Synthetic Oil Bad?

[DevoutWankelist]

I saw some people on another forum arguing over whether synthetic oil was bad for a rotary engine or not, anyone know what the truth is?
Also I saw on another thread here that premixing 2 cycle oil in your gas was healthy for rotary engines as well, just curious.
One more question, can an exhaust system be too free flowing?

[Soyo]

you can use syntheticoils for the most part and yes an exhaust can be too free flowing... too big=not enough back pressure

[DevoutWankelist]

Yeah I know about not enough back pressure, but what is the exact function of back pressure and what is practical for a 91 n/a rx7?
And what about synthetic oils leaving some sort or residual buildup in the rotor housing?

[J-Rat]

DO NOT USE SYNTHETICS! These have been proven detrimental to rotaries (since the burn oil). Use CASTROL!

Pre-mixing is an alternative to using the OMP, and it has been proven to more evenly distribute the oil. On your 91, if you remove your OMP, your ECU goes into "limp mode", how to defeat that, I dont know.

Jarrett

[DevoutWankelist]

Thanks J-Rat, unfortunately the car has had synthetic from the previous owner, so would there be any problem with just switching over to regular?
And what specific kind of oil from castrol, again thanks.

[J-Rat]

I personally run Castrol 20-50 (GTX). Depending on the temps in your area, you might want to adjust to a different viscosity.

Jarrett

[Steel]

bah. rip out the stupid OMP, because it's probably on it's last legs anyway, run premix with your gas, and put mobil1 in your engine. Then you will have a happy rotary

*edit* oh wait.. you have an S5.. well that sucks. Guess you gotta stick with the OMP until you get an aftermarket ECU.
Man. I like S4's so much better than S5's.

[Soyo]

yea well I use castrol gtx 10 W30

Using Synthetic Oils in Rotary Engines


--------------------------------------------------------------------------------

This has got to be one of the most frequently asked questions ever!

Here is our answer:
The Rotary engine has an oil injection system that injects small amounts of oil into either the intake tract, carb, or rotor housing (depending on year/model). This is needed to lubricate the various internal seals and surfaces.

The injected oil MUST BURN, and must burn clean. The root answer to the question is that not ALL synthetic oils burn, and not ALLof them burn clean.
The ones that do not burn accumulate until they foul the spark plugs.
The ones that do not burn clean can leave residues of various substances (like ash? plastic? non-organic sand?) that accumulate until the spark plugs foul, or a seal sticks -- could be apex seal, side seal, corner seal, or oil control ring. The normal consequence of a stuck seal is an engine tear down.

In the many years we have been involved in rotary engines, we have NEVER had a problem with GOOD petroleum based oils. They work fine! They are less expensive than synthetics. (We use Castrol 20-50 GTX). They burn clean, etc. etc.

The problem with answering the original question is that it is NOT a simple yes or no. We DO simplify it to a "NO", but that is because we do NOT know whether the specific brand of synthetic the customer has in mind will work. AND, if it does not work, how long will it be before the damage shows up, and how bad will the damage be? Maybe it will take 10,000 miles, maybe 50,000 miles?? Maybe the engine will fail due to something unrelated to the oil, and there won't be enough left to determine why the failure happened.

WE are not willing to take that gamble, are you ?

Then, take a minute to think of WHY you want to use a synthetic. If a rotary engine (properly maintained, oil changes at 3K intervals, etc.) can still be running fine at over 200,000 miles, the engine does not need any more cooling, the gas milage will not be any better, etc. etc. WHY do you want to spend more $$ and gamble on engine and/or spark plug damage? (If you are into the fossil fuel thing, pollution, depleting our resources, etc. then you should not be driving ANY car!)

We are not chemists, and we do not have the time, $$'s, nor inclination to do 100K mile tests of various synthetics in rotary engines.

We DO use synthetics in the transmissions and rear ends - it works fine.

Anyway - that is the MAZDATRIX version of the synthetic question.

this is all straight from www.mazdatrix.com

so some your can use, just that you don't really know which not to, and there isn't really a reason to anyways

[dayna240sx]

I use valvoline 20w-50

[dayna240sx]

Originally Posted by Steel

*edit* oh wait.. you have an S5.. well that sucks. Guess you gotta stick with the OMP until you get an aftermarket ECU.
Man. I like S4's so much better than S5's.

Last I checked Ted made a Series 5 electric OMP cover plate.

seriously though, running Pre-mix is a PITA....

I had to run pre-mix in my 1st Gen race car... I always kept a 5gal kerosene tank in the back (used kerosene because it was blue, and different than red... and i labeled it "pre-mix"

HAd it down to a science, I kept a small metal measureing cup tied to the handle to the tank... I needed to get gas at 5gal intervals..

NOT good for a daily Driver... or when you drive your car to the track...

[DevoutWankelist]

Thats all ok, if all goes well it wont be a problem at all, since I found an immaculate 88 t2 for sale a mile from my house, I will own that car, it might not be easy though as I got laid off last week, BAD Fing TIMING, buuuuuuuttt its got one dent and 127000 miles, other than that, immaculate. Now for the hard part, financing without a job.

[Jims5543]

I daily drive my TII and premix. I have been using synthetic oil in my TII's for over 2 years now. I found the engine to run cooler in exteme conditions such as Autocrossing.

