about engine oil ratios

[Deleted member 12676]

I just finished investigating this topic on the net and now my view on oil ratios has changed a bit.
Usually people want to know how little synthetic oil they can get away with using, whereas the correct question to ask is what is the optimum ratio for maximum power and engine longevity. There have been two series of tests that I know about studying oil ratios. Both came up with the same "best" oil ratio irrespective of whether or not it is mineral oil or synthetic oil. But then another study using the same ratio for the two types of oil found that there was less engine wear using the synthetic oil. That is the basis for people using less of synthetic oil than mineral oil which makes sense. Only question I now have is if thin oil ratios have been an important factor, along with high compression ratio, for the chrome cylinder plating flaking off. I've always had that problem although I kept my engines from having a high compression ratio. But I always used a synthetic oil at a higher ratio than the normal 20:1 of mineral oil. I don't remember exactly the ratio, anywhere between 30:1 and 40:1. Any way the best parts of the internet pages I read on the subject are at www.dragonfly75.com/motorbike/oil.html

 

[Frankenstein]

Could you also post footnotes at least briefing your findings on here too? Many people would prefer not to go to a separate web page (even right now I'm not feeling like sorting through your website to get all the stuff you're saying,) overall you'd benefit the community better if you hit all the high points here and maybe tossed in links for the especially curious. I trust your word for the most part but the method of the delivery can be beefed up a little. At least then it can get people talking and maybe even get stickied, further helping people who really need the help.

 

[Deleted member 12676]

My Recap:
1) Higher RPM requires more oil.
2) Don't rely on what the label says about the oil being full or semi-synthetic. Each brand has their own ratios of synthetic substances put in their oils. The more an oil is fully synthetic, the better the protection but you may not know until after tearing down the engine.
3) Oil residue at the bottom of the crank may be a good gauge showing if you need more or less oil. 1/8" deep is just about right.
4) Castor oil offers the best protection for high performance air cooled engines.

My recent story: My air cooled 100cc revs up to 9500 RPM. It has a steel cylinder sleeve. I was using "semi-synthetic" oil at 25:1 and the cylinder wore down prematurely so that there was much piston rattle. So I had it bored and put new piston/rings in it and ran it at 22:1. It's smoking more than I like but so far, so good.

 

[Deleted member 12676]

I used to think that it was just a waste of oil to use more oil than a 30:1 ratio for synthetic. But I just got a bottle of Maxima Super M synthetic and it says to mix at 20:1 to 50:1.
Why would they even list 20:1 if the common belief that 20:1 is only for regular mineral oil?
It's because 20:1 gives the best protection and the best power no matter what type oil you use.
Synthetic 20:1 gives the ultimate protection.
So when someone asks what oil ratio they should use, the correct answer is not any set ratio based on what type oil they are using, but a return question asking if they want the best protection and power or do they want to spend the least amount of money.

 

[bikejock]

I'm getting my first PK80 2 stroke kit next week & I've been researching good oil gas mixture ratios. Seems like for the break-in period 8 ounces per gallon is recomended then after the first 2 gallons although bikeberry says first two tanks for some reason making it a little confusing. (honestly who mixes in the tank?) A common kit tank is usualy a 1.5 liter which is I think 1/2 of a gallon seeing a gallon is 3 to 3.5 liters. But after the break-in period a 4 ounces per gallon mix seems to be recommended. I'm using a 2.5 gallon (plan to just fill it with 2 gallons of premium) gas container for mixing & want to be sure I'm getting the right oil mix so I don't ruin the engine durring the first ride. Plan to use Royal Purple full synthetic oil.

 

[MotoWolfy]

Thanks everyone for helping me get cleared up on the oil/gas ratios. One thing I noticed no one seems to mention is the actual gas type. So I am going to ask here and not sure if it should be a new thread.

Would it not be better to use straight petrol with no ethanol added? My experiences with small engines, be they 2 stroke or 4 cycle is that ethanol is a nutorious for causing corrosion and pre mature wear in small engines due to how it tends to keep moisture in the fuel.

Any thoughts?

 

[Steve Best]

Excellent post and info on your website Jag!
40 years of biking I have come to embrace the same conclusions.
I did use these engines to play with oils and ratios to "relearn" what I thought I knew.
Here iare the conclusions I came to:

Compression, rpm, heat and max power are hard on chrome cylinders.
More than 40:1 oil of any type does not protect chrome very well at high rpm and pressure.
Under 20:1 of any oil seems to hinder power, makes starting hard, and fouls plugs. Weak ignition may be a factor.
Castor oil protects chrome the best, synthetic next and mineral oil almost as well with its quality being important.
Synthetic leaves the least ash but tends to drip out of the exhaust, castor leaves lots of carbon.
If you are riding to save money, good quality mineral oil at 32:1 will certainly do that do.
If you are looking for maximum power and rpm, I'd suggest castor at 24:1, otherwise synthetic at the same ratio.
Castor seems to build up a film on parts that seals and protects, synthetic seems to strip deposits clean. Don't mix them!

Pretty much the same.

Good info Jag, great page!

How do you "manually remove the ethanol"?

 

[Frankenstein]

How do you "manually remove the ethanol"?

Well for starters I take the cap off the bottle, I have a hard time remembering what happens after that though...

 

[MotoWolfy]

Excellent post and info on your website Jag!
40 years of biking I have come to embrace the same conclusions.
I did use these engines to play with oils and ratios to "relearn" what I thought I knew.
Here iare the conclusions I came to:

Compression, rpm, heat and max power are hard on chrome cylinders.
More than 40:1 oil of any type does not protect chrome very well at high rpm and pressure.
Under 20:1 of any oil seems to hinder power, makes starting hard, and fouls plugs. Weak ignition may be a factor.
Castor oil protects chrome the best, synthetic next and mineral oil almost as well with its quality being important.
Synthetic leaves the least ash but tends to drip out of the exhaust, castor leaves lots of carbon.
If you are riding to save money, good quality mineral oil at 32:1 will certainly do that do.
If you are looking for maximum power and rpm, I'd suggest castor at 24:1, otherwise synthetic at the same ratio.
Castor seems to build up a film on parts that seals and protects, synthetic seems to strip deposits clean. Don't mix them!

Pretty much the same.

Good info Jag, great page!

How do you "manually remove the ethanol"?

I have no idea how to manually remove ethanol, here in Washigton state, we have gas stations that sell ethanol free fuel. 2 of my acquaintances, one of whom has been small engine repair for close to 40 years, say that if ethanol free is not possible, the highest octane available is next choice, even then they recommend a product available at most lawn equipment retailers to add to fuel. I beleive it is made by "Mechanic in a bottle". I do know fuel with ethanol left to stagnate will have water settle at the bottom. Ethanol free gas also stores better with a longer shelf life, about 5 months, and using Briggs and Stratton fuel saver can see it last upto a year, even mixed fuel.

 

[Frankenstein]

I have no idea how to manually remove ethanol, here in Washigton state, we have gas stations that sell ethanol free fuel. 2 of my acquaintances, one of whom has been small engine repair for close to 40 years, say that if ethanol free is not possible, the highest octane available is next choice, even then they recommend a product available at most lawn equipment retailers to add to fuel. I beleive it is made by "Mechanic in a bottle". I do know fuel with ethanol left to stagnate will have water settle at the bottom. Ethanol free gas also stores better with a longer shelf life, about 5 months, and using Briggs and Stratton fuel saver can see it last upto a year, even mixed fuel.

If you're storing gas for a year then you must not being doing anything at all with your life....