Oil related failure in the Renesis rotary engine

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This is a post-mortem of the RX8 engine that I used do own. The failure was side seals. The failure mechanism was lack of lubrication. Mileage at failure was just under 50K miles. This was an AT vehicle with a 7500 rpm redline. The following are my thoughts on why it happened.

Mazda is balancing emissions with adequate lubrication in the Renesis. It is my opinion, as well as others, that emissions won and lubrication suffered. The motors that are lasting beyond 50K miles are the ST units with 9500 rpm redline. The oiling map is much enriched above 4-5K rpm. Those that run their ST units above 5K regularly are getting more oil to the seals from the oil injection pump. This running above 5K is more difficult for those with the AT.

Mazda placed two oil injection ports in each rotor side plate to lubricate the seals. These are ports, not long slots, so getting oil to all corners of the seals is, in my opinion, the job of fuel. Fuel is the carrier of the lubrication oil, just like in a 2-stroke motorcycle or chain saw motor. The rotary runs very rich, so there is lots of fuel to carry the oil.

The ideal solution to oiling in the rotary is to block off the sump intake to the oil injection pump and supply the oil injection pump with 2-stroke injection oil. This is what racers and those who use the rotary in aviation do.

In my opinion, this is why Mazda recommends “conventional” oil in the Renesis crankcase. “Conventional” oil has more grp I and grp II components. These oils are somewhat miscible in gas, leading to more oil in the far corners of the side seals in the Renesis.

The above is only an opinion on my part, but my own experience follows this reasoning. OCI on this car was no longer than 3K miles. Most of the early OCI’s were on Havoline and Motorcraft 5W20. My motor started to run poorly with two OCI of Royal Purple 5W20 that I used on the advice of “experts” at the RX8Club forum. My motor failed completely with the next OCI of Renewable Lubricants Inc. 5W20 that I used on the advice of another expert. The RP and the RLI are known to resist fuel dilution. I have no question that my motor would have failed anyway, as this is the experience of most of the owners of 2004 RX8’s with automatic transmissions. The use of synthetic oil just hastened its demise IMHO.

Anyone else have theories on this issue?
 
Don't really have a theory of my own, but I am kinda surprised that members of any RX-8 club are endorsing the use of synthetic oils in this engine. Mazda has not-so-quietly spoken against its use, and there are countless people like you that can be used as testimonials to what can happen when you ignore the directive.

Dino oil, checked regularly, and rev the p*ss out of it every chance you get. I know it sounds counterintuitive to the care and maintenance of an engine, but in this case it's true. Maybe the folks with an auto tranny should be manually downshifting and driving around in a lower gear.
 
Its a hard place to be.

Dino is spec'd by Mazda. But the Rotary runs SO HOT and when you do a oil change alot of oil (2+ quarts) of old oil stay in the systems oil coolers.

I ran dino then Royal Purple in my Rx-8. I had a 6speed manual though with the 9500 redline.

I would not blame RoyalPurple so soon. Many Rx8 owners on Rx9club (I am a member) use it with no issues.

The RX8 is a touchy car, with not the best reliability nor warranty. That is why I axed mine only after seven months of ownership.
 
My friend runs a gen2 rx-7 turbo, with 15w-40 HD oil for many years, hard use, track use. With that much fuel and oil mixing I can't imagine runing anything other than very high TBN 40 wt and changing it often. He had way over 150 K kms on his and he only did the apex seals once.

I wonder if this engine would last longer using an oil like this. Sometimes emissions just have to take a back seat in engines such as this.
 
Good replies all around
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This is not a RP or RLI bashing thread. Both oils have many very good UOA's on this site and may be ideal oils in another vehicle.
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Originally Posted By: rg200amp
Its a hard place to be.

Dino is spec'd by Mazda. But the Rotary runs SO HOT and when you do a oil change alot of oil (2+ quarts) of old oil stay in the systems oil coolers.

I ran dino then Royal Purple in my Rx-8. I had a 6speed manual though with the 9500 redline.

I would not blame RoyalPurple so soon. Many Rx8 owners on Rx9club (I am a member) use it with no issues.

The RX8 is a touchy car, with not the best reliability nor warranty. That is why I axed mine only after seven months of ownership.



*** Rx9club should be Rx8club!!
My bad
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Yeah the rotary is an interesting beast. I used to run my '86 on Pennzoil Yellow Bottle, at 177k, I sold it in perfect running order. Who knew me beating the [censored] out of it was good for it? The beauty of the teenage mind in those days....
 
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Currently running Esso XD3 0w30 in my 04 manual.

Using 4oz of Lucas UCL in every tank.

They sell a full PAO Synthetic made specifically for the Renesis in Japan. That and my engine is warrantied for another 3 years and 160,000km by Mazda helps me sleep at night.

The only two things I don't like about the rotary are the debates about: thin vs. thick, dino vs. syn
 
Originally Posted By: Smokescreen
My friend runs a gen2 rx-7 turbo, with 15w-40 HD oil for many years, hard use, track use. With that much fuel and oil mixing I can't imagine runing anything other than very high TBN 40 wt and changing it often. He had way over 150 K kms on his and he only did the apex seals once.

I wonder if this engine would last longer using an oil like this. Sometimes emissions just have to take a back seat in engines such as this.


