Synthetic 2 Stroke Oil Benefits?

[Srt20]

Originally Posted By: Cujet
The issue with two strokes is that once detonation starts, piston seizure is not far behind. The two stroke engine may not need higher octane. Right up until it does.....

The main advantage of a quality two stroke synthetic is to prevent ring sticking, the resulting blowby and premature loss of compression.


Probably detonation:

Absolutely detonation:

Deto: Notice that not only did the crown fail, but the skirts are damaged, especially at the top, from excessive expansion due to, you guessed it, detonation.

Those that say two stroke engines don't need high octane are incorrect. The best thing one can do for two stroke reliability is to use excessive octane coupled with sufficient oil.


To the OP;
This is the only post you need to pay attention too. It has all the correct info.

 

[dlundblad]

Originally Posted By: Srt20
Originally Posted By: Cujet
The issue with two strokes is that once detonation starts, piston seizure is not far behind. The two stroke engine may not need higher octane. Right up until it does.....

The main advantage of a quality two stroke synthetic is to prevent ring sticking, the resulting blowby and premature loss of compression.


Probably detonation:

Absolutely detonation:

Deto: Notice that not only did the crown fail, but the skirts are damaged, especially at the top, from excessive expansion due to, you guessed it, detonation.

Those that say two stroke engines don't need high octane are incorrect. The best thing one can do for two stroke reliability is to use excessive octane coupled with sufficient oil.


To the OP;
This is the only post you need to pay attention too. It has all the correct info.


Thank you. I knew going into it that the high octane fuel wasn't a mistake as others mentioned. First time I had read that here actually.

The majority of my 2 strokes are relatively new, but I do have a few LB's from the 80's and 90's. Not sure what their manual says. (If that matters at all.) I just use the LB 2 stroke oil in these.

 

[tig1]

I have a 14 year old Echo weed wacker that I have used Amsoil Saber oil at 50:1 mixture(what the book calls for) with 87 Oct fuel. Still runs fine. Only time I see a small amount of smoke is on start.

 

[Dave Sherman]

Originally Posted By: boraticus
Originally Posted By: Kamele0N
Originally Posted By: boraticus

It's not a matter of cost. It's a matter of most two cycle engines not designed to run on high octane fuel. Some engine manuals actually warn against using high octane fuel.


Where did you read that nonsense?


Please advise of any two cycle manufacturer that recommends high octane fuel.


The owner's manual for my Echo weed whacker calls for 89 octane minimum. If high octane is supposedly bad for 2-strokes, why is Trufuel pre-mix rated 92 octane?

 

[Rickey]

Originally Posted By: Srt20
Originally Posted By: Cujet
The issue with two strokes is that once detonation starts, piston seizure is not far behind. The two stroke engine may not need higher octane. Right up until it does.....

The main advantage of a quality two stroke synthetic is to prevent ring sticking, the resulting blowby and premature loss of compression.


Probably detonation:

Absolutely detonation:

Deto: Notice that not only did the crown fail, but the skirts are damaged, especially at the top, from excessive expansion due to, you guessed it, detonation.

Those that say two stroke engines don't need high octane are incorrect. The best thing one can do for two stroke reliability is to use excessive octane coupled with sufficient oil.


To the OP;
This is the only post you need to pay attention too. It has all the correct info.


I agree.

Proper oil mix plus more than adequate octane = happy 2 stroke !!!!

 

[Kamele0N]

Originally Posted By: mjk
Originally Posted By: Kamele0N
Originally Posted By: boraticus

It's not a matter of cost. It's a matter of most two cycle engines not designed to run on high octane fuel. Some engine manuals actually warn against using high octane fuel.


Where did you read that nonsense?


Actually, I had a 1977 Evinrude 15 hp. Engines from that era were not designed to run on 92-93 octane. Go Google it.


I had one "donated" Johnson QD15...i think it was from 55? It was used & abused and it was not worth it to repair/salvage....so as a kid I had dismantled it out of the curiousity and put it into the garbage bin

And it construction (internals) was nothing "out of the ordinary" from other 2strokes I have seen...

I can only asume that this octane limit has something to do with a fact that high octane fuel of that time contained lead...and that lead-free fuel (with a lower octane number) was used here because of the ecological orientation

 

[Kamele0N]

Actually it had "deflector pistons" similar to that below for higher compression and better scavenging of the mixture...it will only benifit with the high octane fuel!

 

[Silk]

That looks like a high compression 4 stroke motorcycle piston. This is a 2 stroke delector piston.