Let me make something very clear. I was dead set against premixing. I did not want to be bothered screwing around with oil and making a mess everytime I needed gas. I did everything I could to avoid premixing. It was inevitable after my engine swap and switch to a Motec EMS.

Then I met Kandy the engine builder at Pettit racing.

She showed me 2 rotor housings. One from a car that used the OMP and the other from a car that used premix and no OMP. That convinced me my switch to premix was a smart move.

The OMP housing had a nice shiney band aound the middle where the weep hole is for the OMP. The premix housing was nice and shiney all they across. It was obvious that the premix was doing a much better job at lubricating the housing.

To make my life easier I bought a case of Amsoil premix. (supposidly one of the best premixes out, I am sure there are other opinions on this) You can order it in different sizes. I bought a case of 8 oz. bottles. and mix 6 oz. to a fillup. which is about 10 gallons. If I am racing that weekend I add 8 oz. per tankful. I have since stopped using amsoil, it is awesome premix, if favor of using Pettits Protek premix. I figured if it was designed w/ a rotary in mind it will be better for my car.

I just took my TII of the road and it is at Pettits being streetported. Kandy is going to call me when she has the engine apart. I run Amsoil Racing 20w50 synthetic.

**LOL!** Cameron called from Pettit while I was typing this. His first comment was "You must me running premix in this engine there is hardly any sign of wear" He went on to tell me he was suprised of how good of condition the engine is in being that I race it a lot. They are street porting it now and I should have it back next week. WooWoo!**

[Jims5543]

OOPS!! I stumbled across this wesite today. I found the last couple of lines of this entry to be fascinating. It seem Mazda used Synthetic Oil in its 787B Race car, you know, the one that won the 24 hours of Le Mans. Hmmmm.....

Link to website:
http://www.rotaryaviation.com/rotaryhistory.htm

ROTARY HISTORY 7: THE ONE THAT WON IN '91
Edwin Krampitz,On 23 June 1991 Mazda won the 24-hour Le Mans endurance race with a Category 2 (C2) 787B racer, #55, powered by a 4-rotor R26B--the first and likely last rotary win because of C2 rule changes prohibiting rotaries in 1992. Just to finish Le Mans is an accomplishment--let alone win. The 787B covered 4923.2 km (3059.1 mi) at an average speed of 205.3 kph (127.6 mph), exceeding 320 kph (200 mph) on the main straight. Yet it still had 30.0 liters (7.9 gallons) of fuel left of the maximum 2550 liters (673.6 gal) allotted, giving an impressive 4.6 mpg. Here's a look at this historic engine, emphasizing the DIFFERENCES between the R26B and the 13B whose geometry it's based on.

The R26B develops 700 net bhp (Japanese) at 9000 rpm, its redline, and 449 net lb-ft of torque at 6500 rpm. It's only 39" long and weighs just 396 lb. The R26B has a 3-piece eccentric shaft; the long main shaft has journals for rotors #2 and #3 and tapered extensions for 2 hollow shafts with journals for rotors #1 and #4. Counterweights are used at both ends. To stiffen the engine, aluminum honeycomb is used where needed, including the aluminum oil pan, which is mounted on top. The R26B uses a dry-sump oil system. Tension bolts are anchored throughout the intermediate housings, further increasing stiffness. Engine coolant and oil enter through the center housing.

Rotor and side housings are coated with hot-sprayed chrome-carbide cermet (ceramic in a metallic array) for high-temperature wear resistance. The intake as well as exhaust ports are peripheral. Each rotor housing has 3 spark plugs: a third "far-trailing" plug was added for better fuel economy and power. Rotors were precision cast to a 10.0:1 compression ratio using the lost-wax method to reduce rotating mass. Two-piece silicon nitride ceramic apex seals have, in the words of one summary, "a 'sprinkle' of an ingredient that raises heat conductivity", and they use 2 springs. The R26B has a sophisticated electronic port fuel injection system and telescopically variable intake pipes whose length vary with engine speed to improve airflow.

After winning, this historic engine was taken apart in front of the press. Little performance deterioration had been noted during the grueling race, and the R26B looked nearly new after dismantling. Even Mazda's head office engineer said, "In the case of the rotary engine, damage to the apex seal is the best reference. And as you can see, it's nearly untouched." After measurement, wear on apex seals, rubbing surfaces, and bearings were found to be only 1/3 to 1/2 the upper limits--in Mazda's words, "indicating remarkable durability and reliability". As racer Paul Frere was to say of the win, "A pity Felix Wankel has not lived to see it."

It would be a shame for this racing development to be a technological dead end for the rotary. Am I the only one who sees potential for adapting the R26B and this technology for aviation use? What say you, Mazda?



POSTSCRIPT FOR INTERNET: Because of the collapse in the 1990s of the sanctioning organization that issued the rule changes, Mazda could run a rotary racer similar to the 787B again at Le Mans if it wished. Despite rumors to the contrary, so far it hasn't. You can buy a 90-minute video of the 1991 race showing Mazda's victory.



A special synthetic oil was developed by Idemitsu Kosan Co. just for the Le Mans race. It has a polyalphaolefin base with a detergent inhibitor package and a molybdenum friction reducer. A street version of this oil called "Rotary 1", meeting API specifications, became available in 1996 in 1-liter and 4-liter tins painted like the Le Mans winner. Be warned that it's incredibly expensive: $38 per LITER (1999) or $133 for 4 liters.