Hey guys - on my '04 series I i changed the oil regularly, drove the car a little harder than normal (I owned an '85 GLS-SE for 18 yrs before the '04), and the car was still running pretty strong at 120k miles when a kid took my front node off. So I bought an '09 R3 - beautiful and running strong.

So I read about synthetic oil here and there and get totally confused as to whether to use it or not and how long it should last.
So help me clear this up - I can go longer between changes w synthetic - right? At 3000 miles the oil is still pretty clean. Maybe i wont push it to 10k or 15k like on my bimmer - but surely longer than 3,000 miles...?

My other question - I had the engine coils failed on my 04 at 30k, replaced them myself, the other set lasted 100k. On my '09, it appears that based on previous owner records, they had not replaced them so they failed at 95k. I replaced them myself. That's is my worst fear when i go on a long trip and I carry a spare one from my last purchase. SO - when the coils fail again - is there a way to know which one failed? There are no burn marks or visible "wear" - just curious...?

Your help is appreciated

 

Synthetic is bad for rotaries so it's strongly suggested not to use synthetic. And I believe that royal purple should also not be used. I use gtx 5w20 motir oil in white bottles. Those are not synthetic. You can pick your own brand though. To find out which coil failed you would have to take out the coul and see if there are white marks on it. Some of them might even have white stars or something that looks like a star. Some people say that you can't really judge by white marks and you should test it with a special thing. The white marks have worked for me pretty good. If a coil fails, you will get a misfire. 0301 is front rotor 0302 is second rotor. Blinking cel is also a misfire. Pretty much when you get a misfire you should check your couls first and then go from there.

 

Synthetic is bad for rotaries....that's a big statement. Proof?

 

Quik, all wrong.

Oil: https://www.rx8club.com/new-member-f...thread-248952/

Coils: http://www.rx8help.com/doc/tsbs/Igni...-%20UPDATE.pdf

Posted From RX8Club.com Android App

 

Damn. And can you believe that I read a lot of stuff on these subjects on this forum. Like synthetic doesn't burn as clean as regular oil and that it ruins seals. I guess it's up to the person which oil they want to ise. And the coils. I read about white marks and when I got a misfire, checked the coils and changed the ones with white marks. . I guess I gotta keep on reading

 

I had read most of that - but reading it again...still confusing!
But I appreciate your help!

 

Hi Quino,

A very safe schedule for maintaining an RX-8 is to stick to the factory recommendations on oil: mineral oil every 3,000 miles [edited] or less for a daily driver with only OEM filters (which are pretty inexpensive online).

BTW, RX-8 oil stays pretty clean looking unless it has been way too long between oil changes. That is because it is mainly used to lubricate the eccentric shaft and associated bits, and is injected into the rotors for lubrication and burning. It does not see the same conditions that it would in a piston engine.

I pay the dealer to change mine with Castrol GTX 5W20 with Mazda filters every 3,000 miles to make sure there will be no problems should an engine replacement under warranty be needed. But, I drain and fill the oil myself after every track day, so it ends up being changed much more frequently than every 3,000 miles--basically once a month on average.

As for coils, that is a tougher nut to crack. One of my rev B coils failed at less than 20K miles. At that point, I read all the pertinent information and decided to just spend the money on a BHR kit so I would (hopefully) never have to worry about it again.

The problem with coils is there is no way to visually inspect them and reliably pick the bad one. You have to test them. And, after you have found the bad one and replaced it, you might be right back there a week or two later looking for the next bad one. In light of this, I decided I would replace them all at once as regular maintenance, which is an expensive approach. This is the logic that led me to the BHR kit. Even without using that approach, if you plan to keep the car for more than 60K miles, the BHR kit starts to make economic sense.

 

stvnscott,

Unfortunately, it has been proven through used oil analysis that the viscosity breakdown of 'non-synthetic' oil by 2,500 miles is past where it should be and excess bearing wear starts accelerating rapidly. This is due to the significantly higher stress and sheer the 4-stroke oil is subjected to on our e-shaft than piston engines.

For us, the factory recommended change interval is not a good idea on dino. If you go to a high quality synthetic, then yes, the longer interval is more acceptable. However, longer intervals, even 5,000, can introduce a degree of sludge and deposits into the OMP lines that can clog them eventually. Installing a SOHN adapter to never have dirty oil being pulled through the lines and switching to a high quality synthetic for the high sheer environment we have is the ideal solution.

