up running with a lean 'fuel' / air mixture?

Cheers, T i m