You might be on to something. This might be one engine that requires more than 5w20. I wonder what oil is spec'd in Australia? Are they suffering from the same engine failures?
 
I agree that the OP's Renesis was done-in by a lack of lubrication and I think it was caused by too low viscosity combined with high oil temp.

The first modification I made to my 2007 Automatic RX-8 was to add an engine oil temp gauge. During my first summer while commuting in the Phoenix bumper-to-bumper highway crawl (20 to 25 mph) I saw engine oil temps quickly rise to 230*F to 240* F
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until I had a chance to get my road speed up to at least 40 mph - then the temp slowly dropped back to about 200*. And my car has the second engine oil cooler Mazda started installing on U.S. automatic RX-8s after the 2005 models!
So I installed a 160 cfm muffin fan behind each oil cooler controlled by a 200*F thermo switch. Now temps typically stay below 210*F and one worst case really hot and dry day near 220.

Since buying this car in December 2007 I've kept two habits to deal with the Renesis' idiosyncrasies: 3000 mile OCI of Rotella 5w-40 synthetic and 1oz of Marvel Mystery Oil per gallon of fuel. Since the Rotella is a Group III, this puts me comfortably in the middle ground of the synthetic vs. mineral oil controversy and the MMO fuel additive takes care of any possibility of overly lean oil metering settings. Also, these two in combination should help keep the ports and related valves clear of carbon while the higher than recommended viscosity Rotella should handle the engine's tendency to put both heat and fuel into the oil.

Should be a recipe for a long-life Renesis, I hope.
 
The opinion varies. But I think the consensus is that PAO, and certainly GRIII, synthetic can be used in the newer rotaries...

Mobil1's older site also stated that 15W-50 M1 would work alright in the rotary as well...
 
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I own an manual 2005 RX-8 and have not put synthetic in my car. I figure its not worth the potential issues. I did add FP60 and now FP Plus in my car. I also try to rev the car near redline at least once everytime I drive it to clean out the carbon crud.

I am on RX8club.com. It is a wealth of information, but in the end you have to make your own decision. For example, owners were putting in synthetic GL-5 for transmission fluid like RP MaxGear and then found out they needed new transmissions. It seems like GL-4 was the way to go as the GL-5 ate away at metals in the transmission. However, it really in the end was Mazdas fault as they initially said in the manual GL-5 was okay then retracted it and said GL-4 only in later manuals. Hmmm. Wonder why.
 
I bought my son a '04 RX8 manual a couple of months ago.

It's got Motocraft 5W-20 synthetic blend in it right now.

I have also been following the oil discussion on the RX8 forum.

I believe that a quality conventional motor oil in 5W-30 is likely the best choice for the car. The 5W-20 is a fuel saving ploy that has probably cost some RX8 engines.

I think 3000 mile change intervals are important due to fuel dilution.

A group III synthetic should work fine in the car but with my expected change frequency it may be a waste.

Some 2 cycle oil might be beneficial but at the cost of plug fouling in richer mixes.

My plan for his car is a 5W-30 YBP at 3000 miles. I may sneak some clean burning 2 cycle oil (not synthetic) in the gas at 3-4 ounces per fill up.

Mazda upped the warranty to 100,000 miles on these engines. I hope you are getting a factory reman for free.
 
I think its really sad that a wonderful, incredible engine like the rotary, has managed to fall into the hands of some really really REALLY stupid and dumb people who haven't a clue as to the capabilities or needs of a rotary engine.

Now, Im not pointing any fingers here.. You have to look yourself in the mirror and answer the question of whether you knew or know and can appreciate what a rotary engine is.

When you have a specialty motor like the Rotary, why the [censored] do you ignore what the manufacturer says to use in it?? WHY?? What the [censored] is wrong with following the directions? And get this.. These are the same people who [censored] at Mazda about flooding issues, wear issues etc...

Its called, KNOW WHAT YOU ARE DRIVING!! if you don't want to or can't take the time to understand then please, do us all rotary fans a favor and sell your car, and get a nice safe Toyota. trust me, you won't be missed.

And sorry, the only reason why Mazda put an automatic in the rotary was because Ford made them do it. The rotary was NEVER made for a wimpy automatic. 7500 rpm redline for an engine that is easily capable of 13K is a joke.


Synthetic in the rotary is waste, and its not reccommended so don't do it ok???

The engine burns oil as part of its routine and you will be constantly replenishing it anyways. The oil needs to be able to burn CLEANLY AND THOROUGHLY which synthetic is designed NOT to do just that. There is really no low temp flow concerns either like a piston and rod/ camshaft motor.. There are no valves, no rockers, no rods, no camshaft and no pistons.

the new renesis motor has a 3rd injector. This should help.
 
I saw a Renesis dead at 130K miles. He got PZ yellow bottle 5w30 or 10w30 and had it changed every 3000 miles.

I will never buy a rotary engine.

I also met plenty of people with rebuilt 13B-REW engines, they have short lives too.

I have heard of people using 2 cycle oil in the gas, modifying the oil injection system, and a few other things to try to get more life.

I wouldn't want any engine in a daily driver that requires stuff other than pump gas, regular oil changes with a widely available oil, and regular coolant replacement.
 
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