 

Great. Always more to learn. I should be OK since I change my oil so frequently, but other people should not listen to my bad advice it seems. I have to admit that I have not read the entire used oil analysis thread. Perhaps I will modify my behavior to use synthetic as my drain and fill and top-off oil, so I will at least be using semi-synthetic most of the time.

I have thought about going to a SOHN adapter, but have not researched it enough to make the decision. What kind of warranty impact might that have? I have been treading carefully in that area, hoping to get at least one "free" engine from Mazda before my warranty is out.

 

If you run the SOHN, you would have to remove it (and associated reservoirs, etc...) before bringing the car to the dealer if you wanted warranty service. While it won't ever cause any actual problems, there is legal justification for denying warranty if you bring the car to them with it installed.

 

With a 2011, I'm not sure you can have a Sohn. The OMP setup was one of the big changes for series 2 Renesi.

 

Yup, I have avatars and signatures turned off

The SOHN isn't compatible with Series2s.

 

Research concluded.

 

5w-20 is asking for a trouble in the tracked car, especially if it is mineral...

5w-30 any synthetic will be fine for the street at 5K intervals

5w-40 syn for the track

 

I'd prob stick with 3k mile change interval. Maybe its because I do a lot of stop and go driving, but my oil is usually black by 2500 miles, which is when I change it. 5k I wouldn't push.

 

I actually just read about this in street rotary. In short there is no issue with using synthetic if the engine isn't run too long with mineral oil. Basically use whatever oil you break the engine in with. If you switch from mineral to synthetic or vise versa the gaskets and bearings can inflate or shrink and cause leakage and wear.

Like mentioned previously I recommend 2500 mile oil changes.

 

That mineral vs synthetic BS has been parrotted since the 1970's, but if you read it in a book it must be true, no ....

 

Mineral oil IS synthetic.

The "synthetic" label just means that the additive package helps it retain viscosity longer, and the word "synthetic" is incorrectly used.

The base oil is still synthetically formulated for every single consumer motor oil, regardless of what label is on it.

 

The last thing I want to do is reignite the oil wars, but I do have another question or two.

What about the synthetic additive package does Mazda find objectionable in the Renesis? And, have people had problems with engine warranties if they are found to have used synth oil?

The reason I ask is that I am considering a change to my oil strategy, which would include using full synth 0W40 when I do my own drain and fill. That would give me the limited benefits of ending up running semi-synth with a viscosity boost. That would also keep my service records with Mazda in good order.

 

Actually it isn't anything objectionable. They simply never tested it and therefore are 'playing it safe' by recommending against it.

Gasoline leaves more carbon in the engine than any oil anyway.

Yes, people have had warranty trouble when they told the dealer they used syn. But only at dealers who are similarly just trying to cover themselves. Lots of warranty replacements have happened on syn by just not telling them. They can't tell without careful testing anyway, and wouldn't be able to back up a denial in court


Chosing non-syn is fine, just change a whole lot more regularly. 2,500 max

 

Without reigniting anything, I can share what I've figured out so far from reading papers on machine lubrication, lubricant chemistry and stuff like that. Maybe it will be helpful if you're rethinking your oil strategy. Giant asterisk: I have some chem eng background, but never touched oil, so grains of salt for everyone.


The oil you put in your engine, regardless how it's labelled is generally Group III oil, which usually means a mineral oil stock hydrocracked to break complex hydrocarbons into a more homogeneous mix of lighter ones, creating an oil that is more resistant to oxidation. This is where oil starts getting labelled synthetic.

A better oil, Group IV is PAO, is still derived from dinosaurs but by a longer process that results in a very consistent collection of small molecules. Some, but far from all synth oil (especially high end racing oils) are 100% PAO base, (apparently Mobil 1 is as well), while many are either just hydrocracked dinosaurs or a blend of some dinosaur and some PAO.

So, the thing you don't want in your engine is varnishes, because they make things stick to each other, close up tight tolerances and inhibit heat transfer, but varnishes are basically just oxidized oil molecules settling out of solution and sticking to hot parts, same way burned butter sticks to your cooking pan.

PAO and hydrocracked oils have different oxidizing behaviors: PAO will resist oxidation for a long time and at higher heat, but when it reaches a certain % of oxidized molecules in solution, the resistance falls off a cliff. Hydrocracked oils, on the other hand, oxidise steadily from the day you put it in the engine, and higher temperatures accelerate the oxidation process more. But here's the kicker: fresh Group III hydrocracked oil can dissolve its own deposits, whereas fresh PAO cannot dissolve PAO deposits, or anything else for that matter.

