Mariner 1981 2 stroke 15hp oil ratio

[Disschord]

Hi can anyone tell me the oil ratio for a 2 stroke 1981 mariner 15hp outboard please

[Fenlander]

I had a Mariner 20hp of that era few years back, a brand new Mariner 8hp around 1984 and still have a Mariner 4hp from the mid 80s and they were all 50:1 so that would be a fair assumption. Around that time a few outboards were going over to 100:1 but in the manual most of them said 50:1 if commercial use... i.e. if you wanted them to last.

[Disschord]

Thanks now I know I am going to sound silly but ratio,s do my head in but if I mix 50/1

Would 1 litre fuel = 2ml oil
5 litres fuel = 10ml oil
10 litres fuel = 20ml

[beerbelly]

there's measurements on the side of the oil bottle cant go wrong

[Wibs]

The way I do it is to convert the fuel into millimetres.......then divide by 50 (or 100 if a 100-1 mix)

This will give you the correct amount of oil to add IN MILLIMETRES

10ltrs of fuel = 10,000 millimetres divide by 50 = 200ml of oil


You had the correct ratio

[Max...]

Leisure use 50:1 most commercials 100:1 - I use 75:1 and made up this chart below but easiest thing is to pre-fill kids pop bottles from a bulk 5L container with the appropriate amount and mark them 5 litre, 10 litre etc and just put one or more in depending what amount 5/10/15/20 etc when you go to the petrol station.

75:1 (1 litre needs 14ml oil)

5 litres needs 70 ml
10 ……..…… 135 ml
15 ……..…… 200 ml
20 ……..…… 270 ml
25 ……..…… 340 ml

50:1 (1 litre needs 20ml oil)

5 litres needs 100 ml
10 ……..…… 200 ml
15 ……..…… 300 ml
20 ……..…… 400 ml
25 ……..…… 500 ml

[Fenlander]

Disschord looking back at my post and the following ones I want to make sure we're not misleading you with mention of 100:1.

I believe it's unlikely your outboard would be a 100:1 model unless you find an original sticker on it or had its instruction book from new that said so.

So go with 50:1 to avoid any damage.

Even if you found concrete evidence that it was designed for 100:1 as it's looking to be over 30yrs old consider this... Max and I have the same outboard as each other (mid 2000s Mercury 15hp) and ours were designed for 100:1 with the engines clearly stickered and/or the information in their manuals. Even so we choose to use the halfway (between leisure and commercial use mixes) 75:1 mix for extra protection.

[Disschord]

Originally Posted by Fenlander

Disschord looking back at my post and the following ones I want to make sure we're not misleading you with mention of 100:1.

I believe it's unlikely your outboard would be a 100:1 model unless you find an original sticker on it or had its instruction book from new that said so.

So go with 50:1 to avoid any damage.

Even if you found concrete evidence that it was designed for 100:1 as it's looking to be over 30yrs old consider this... Max and I have the same outboard as each other (mid 2000s Mercury 15hp) and ours were designed for 100:1 with the engines clearly stickered and/or the information in their manuals. Even so we choose to use the halfway (between leisure and commercial use mixes) 75:1 mix for extra protection.

Many thanks everyone I will go with 50/1 as I would rather my engine didn't sieze.

Your also so helpful thankyou