You can't use synthetic oil in rotary engine! Oh, that's right I use synthetic in Rx8.

 

Hey everyone,
I was wondering what kind of motor oil I should use brand/synthetic or non synthetic/viscosity wise in my RX-8 2004 with 50k miles on it in ARIZONA that I can buy at Autozone or some retailer immediately.

I have read like half of the threads that have been created in the past ranging from '03-'11 now about debates on the oil type, brand, makes, name, etc.

I just want a simple answer to my problem stated above and specs of my car.
I don't want any explanations or make it a debate.
I don't want to make this anymore complicated than it should be.

Thanks in advance my RX-8 friends!

 

10w-40 or 20w-40 for hot arizona

http://www.autozone.com/autozone/acc...er=852677_0_0_

20w you might have to source online

Lot of the west coast guys love their 20w especially in the summer where temps might hit 100F on the daily, 10w would suffice as well

 

20w-50 will work great as well. I use royal purple in mine and have for years with great success. I am not a fan of Mobil 1 in the rotary from a personal experience.

You can use good old Dinosaur oil as well.

The bearings look much better on the motors I have torn down w/ synthetic and a heavier weight.

I know I have made posts in this thread before just under a user name that is not associated w/ my business on the same topic.

 

RIP IT how many of those rx8 engines failed/had to be rebuilt due to the bad bearings?

From your experience what is number one cause for rx8 engine failures?

 

Thanks for the advice and recommendations!
I have been using 10w-30 for the longest time and was wondering if that would be still acceptable in ARIZONA.
I know that the 10 means for colder temps and 30 for the Hot conditions.
ARIZONA does hit really cold during winter times so would be 20w-40 not a good idea then for winter time?
It get's around -48F during the winter here and needing to start up the car at 7AM would it cause any problems when using the 20w-40?

 

am i reading that right ... arizona gets negative 48F winters ?! lol

Assuming you meant +48F then you technically would be ok with a 20w, but its probably better to drop down to a 10w just for the added protection on a colder startup. I would assume between now and winter you probably have an oil change under normal driving?

 

You really want to second guess Mazda's engineers? Really?? Remember, they had to get an engineering degree, study engine design for years, and then somehow get through some mighty tough job interviews to get their their jobs with Mazda – jobs that I'm sure will always be highly desired. Jobs where Mazda can pick any engineers they want; the cream of the crop. So I would use 5W-20 or 5W-30.

But hey, I never owned an RX-7. What do I know?

 

I love this arguement.

Mainly because I entirely agree that Mazda's engineers probably know entirely what they are talking about.

However, anyone that believes that R+D engineers are the ones that get listened to on details when it comes to producing a product for the consumer market has never worked for a corporation or been an engineer.

I'd also bet there there is another section of engineers in Mazda working on how to improve fuel economy, that insist on 5w20, against the opinion of other Mazda engineers that developed the rotary that insist on 10w40 or higher.

And then add in the warranty analysts that don't know anything about engineering who insist on one thing or another, as well as the marketing reps that decide that they want to ignore anything either one says...

And well, what you are getting is probably not what those engineers wanted in the first place.

I come from a family of engineers, work with plenty, most of my friends are them, and I work for a Fortune 50 corporation. I know first hand how much of the "right" decision gets thrown out the window in favor of the "easy" decision.


I'm not saying that 5w20 is wrong, or that it is right.

I'm just saying that your reasoning isn't as solid as you think it is.

 

shhhh ... you are going to wake the debate monster's

 

^ Those are fair points to bring up. And well said, too.

 

The problem is that people say 5W-20 is recommended so we should use it but that is not true across the planet on an engine that is the same across the planet. Oil has always been recommended based on the environment the engine is driven in. This has not changed (well in other markets anyway).

 

Yup.

The weight of oil that I use changes on a regular basis, depending on the season, forecast, what I expect to be driving like (since I leave this geography frequently) etc...

I've gone from as low as 0w20 to as high as 20w50.




Another example I have, with the rotary, is that I would lay money that the R+D designers pushed for a separate 2-stroke oil source for injection, but they get blocked and that gets rejected by other people within Mazda in favor of a more consumer friendly method of pulling from the oil pan.

In this case, the best, most ideal, engineering solution WAS NOT selected, and we know this.

Oil weight is entirely viable to have been dealt with the same way.

 

Being an accountant in the engineering services industry it has been my experience (and practice) to RARELY if ever support or approve the best options put forth by the engineers. It always gets down to how cheap can we go while still looking like we are doing our job. You know, to maintain the profit margin and attempt to make whatever it is idiot proof.

