I never noticed until last week when my car was faster than its ever been. When I got home I realized I forgot to add the premix when I filled up. When I finished that tank. I filled up again and added the premix. The power was back to normal. Then yesterday my memory failed me again and I forgot the premix. The car then turned into a little street monster. It has power past 8K in 1st and 2nd gear. Then again I'm only running 5.5psi with the Haltech so there is no time for the boost to drop off.

Anyway,
I did a search, but it was just x:x ratio and I didn't understand when it comes to numbers my brain shuts down.

The auto parts store has three sizes of 2 stroke. A full quart, 1/2 quart, and a mini. I've been using a 1/2 quart for every fill up. Is this too much?

Then I was reading up on an Australian rotary forum and they were talking about how more people don't run premix and don't have problems. Then I was thinking about how the OMP just drips in the chamber and isn't that oil instantly burned upon entry? So now I'm really confused.

 

technically it's a tradeoff, the less oil you mix with the fuel the more power you will get but at a cost, the cost is added wear and heat.

for example, if you forget to add 2 stroke oil to a 2 stroke weed eater or motocross bike for examples, they will build more and more power up until the engine siezes. why? because of thermal expansion and metal bonding, metal bonding does create a better seal and so does tighter tolerances however this is not good for wear and as it heats up it seals better but creates more heat sort of like a thermal melt down that cannot be stopped until it expands enough to sieze or melt the metals inside or detonate and explode.

rotaries however are different than piston engines, there is a fair amount of room to expand and the rotors are cast iron so they are very resilient to thermal expansion. the apex seals however are not made of such a durable material, they are susceptable to heat and friction, added wear = less compression and added heat = warped seals which also means less compression. you see where i am going with this so basically it's up to you if you want to take a chance of running it without lubrication.

you probably could supplement 2 stroke oil with lead or lead substitute though.

 

The premix I get recommends 1/2oz. per gallon. 1/2 quart (16oz) per 12 gallons is almost triple that amount. To help you with ratios: There are 128 oz. in a gallon. If you fillup 12 gallons that's about 1500oz. There are 32oz. in a quart. There are 4 quarts in a gallon, or about 50 quarts (actually 48) in 12 gallons.

The purpose of the OMP is to lubricate the engine's internals. The oil is not instantly burnt, but it is burnt eventually. I use Idemitsu Rotary Premix from Mazdatrix. It was $3.50 a quart if I remember correctly ($42 for 12 qts.). It claims to improve internal lubrication for better sealing and seal life. I have not noticed a significant difference in power. I have not disabled my OMP.

Royal Purple also sells a two cycle engine oil that it recommends for use in rotaries (and in two cycle engines, of course).

 

yeah, a half quart is definitely way too much.

 

I too was always under the impression that 1oz/gallon was about the proper ratio of oil/gas... which would be just about 1/2 quart/tank.... for S5 anyway, right?

 

thanks Karak, that was very informative. I should have read up on what 2-stroke oil was actually used for.

thanks ericgaru for helping me out with the math. $3.50 is pretty expensive. Higher price = better oil? I figured it all comes from the same oil plant then different companies add different additives which might add to the power loss.

Bigretardhead, that is what I figured too. I'll try 1/4 quart on the next fill up.

 

yeah. I always do 250mL to 30L of gas. so 125:1. always how I have done it

 

i didn't realize you still have a functional OMP, anything over .5 ounces per gallon of fuel with the OMP functional is too much. 1 ounce per gallon of fuel is what people who have no OMP use.

 

The Idemitsu premix is a synthetic designed specifical for rotaries (Idemitsu synthetic motor oil and premix goes into Mazda race cars and I believe it is the factory fill in some countries). That means it has less friction, has better wear protection, lubricates longer before burning away, and keeps the engine & fuel injectors free from deposit build-up. At $3.50 per quart, it's still only $0.65 per 12 gallons of gas. If it saves you even 1/3 mpg (though it probably won't), you'll break even.

I wouldn't trust common 2-cycle engine oil myself. At least get a good brand that claims to keep the engine clean of deposits (it means they add good detergents). And make sure it is API-TC certified, or at the very least TCW3 certified (which isn't enough for extreme conditions, btw, but it's something).

 

and TCW-3 certified...

 

lol, whatever helps you sleep at night..

i use Castrol GTX and the crappo 2 stroke oil from wal mart in my 300+RWHP daily driver.

 

Yup, Walmart gallon special... lol same price as a quart of the high end mix you're using.

 

Castrol GTX is good.

