I just took my "8" in for it's 20k service on Thurs. I got the standard oil/filter/tire rotation. Today I checked my oil and to my surprise I found it overfilled by almost a quart and dark as hell. I checked my paperwork and found out it had been serviced with Synth Mobile 1 10w30! I'm a little pissed cuz you would think a Mazda dealership would know synth oil is horrible for our cars, and it's not even the right weight. I was gonna go back to the dealership where I had the service done but they are closed today. I guess I'll be there bright and early Monday morning.

The black is normal since only about 50% of the oil in the system is actually changed when draining the oil pan. The "new" oil gets black almost immediately. Don't fret about that. I've had several analyses done on the oil after 3K mile intervals and it tested fine. Looked bad but no problems found. Just make sure you change it regularly.

The dealer will probably tell you that the entry on your worksheet is the standard printout for all oil changes and that the oil they put in yours was 5W-20, non-synth. Maybe they did, maybe they didn't. You might want to take the pamphlet that came with the car into the dealership with you. The appropriate section is below:

don't fret too much about it being synth oil. I got a DVD from mazda stating that the renesis' seals are compatable with synth oil.

I just took my "8" in for it's 20k service on Thurs. I got the standard oil/filter/tire rotation. Today I checked my oil and to my surprise I found it overfilled by almost a quart and dark as hell. I checked my paperwork and found out it had been serviced with Synth Mobile 1 10w30! I'm a little pissed cuz you would think a Mazda dealership would know synth oil is horrible for our cars, and it's not even the right weight. I was gonna go back to the dealership where I had the service done but they are closed today. I guess I'll be there bright and early Monday morning.

Not to be rude but it sounds like your dealership knows more than you do about oil which I will admit is impressive for a dealership. Why does everyone wrongly think synthetic oils are bad for rotaries? It's not! Get over what it is called and look at what it does and how well it does it. "Synthetic" oils are better refined and more pure. I'd hardly see an issue with a better oil being bad. Go do a search. There are many threads on synthetic oils and many of us here use them. Synthetic oils are wonderful. Also don't worry about 10W30. At operating temperatures it's no different than 5W30 and that's what the rest of the world outside of the US uses. The only reason the US uses 5W20 is because Ford who has a controlling share of Mazda has stated that for efficiency reasons based on our testing methods that they will recommend nothing but 5W20 in all American sold cars. Leave it alone. Your car will be fine. I'd be happy if a dealership used synthetics as opposed to lower grade, less refined conventionals. If you want a worse product, have them change it. Otherwise leave it alone. My only concern is with the higher oil level but remember that we don't have a crank down in the sump. It is just a storage area for oil. It isn't as critical in rotaries as it is in piston engines but the oil fill level should still be adhered to nevertheless.

..synth oil is horrible for our cars,..

Sigh! Will this ever end?

I appreciate everyones input. I won't worry about it too much but, it does say to use 5w20 non-synth oil in the owner's manual. But whatever, if rotarygod says I'm good, I'm satisfied.

I don't know about that 50% oil onyl being changed thing. Doesn't sound right. That is correct for a drain only on an automatic. I bet if you put an oil drain pan under there and drained your engine you'd get just about all of it. As for the over fill, that's a great thing. Engines are designed to be overfilled a little bit. The only problem is that if you overfill it too much your oil pressure can increase too much and you might have other problems.

I would definitely find out why your oil is still dark (unless the fresh oil is dark). Should be a golden brown. After my oil changes I can't even read the dip stick. It's possible they didn't drain the filter and replace it first. Vacuum will hold some oil in the filter and line that feeds it. On my 7's I would crack the filter and let it all drain out into the pan. Then I would remove the filter. I found there to be almost 1/2 a quart that holds up in there.

I don't know about that 50% oil onyl being changed thing. Doesn't sound right. That is correct for a drain only on an automatic. I bet if you put an oil drain pan under there and drained your engine you'd get just about all of it. As for the over fill, that's a great thing. Engines are designed to be overfilled a little bit. The only problem is that if you overfill it too much your oil pressure can increase too much and you might have other problems.

With all due respect, you are completely incorrect and you need to do a little reading in the manuals so as not to provide inaccurate information. The total dry engine oil capacity of the RX-8 is 7.1 US qts. When draining the oil from the oil pan you will get 3+ qts, maybe 4 if you know what you're doing, leaving about 3 qts of dirty oil in the oil cooler and lines. The only way to drain all the oil from an RX-8 is to remove the oil cooler lines and drain them and the oil cooler--not something most people will do considering the difficulty. So, when you add 3+ qts of new oil to 3 qts of old oil, the mixture turns black almost immediately.

EDIT: These capacity numbers apply to the US manual transmission car which comes with 2 oil coolers. The US automatic version comes with one oil cooler so the amount of oil remaining in the system will be somewhat less than that stated above.

"go48" is right about the dark oil thing. not ALL of it comes out when u drain it bc of the oil coolers.


synthetic oil is not recommended for rotary engines, as per mazda's request. i have movies from my work that explain how synthetic hasnt been throughly tested on rotaries and so it is not recommended.
when we replace rotaries at the dealership, the list of instructions include filling the engine with conventional 5-20 because, and i quote "..using a synthetic oil will void the manufacturers warranty..."
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.....when we replace rotaries at the dealership, the list of instructions include filling the engine with conventional 5-20 because, and i quote "..using a synthetic oil will void the manufacturers warranty..."