PAO sucks at dissolving things, including additives you want in oil (detergents, water control additives, anti-foam, dry lubricants like zinc), so you have to add other stuff like diesters to keep additives in solutions.

This is going somewhere

So how do you use your car?
If you're driving around town like a regular consumer, your oil decays at some predictable rate. Change it often and it doesn't super matter what the oil is.

If you're tracking, you need the extra protection of a high performance oil, so PAO or better (there's better stuff but it's $$$), otherwise you're wearing your bearings and contact surfaces. So you need a 'synthetic' regardless.

But what happens when that synth dribbles out of the oil injectors onto the apex seal? We hear stories of deposits left by synth oils (good luck figuring out which blends). I think it just sits there, on the seal, the seal spring, the housing, etc. If it's PAO, it will eventually decay, and no new oil nor fuel is going to clean it up. Fuel can dissolve varnishes left by Group III oils, but not so much with PAO.

Likewise in the crankcase and bearings: we said earlier that PAO's resistance to oxidation and deposits decreases fast above some % of oxidized molecules in solution. Remember how you can't drain all old oil from an RX-8? There's a solid few quarts in the oil coolers, which is old and contaminated. Now guess what happens when that mixes with fresh oil? Insoluble deposits.

So I don't know, but this is the closest I have to an understanding of all the different symptoms and recommendations seen here and made by Mazda.

Short answer: not all synth is good for you, not all synth is bad.

My solution was to go Sohn, so that no engine oil sees the inside of my rotors, and run LiquiMoly Synthoil in the crankcase. I don't know what blend it is, somehow oil companies don't like to disclose the mixes. But I like the molybdenum disulphide for extreme pressure protection, since the new oil standards (SJ I think) cut down Zinc additives (because Zinc kills cats.. yet another reason to not burn engine oil in the stock oil injection system).


A few references, but not all. Give a good rundown imo:
Is Synthetic Oil Better?
http://www.worldpac.com/pdfs/motul_S...1.2-Colour.pdf

 

Thanks Loki, i learned something. I might have to revisit opinions.

Is there anything that -does- remove PAO deposits? You said mobile1 0w40 is pao, which i was using without sohn for 30,000+ miles, and seafoam / water (under a combustion evironment) was stripping carbon. Most of that i assume is from gasoline, but a % from oil makes sense.

 

So apparently PAO is often combined with esters / diesters which do dissolve varnishes (as well as additive packages). I guess it's down to the particular blend of oil how well it will dissolve varnishes. But the thing is, you need a flow of solvent to dissolve any kind of solid deposits, so the apex seal problem is probably more of a mechanical one than chemical even. In your case (and mine), it might actually be OK because a lot of 2 stroke oils are esters. Motul seems to be one.

I don't think I know enough about 2-stroke oil yet, to be honest. :/

When to Switch to a Synthetic Oil

This machinery lubrication website is really good for this type of info, but there still aren't straight answers for rotaries. We need Mazda for that :/

 

Im confused... So I've been using 5w20 mineral oil. Should I switch to 5w20 synthetic?

 

Very interesting stuff. Thank you for taking the time to post all of that. I am off to take a nap now, but when I wake up, I will spend some time on more research.

Just to clarify, when I say I track my car, I mostly mean I take it to HPDE events, where I run it hard for 20-25 minutes at a time, and do that 6 times per track day for about 2 hours of total track time spread out over about 8 hours. Another type of track day is time trials, where I actually drive it hard for about 30 minutes all day. The point is, I am not killing the car for 2 or more solid hours like some guys do.

On track days, I run ~0.5oz per gallon of Lucas semi-synth 2 cycle JASO FD oil as premix.

As I said before, I take the car to the dealer every 3,000 miles for their $25 Castrol GTX plus OEM filter special (5W20, although they will use 5W30 if I ask them). After each track day, which is 1 or 2 times per month during the season, I drain and fill the oil without changing the filter, which yields 3.5 to 4 quarts. I assume that is about half the oil in the system, so I have the ability to affect the type and viscosity by about 50% when I do my own service. Since my oil ends up being changed at least once per month, I think I am OK almost no matter what I do, but I obviously don't mind improving on the situation. If using synthetic and/or increasing the viscosity makes sense, I will certainly do it as long as it does not cost me significant warranty hassles should problems arise down the road.