 

Most of the engines I have torn apart have fallen in the 60-80K range. Some higher some lower, but that will give you an idea.

The bearing wear on these motors is far worse than previous 13B engines. Many of the MSP's I have seen look as though the bearings have closer to 200K in wear and are not reuseable.

I am in Oklahoma and I tried running the suggested oil weights when my car was new even though my experiences w/ prior 13B's told me otherwise. The trial of the factory oil weights lasted one week in the summer. It gets quite warm in Oklahoma in the summers, for example today is 104* plus some humidity, so lets just say it's hot. I could hear the bearings clicking as the oil film on them was not thick enough to support them at idle let alone under load. If you have not hear this sound it is unique as the rotary is very quiet, and this is a very distinctive sound. At that point in time I switched over to my normal oil weights of 20w50 and 10w-40 in the winter. I would personally never go below 10w-30 on this motor and in the heat no lower than 10w-40.

As for other wear. Some motors show more apex seal wear than others. Which is due to apex seal lubrication. A lot of this I believe to be how well owners pay attention to their oil levels.

However I personally do not like the shorter apex seals that are found in the MSP and believe they are one of the reasons for failure. Similar to some of the problems found in the S5 13B's. Basically as the seal wears it is getting smaller, loosing the height of the seal in the apex seal groove. On one side it has 2 springs pushing against it and on the other a wall it is riding on. If the seal is wearing prematurely from lack of oil it will start to chatter (vibrate). As you can imagine this is very hard on the seal and sealing surface. That chatter and vibration will wear the seal faster. Now as the seal is wearing and losing its height it will be able to vibrate more as it gets closer to the edge of the seal seal slot until it finally lets go causing a catastrophic event. I would have like to have seen Mazda use a 2 piece seal that was the same size as the rx7 seal. I know they were trying to accomplish less weight on the seals but I fear that this is on the biggest weaknesses in the MSP.

Also the exhaust port in the side plates causes more heat than the earlier Pheriphial port exhaust housings. This can wear the oil control seals faster, even w/ the extra scraper seal, and also weaken the side seal springs.

I am sure I left out some info, but that is the basics on my findings. Hope it helps.

 

Weird, most of the builders that have posted here have noted little/no bearing wear. Thanks for contributing.

 

Rip-It
Thank you for contributing.
I'm sure you have heard the ads that say that 90% of wear happens at start-up... when your cold oil is working its way through the pump.. or getting bypassed at the pressure regulator. I understand your oil preference based on the higher film strength of the higher viscosity oils.
Can you comment on all contributing factors in the engines with bearing wear. What oil, driving conditions, whatever else...

 

he is spot on.
many of the renesis engines will also have the sparkplug cracks due to excessive heat . That starts a chain of events... all of them not good.
i dont think anyone yet has found the actual root cause of apex seal breakage?

by the way why do yall change oil viscosity with the season? Doesnt your engine get to the same temps winter and summer?
Or is it just the cold start?

 

Rotor bearings typically are on par with the other 13B's. The difference is in the front and rear main bearings.

Most have been relatively stock (intake/exhaust) daily drivers using Mazda recommended oil weights. They are mostly the motors dealers have denied warranty on.

 

Well thanks for some more insight.
I got some royal purple 10W-30 for a quick refill since my last oil+filter change was 1000miles ago.
Since it doesn't matter what oil you throw in it's safe to say it's good for a quick refill right?

 

Crack the plug holes same as the FD. I actually run 20W-50 year round, but some feel more comfortable changing. I have seen 15* differences in water temps between the seasons.

 

Thanks for the info. I am on my third motor is 126,000 miles (first 22k mostly 5W-20, second 74k Castrol 10W-30). None of them saw boost but my current rebuild is at 30,000 miles and I am currently doing a turbo build. I will compression test it when my new BHR coils get in and I will see where I am at and decide then to proceed with the install or reuild it first.

This motor has seen the Maxmart oil pressure regulator, SOHN, no cat, BHR ignition, been premixed, and 5W-40 and 0W-40 since break in. I hope my compression numbers are good and all that money was worth it and my OCD like maintenance habits pay off

 

yes I will but that won't be happening until another couple months because I had an oil change + filter 4 months ago and only put down 1,500 miles on it.

 

I run 0W-40/5W-40 and change it every 3,000. Check out my used oil analysis thread, you can get a good idea of how the different oils stand up. I'm not a fan of Royal Purple, it doesn't meet any standards. I just sent a sample in from this last OIC and I saw some severe temps, I should get the results soon.

 

9k, speaking of used oil, I have been a bit lazy and haven't sent my sample of my RP5w-30 in ... its been sitting on the shelf for like a month, .... still ok to send in?