I would very much like to see a scanned copy of that particular quote. Do you have access to a scanner....or a digital camera??

Thanks,
Gomez.

"go48" is right about the dark oil thing. not ALL of it comes out when u drain it bc of the oil coolers.


synthetic oil is not recommended for rotary engines, as per mazda's request. i have movies from my work that explain how synthetic hasnt been throughly tested on rotaries and so it is not recommended.
when we replace rotaries at the dealership, the list of instructions include filling the engine with conventional 5-20 because, and i quote "..using a synthetic oil will void the manufacturers warranty..."


You talk about synth oil voiding the warranty...what if it was dealership who actually put the synth oil in when they did the oil change?

I suspect that the instructions she refers to are from an internal dealership document. Like you I guess, I can't imagine that is the official Mazda position. Certainly they recommend using non-synthetic engine oil, but I've not see a Mazda corporate statement that using synthetic oil will void the warranty.

"..using a synthetic oil will void the manufacturers warranty..."

Could you cite exactly in what Mazda publication this is stated?
Its not in my Owner's manual, or anything else I've seen from Mazda NA.

Prior to my last oil change (performed by an authorized Mazda Dealer) I researched this quite thoroughly. Finally, when I went in for my scheduled service, I provided them the oil I wanted to use (Royal Purple), and asked them to specifically confirm with Mazda what, if any, warranty issues would be associated with this. They made several calls to Mazda NA, and finally came up with a footnote on some service sheet that said that synthetic oil was not recommended. But they also said it is neither prohibited. The official response was that ANY oil that meets SAE API service specification and weight cited in the owner's manual is sufficient to satisfy the warranty. I had them document this on my service sheet.

So, if you can cite something official published to the contrary, then I would like the reference, so that, 1) I can provide it to my dealer, and 2) send a recommendation to Mazda NA to put out a change page to the owner's manual (since that is the only official guidance that most folks get with their new car).

Jeff

^you won't see an offical position other than not-recommended from mazda...b/c not all synthetic oil is created equal..some is beter than others...so instead of saying "use this one but not this one" they (mazda) found it easier to just put out a blanketed statement of "synthetic oil is not recommended" ....at least that's my take on the whoel thing.

i use royal purple 5w20...racing beat adn various other rotary shops have been using synthetic oils for a loooooooon gtime and found only good things with them. :)

....Like you I guess, I can't imagine that is the official Mazda position. Certainly they recommend using non-synthetic engine oil, but I've not seen a Mazda corporate statement that using synthetic oil will void the warranty.

This is the reason I asked to see a copy...... :wink2: . If it is written in the install instructions for a new Renesis, then it seems Mazda require non synthetic for the first fill. After that, the official Mazda line on synthetic is "not recommended", for the reasons army rx-8 stated above.

I don't believe that sythetic oils cause any harm, but I have been told by 2 dealerships in my area it will void my warranty. I had some spark plug issues a while back and the dealership asked me how long I had been using synthetic oil. I told them I hadn't and they said if I was, it would void my waranty. Anyway, I don't know all the details, but I just don't want to risk something happening and my dealership saying it was because I have used synthetic oils (which I know is not the real problem).

You guys should take a more agressince stance with your dealers. If you do as little as actively follow the TSB's and the reflash issues, then chances are, you know more about your car than they do. You should not be afraid to assert your superiority. I think most of us have had to inform the dealer at least a couple of times of some technical information regarding our 8's. After checking, they'll usually admit they were wrong.

The fact is that we have an official Mazda publication that says you CAN use synthetics. Using it will NOT void your warranty. Any dealer that says that is blowing smoke up your tailpipe.

I appreciate everyones input. I won't worry about it too much but, it does say to use 5w20 non-synth oil in the owner's manual. But whatever, if rotarygod says I'm good, I'm satisfied.

Incorrect, it does not state that in the owners' manual.

You might want to take the pamphlet that came with the car into the dealership with you. The appropriate section is below:

Nubo, this is what is in the pamphlet, sorry not the owner's manual.

Oh my god.

Please guys. Its just that Mazda dont have enough time to test Full Synth Oil (or didnt even test it at all, but ahh Im sure they did)

Its always easier, faster, and cheaper to just say :

"We do NOT recommend the use of Synthetic Oil"

Im using Synthetic, my Rotary is running just fine.

Engine I use Royal Purple(soon I will change back to Quaker State Advance Q, cuz its hard to get Royal Purple in NYC, even tho its good, ahh Advance Q is alright I guess)

Tranmission I use Royal Purple

Rear Diff I use Royal Purple.

nothing wrong, everythign is fine, 8000 miles has pass, many oil changes, still kicking.

Nubo, this is what is in the pamphlet, sorry not the owner's manual.

The maintenance responsibilities of the owner are spelled out in the owners' manual and not elsewhere. The pamphlet is more of a marketing/sales piece and not even all owners received one. And considering the fact that it contradicts the owners' manual in this case (oil requirements), the owners' manual must be taken as the definitive document. It's unfortunate that Mazda itself seems schizophrenic on this topic.