Hi, I understand this question has been asked a million times; however most of the premixing info online seems to be in US gallons and units. I am looking for a clear answer for us brits. What ratio (with an OMP) should I premix oil:fuel in litres/ml etc...? Also, what oil would you recommend for premixing for my 1981 Mazda rx7 fb in the cold British climate. I've attached a pic of my fb for those interested. Cheers

 

My engine builder told me 200:1
that was a 450rwhp turbo build with 12a mechanical omp.
edit: thats literally 200:1 as in say, 100ml per 20liters, not 200 turnips per parsnip or whatever our ameribros use.
its pretty arbitrary though and varies from person to person. Possibly not even necessary

 

every builder will have their recommendations as well as seal manufacturers have theirs.

OEM seals with good working OMP, NA or stock level boost, street driving, may not need any premix but most recommend 250:1 as a good daily preventive maintenance level

all the way to 40-50:1 for aftermarket seals, high boost and racing

That's for petrol. Ethanol, Meth or other fuels have different requirements

 

dang it this is America we're not going to use vegetables! its 37/74ths!

Pee Jay posted this article about premix many many years ago, and its a good read

 

Countries that don’t use the decimal system.

Fellow Brit here, now living in California. Not only do we work in gallons rather than liters here… the USA gallons are not the same as British gallons. Maybe why I ended up working on mountain bikes and Japanese cars which are both metric. Except for tires, or should that be tyres?

This may also be useful… USA to English translation from my Haynes RX7 manual.

 

there's conversion calculators all over the interwebs that will convert gallons to litres.