US outboard manufacturers hung onto the deflector piston for long after the rest of the world had gone to loop scavenge.

 

[Al]

I own Stihl Products. If you buy a six-pack of their syn oil they double the warranty.

 

[HangFire]

Hole in the piston is most likely bad ignition timing.

High Octane is a very marginal benefit compared to the negative effects of lean burn. You can't out-Octane a lean burning engine. It's going to die anyway.

 

[dblshock]

Ten years on 640:1 TCW-3

 

[dblshock]

 

[dblshock]

 

[4WD]

My wife has been on Diet Coke that long ~ this seems to be working better …

 

[boraticus]

Originally Posted By: HangFire
Hole in the piston is most likely bad ignition timing.

High Octane is a very marginal benefit compared to the negative effects of lean burn. You can't out-Octane a lean burning engine. It's going to die anyway.



Finally someone who gets it.

Improper timing and lean mixture are the main causes of piston failure in two strokes.

I own two moderately tuned 1970's two cycle Yamaha RDs with upgraded programmable electronic ignition, slightly ported, squish band reduced, carbs modified and expansion chambers. They're producing 30% more power than stock and running a bit over 11,000 rpm wide open. Not once have I concerned myself with thoughts of octane requirements. Proper jetting and timing are what matters. Both bikes run very well and are as reliable as any Yamaha should be.

The octane argument is of little value, particularly if timing and fuel mixture are incorrect.

And, by the way, I never use expensive synthetic oil. Modern conventional oil provides all the protection a two cycle engine will need under normal circumstances. If I were racing, maybe then I'd switch to synthetic. Otherwise, no.

 

[Silk]

The lubrication is pretty basic, that's taken care of by a good oil. But 2 stroke oils are now smoke driven, the powers that be want them not to smoke, so we get low smoke oils, and they are usually synthetic.

 

[Rickey]

"Finally someone who gets it."

Not so sure I understand what you mean here.

Really per-ignition caused by insufficient octane can not be ignored as a source of engine damage/failure.

"Not once have I concerned myself with thoughts of octane requirements."

If that statement is taken literally you could run kerosene with the proper 2 cycle oil and have a positive outcome in a 2-stroke engine!!!

Feldercarb!!!

Please explain your bold statement with scientific data to back it up Sir.

Yes I agree that improper timing and lean mixtures ( E10 in early engines ) can damage an engine.

How many weed whackers or chainsaws really have timing issues.

Aren't most ope made in the last 20 years jetted with E10 in mind?

I maintain that synthetic lubricants have superior film strength under adverse operating conditions.

Please notice we are in an OPE area of the forum here, 2 smoke bikes are nice... yes.

Apples to submarines though regarding OPE.

 

[Cujet]

Originally Posted By: HangFire
Hole in the piston is most likely bad ignition timing.

High Octane is a very marginal benefit compared to the negative effects of lean burn. You can't out-Octane a lean burning engine. It's going to die anyway.


I understand what you are trying to say. But "lean" with regard to a standard 14.7 to 1 (stoichiometric) air/fuel mixture is not a problem in most engines. As true lean mixtures tend to combust quite slowly and are often quite a bit cooler. Many engines, two strokes included, run best and make the most power, on an air/fuel mixture that is significantly over rich. The proper AFR (air fuel ratio) for a two stroke is 12.0 to 12.6 to one.

An air fuel ratio that far rich of stoic, (12.3 : 1) strongly suppresses detonation. And allows the use of lower octane fuel.

Conclusion, the two stroke, and in particular air cooled two strokes and high performance two strokes are prone to detonation. Deto is combated via an over rich mixture.

What happens as we move the mixture from the ideal 12.3 : 1, towards 14.7 to 1 (but not beyond) , peak cylinder pressure increases, as does peak combustion temperature. The result is a cascade of temperature and pressure events leading first to detonation, then rapidly to piston overheating, a hole or a seizure.

A technical issue like improper ignition timing, or a spark plug heat range so hot it glows, is NOT the problem in most cases. In most cases it's detonation and sufficient octane can help with this.

 

[boraticus]

Over the years, I've owned probably 30 two cycle engines from OPE to snowmobiles, to modified vintage street bikes to racing dirt bikes and never holed or damaged a piston. Decades of two cycle experience and all of it on regular pump gas. From my personal experience, the octane issue with relatively low compression two strokes is more myth than reality. Lean jetting, bad timing and insufficient lubrication will destroy more two cycle engines than anything else.

 

[Silk]

I've always run 2 strokes on low octane fuel, they generally don't use high octane.