Bad 2 stroke oil will leave deposits. Under extreme conditions you'll get increased wear. You'll lose gas mileage and performance in the long run, and your engine won't last as long. Your fuel injectors will clog earlier too. It's just premix, so I doubt it'll hurt too much unless you disabled your OMP. And in the short run I'm sure it's perfectly fine. A synthetic will give better performance. Though I imagine the gains from using any premix are small.

 

who told you this?

i tore down my motor after 24k miles of using the same exact oils i mentioned and i wiped the rotors of all carbon with nearly no pressure from a shop rag, even the apex seal grooves required no cleaning. the rotor housings looked almost identical to how they did when i assembled the engine the first time. btw, i beat on the motor pretty good, redlining it several times daily and then some.

whoever fed you the garbage that synthetics are the only way to go needs to be shot, personally i'm tired as hell of people talking out their *** about it on the forum.

 

Did you disable your OMP? If not I'm sure the Castrol stuff kept your engine plenty clean. Or maybe the premix is TCW3 certified and contains sufficient detergents? Or maybe you wouldn't have all that carbon with more detergents? I didn't say synthetics were absolutely necessary, but some level of detergents is. And redlining doesn't make the engine dirtier; it helps keep the engine clean. I wouldn't expect much wear after 24k miles regardless.

 

never had an OMP on the engine after i did the initial rebuild, strictly premix is what kept the carbon off the internals.

carbon is still being produced in the same quantities but the premix keeps it from sticking to dry surfaces so it gets blown out the exhaust rather than sticking to the rotors or getting jammed into the grooves.

 

How much carbon buildup was there? Any kind of certification on the premix you used?

It is the oil's detergents that keep the deposits from building up. The purpose of the base oil is mainly just to lubricate. That's why Castrol GTX is nice. Good detergent package.

Personally I go with synthetic premix because $0.65 per 12 gallon tank doesn't seem like much to me. I'd find a decent 2-cycle dino oil if it wasn't cheap.

 

it is the TCW3 certified stuff made for outboards that they sell at walmart in the 1 gallon containers for $6/gallon.

there literally was no carbon buildup at all as i said, i could have sprayed the rotors with carb cleaner and they would have been just as clean as they were when i put the engine together 24k miles prior, all that was on the rotor was a thin oily film that was slightly dirty with carbon so the rotors were almost a hazey brown color that wiped off easily.

i don't always run the cheap stuff though, if i plan on running at an autocross for the day or at the track i will treat the motor to a dose of some synthetic high performance 2 stroke oil that i normally run in my dirt bike since it can handle higher heat better for reduced wear under tougher circumstances.

 

Ok, there you go. It's TCW3 certified. The Walmart stuff is good enough for common use.

 

yep but far from synthetics properties, i see people pushing the stuff daily to people who can barely afford to replace drive belts on their car and why? to supposedly protect the engine or breathe new life into an old tired engine.

i'm just tired of people always trying to push that synthetic is better, i have never seen any proof that it is though i will admit there is a little peace of mind when you plan on pushing your car for extended periods of time but not for daily driving use, i mean nearly an hours worth of total redline time in one day.

edit: what got me was the "cheap" comment, almost all 2 stroke oils are TCW3 certified these days and it doesn't get any cheaper than the wal mart stuff, heh.

 

FWIW, i use the walmart stuff as well. I run anywhere between 1oz:1gal to 3oz:5 gal. I daily drive it 90 miles. I've never had any problems except finding a good way to get it into my gas tank and trying to explain to NJ gas station employees that I have to put blue oil in my tank or my car will explode.

 

as mentioned above that is radically too much if your existing MOP os functioning (and actually too much even if it is not).

But I don't think this has been covered yet in this thread:

Remember pre-mix also lowers the Octane rating, so too much pre-mix and you will have knock and pre-ignition, which will lower power.

If you have an existing running factory MOP, then no more than 6 oz per S4 gas tank full.

And I too use the walmart two stoke almost exclusivly with not problems

 

By how much?

 

depends on how much you use and what your timing is set at and plug temp.

when I am running lean on my non turbo motor with advanced timing, 8 oz in a tank is enough to start getting detonation.

But drop to 6 oz, or switch to a cooler spark plug, or crank back the timing a couple of degrees and it is fine.

 

Here Here!!!

Ive noticed that after switching from regular 2cycle to Marine grade TCW-3, in my 87 N/A, It stoped smoking in the morning, ive noticed that non TCW3 stuff causes a bit of carbon buildup, usaly when I shut it down... I duno if it hurt anything, but it makes me feel better. Also iirc the tcw3 stuff has Anti-Geling stuff, i think it fights aginst it geting cloged to badly in your Fuel Filter. the stuff I use is like $1.50 at wally world...

Ill try and find where i saw that the TCW3 was the best... you guys think that the Idmatsu stuff is that much better?