Raptor75

Has anyone here seen the inside of a Rotary after it has been running synthetic for more then 30K? If so what was its condition as opposed to regular oil?

ltrx8

Someone a while ago claimed that the inner walls had strange gummy ***** of **** stuck to it..But I read on and found that synthetic is not much different only cleaner and as such Ive been running Amsoil 5-20 and have noticed less oil consumption.. Why ? Not sure but this could be why Mazda may warn against using synthetic oil.. However as a bit of added insurance I add 1/2 litre of Redline/Amsoil 2 stroke synthetic motor oil.. You can use up to one litre per full tank without a cat if your really hard on it... I have noticed engine noise reduced by amost half and silky smooth operation especially at 6000 rpm-to redline..As for power its hard to say because it just feels better..Definatly no loss.. Sorry to ramble on but I thought it would help to hear this. 2 stroke oil has been used my many as a premix to ensure lubrication in extremes as it is continuously being administered through your fuel.. who knows there may even be benifits to other components such as fuel pump and injector life..

demob05

I've been hearing a lot about 2 stroke oil and its use on Rotaries... what exactly is 2 stroke oil and how does it compare with regular engine oil (4 stroke oil)??

Go48

Two-stroke(cycle) oil is primarily intended for mixing with gasoline in two-cycle piston engines for lubrication and cooling of the engine. Today, it is commonly used in two-cycle motorcycles, chain saws and other engines of that type. Two-cycle oil is usually sold in concentrated form and it is mixed with gasoline at various ratios of gasoline to oil (e.g.,50:1, 20:1, etc.) according to the level of concentration of the oil and the intended application. This oil is not intended for use as general "engine oil". If you are not familiar with the terms 2-cycle and 4-cycle, check out HowStuffWorks.com.

In a rotary engine application, a small amount two-cycle oil can be added to the gasoline in the tank to enhance lubrication/cooling of the engine. It can also be used in much larger amounts to replace the function of the Metering Oil Pump that normally sprays engine oil into the intake area of the car to combine with the air-fuel mixture entering the engine combustion chamber. People who heavily modify their rotary engines sometimes remove the MOP and use two-cycle oil exclusively.

Raptor75

I am planning on moving to synthetic after the 5K mark. Rotary God seems very high on the idea and I feel he is pretty knowledgeable. On the other hand I hear a lot of noise from Mazda about not using it. After reading a great deal I still don't have a clear picture if Mazda is saying this because it is an unknown for them or if they have really learned some negative facts about it. I feel the only real way to find out is to hear it from the horses mouth, I need to hear from someone who has run this oil and then seen what the inside of the engine looks like after an extended period of use.

demob05

Makes sense.. read some more detail about this in another thread. So basically, the ideal situation is converting the MOP with a 2 stroke oil resevoir exclusively for the combustion chamber, to burn more effectively, while using, say high quality synthetic oil (that doesn't burn easily) in the regular crankcase for lubrication and cooling purposes. BTW, in th rotary engine, which parts (moving or non-moving) use the engine oil only for lubrication??

Go48

Well let's see. Referring to the attached image, the eccentric shaft bearings, rotor bearings, stationary gears and the internal rotor gears that mesh with the stationary gears would be the main components benefitting from oil inside the engine. There may be other components as well that use the oil for cooling and lubrication, but those are the main components.

demob05

thanks for the pics. Didn't know before about the ways these other components worked. In this case, is the same MOP system handling the oil delivery to both the housing/combustion chamber AND also cooling/lubricating these other gears & parts??

yiksing

Someone posted these a while ago, so synthetic or not is still...

Go48

No. There is a separate oil pump for lubrication of those internal engine components.

rotarygod

I've rebuilt engines that I've used synthetic in. I haven't had any problems. I haven't rebuilt an engine that only had synthetic in it over it's life. They were all engines that were switched to it later. You definitely don't see more carbon with synthetic.

yiksing

At what mileage was it switched over?
How far did it went before rebuilt necessary?
How were these engines driven?

rotarygod

I am extremely hard on my engines. They are in sports cars. They need to be driven like they are. You'll do more harm to an engine if you only ever baby it everywhere. This is how carbon builds up. I easily hit redline at full power every time the car goes out. I've never actually needed a rebuild except for 1 engine and it actually still ran fairly well. That one had a spark plug ceramic element break off and fall through the combustion chamber. Left some nice score marks inside the engine on 1 rotor. I bought that car at 63,000 miles, switched it to synthetic at somewhere around 90K and then rebuilt it after the plug incident at 136K. The only thing not usable in that engine was the rotor housings. Parts of that engine went into an another one.

I had a turbo engine that switched to it at 30K. I don't have that engine anymore but it is over 100K now with the owner running on synthetic. No problems.

My current rotary has an engine that I rebuilt only less than 5K ago. It is running on synthetic now but wasn't before the rebuild. That engine didn't need rebuilding. I just wanted to port it. The original owner of that car never drove it hard and just did regular oil changes every 3000 miles. That engine had tons of carbon buildup in it. One of the auxiliary ports was stuck closed from it. When you look in the exhaust ports of that engine now (I have taken off the header and peeked in there), there still isn't any carbon. It's only been a few thousand miles though but I don't suspect there will be any based on what oils I use and how hard I drive.

I know many people that do use and have used synthetics in rotaries. I've never seen one fail due to it. The only rotary failures I've ever seen were from bad tuning in forced inducted applications. I have seen carbon break off inside an engine and crack an apex seal. That engine wasn't using synthetics. Would it have been impossible for this to happen with synthetics? No necessarily. You get carbon through fuel too. It would have been less likely to happen though.

Synthetics are better lubricants that tolerate breakdown better and burn cleaner with less carbon buildup. I'd be scared to use a nonsynthetic in an engine. That would make no sense.

PeteC

You know the reason they went to pumps on 2 stroke motorcycles (one among many anyway) was because the metering pump varies the amount of oil based on the rpm of the motor. Pre-mix two strokes have a tendency to "load up" at idle or part throttle because the oil ratio used is mixed for high rpm (where it needs more oil) to protect the motor. Leads to plug fouling, oily exhaust, smoky exhaust etc etc.

Not sure if the Mazda MOP adjusts for rpm but I can't see how it wouldn't.

rotarygod

The Mazda MOP adjusts for both load and rpm. Premixing is only mixed for the worst case scenario.

nycgps

iTrader: (1)

I've been using Full Synthentic since 500 miles. That was my very first oil change.

I did an oil change once at the dealership, not sure what kind of oil they used since I forgot to ask. but ahh.

I think I changed like 7 times so far and all Synthentic. No problems yet.

Im going to change my oil again in maybe 2-3 weeks from now, of course, Full Syenthic again. My engine has 12K miles on it.

Will see what happens

Raptor75

From all I've researched I tend to agree with you, I'm just curious what has Mazda so spooked on these oils. I wish they would give a little more reasoning when they take a stance if they even did take a stance here.

QBallz

I believe the old seals they used to use in the earlier RX7's would swell with the additive packages in synthetics and wear away extrmely fast.

Since then I believe they use new seals which aren't affected by this, however the stigma still exists.

Fanman

Royal Purple 5W-30 for me.