premix

[Steve@Motowest]

All the major magazines have done this test over and over and the results are always the same. For the typical dirt bike 32 to 1 is the optimal mix ratio.

That's what all the factory teams have used (in modern times), that's what all the magazines use in their test bikes etc... etc....

I know everybody uses something different and everybody is happy and that's all that really matters.

For me, after spending the last 35 years working as a professional technician on cars, trucks, motorcycles, atvs and boats and seeing how oil really works, I choose to use little more oil mixed in my gas and that's what makes me happy.

And here's something else I do.... I even use premix in my 4-stroke machines!

[stay_upright]

Originally Posted by Eric K

I run 38:1.

Why? More oil = better ring sealing and less wear.

My 2 data points...

Top ring end gap increased 0.006" in 91 hours at 50:1

Top ring end gap increased 0.001" in 49 hours at 38:1

This data was with AmsOil Interceptor. Your mileage may vary.

Thanks for the info - very interesting

[stay_upright]

Originally Posted by Steve@Motowest

For the typical dirt bike 32 to 1 is the optimal mix ratio.

Is that due to wear or power or both - if it's wear are results similar to Erik's observations?

[stay_upright]

Originally Posted by Steve@Motowest

And here's something else I do.... I even use premix in my 4-stroke machines!

I can beat that - I put it in the bath at 30:1 and if I wear out before I'm 140 years old I'm asking for a refund

[Steve@Motowest]

Originally Posted by stay_upright

Is that due to wear or power or both - if it's wear are results similar to Erik's observations?

We're not so concerned about wear, we replace parts before they wear out. What we are concerned about is getting more power and not having a catastrophic engine failure from inadequate lubrication during abnormal conditions. It's long story but one time we were able to continue on for more than 3 hours and finish a race with a dry cooling system. That was an extreme oil test.

[widebear]

Originally Posted by Eric K

I run 38:1.

Why? More oil = better ring sealing and less wear.

My 2 data points...

Top ring end gap increased 0.006" in 91 hours at 50:1

Top ring end gap increased 0.001" in 49 hours at 38:1

This data was with AmsOil Interceptor. Your mileage may vary.

Eric I cant say that I agree with you on this point of more oil is better, reason being.I have allways used amsoil @100-1. Last year I did a leak down test on a mc-250 with over 100 hours on it . The test showed 100% ring sealing when I pulled the engine apart, the piston,a wiseco was showing enough wear but very little blowby on the skirt to warrant replacement. My Point is,I believe enough oil to get the job done is enough oil to get the job done. If the part has exhausted its duty cycle and it's time for replacement , using more oil exept in a pure racing enviroment becomes a purely academic exercise and probably wont change things beyond a very neglidgable degree.

[Eric K]

Originally Posted by widebear

Eric I cant say that I agree with you on this point of more oil is better, reason being.I have allways used amsoil @100-1. Last year I did a leak down test on a mc-250 with over 100 hours on it . The test showed 100% ring sealing when I pulled the engine apart, the piston,a wiseco was showing enough wear but very little blowby on the skirt to warrant replacement. My Point is,I believe enough oil to get the job done is enough oil to get the job done. If the part has exhausted its duty cycle and it's time for replacement , using more oil exept in a pure racing enviroment becomes a purely academic exercise and probably wont change things beyond a very neglidgable degree.

There are many, many beliefs and opinions on oil.

My interest is in objective wear data (part measurements) comparing different pre-mix levels. I have yet to see any objective part wear measurement data, so that is why I measured a few points. The few data points showed more oil = significantly lower part wear rate. I recognize that in an ideal comparison the hours would be equal.

Perhaps there is other objective part wear measurement data available comparing different premix ratios. If so, I would be interested in seeing it.

[iancp5]

Eric K,

Well you have given food for thought even if your test doesn't bear scientific scrutiny you have actually measured something as opposed to just going by subjective feeling.

The manufacturers must've done or commissioned a proper study and it would be good to see one but I can understand their reluctance to publish it. In these days of reducing emissions they wouldn't want to put out data that made us all go out and increase emissions. Probably quite happy selling more spares too. If I could significantly increase my engine life I would use more oil but conversely I hate riding in other peoples blue clouds!

[blitz11]

There is an engineering study done by Maxima which supports Steve and Erik K's observations about oil mix. You can find it at
http://www.maximausa.com/technical/oilmigration.html

The short story is

Maxima Recommends: Oil/gas ratio must vary according to anticipated use:

SIZE || Recreational || MotoCross / Enduro / X-Country || Road Racing / Flat Track / TT
50 - 125cc 50-60:1 || 25-32:1 ||20-25:1
125 - 250cc ||50-60:1 ||32-40:1 ||20-32:1
250cc + 50-60:1 || 40:1 || 25-32:1

It appears to be a reasonable study.

Thanks.

blitz

[rpduc]