Castrol GTX is basically a poorman's redline oil...its got alot of moly, and is basically a heavily refined Group III oil. Its one of the best cheapest oils out there.

So is Motorcraft 5w-20 semi-synthetic...very cheap, very good wear #'s across the board.

 

I asked my rep at Magic Mazda which oil he would use if he was doing his own oil changes.

His answer? CASTROL

What oil would he NOT recommend using? PENZOIL



Rob in Vegas

 

One page ago you said he said the dealer used Havoline.....

 

yep and the tech said for his own use he would use castrol

 

ah...I was thinking the service guy was changing his tune...Or that maybe he really didnt know what the dealership used....I see what Rob was saying now..

 

Just an update about my car...

The dealership called yesterday and told me that the computer module has been pulled out of my car and shipped to Mazda for service. The cooling fan has not been kicking on when it becomes hot and they want to do some adjustments to my computer to make this happen. They said they have seen this mainly in automatics.

But, after all this turmoil, I told them that to avoid litigation, I want them to buy back my 8 and in turn, I would purchase a Mazda 6 (loaded). I know it's not even close to same the car, but I have lost all faith in my 8 after this mess.

I'll let you know what develops....

-Lance

 

Since you're not taking your car back it probably doesn't matter but did they also change your engine? I'd be worried about the damage already done if your fan wasn't working correctly to begin with.

 

If your getting a 6 ATX, please make sure to get the 6spd. The 5spd ATX's have horrible overheating issues.

For more information on 6 issues/modifications
http://www.mazda6tech.com

(Sorry for the midtopic plug, but I wanted to make sure he doesn't jump one car to land in another problem zone)

 

Hmmm...the plot thickens.....

 

i have the marble sound in my engine...usually when cold. i also notice i do not use as much oil as i used to. could the engine be oil starved>?
has anyone noticed these two symptoms together?

 

yes some AT PCMs are getting sent to MNAO for work.

 

Wait wait wait , This is complete BS, Doesnt the Lemon law come in affect if this occurs 4 times and the dealer cannot fix it

 

Lemon laws are state-specific and, therfore, can vary from state to state. There is NO national lemon law.

 

I filled my 8 with 87 octane and had mazda see if they could fix the knock issues that it is having. Well, they ran some cleaner throught the engine to remove any carbon and told me it is fixed. They aslo said that I should only use 87 octane from now on and that is what Mazda is now recommending. I dunno about this fix of theirs.

 

Interesting... I've been paying a lot of attention to the cooling fan lately, and have noticed that when I park it and it's not that hot out, the cooling fan runs a long time. On some extremely hot days, however, I've heard it shut off before I can even get in the house, or not even come on, after parking in the garage.

 

me too! my fan used to stay on forever...now i hardly ever notice it.

 

I don't get it. As I recall, 87 octane is printed in our owner's manual as the minimum quality of fuel to be used.

Your engine was knocking with 87 octane? That's not good.

My understanding is that 91 octane is recommended by Mazda for performance purposes, not to prevent knock.
That's what's confusing me. They said this is what they are now recommending? Or this is what they have always recommended as the minimum?

Does this mean we should not use anything other than 87? Even higher grades?

It seems like either you misunderstood what you were told, or (probably more likely) the person who spoke to you did a very poor job of explaining things.

Personally, I've been using premium grade since day one because I'm a bit afraid to use anything less, given the credibility of Mazda that has been called into question regarding the whole North American oil grade/EPA thing...

Not trying to be alarmist, just trying to get the record set straight...

 

^I'm just telling you what the man behind the counter said to me. Anyway, I'll run 87 in my 8 A/T like he said and when it knocks again I'll bring it back to them. I took the 8 for a spirited drive tonight and so sar it has not knocked. However, the ambient temperature was only 66 fahrenheit so I'm not surprised. I'll have to wait untill temperatures are 80+ before I will know for sure that 87 octane will work in my 8 with out knocking.

 

Higher Octane = more knock resistance
Premium = higher octane and more detergent

What your service writer said doesn't make sense.
--R

PS. more knock resistance should allow the computer a leaner mixture and therefore more performance.

 

^ I know that and I'm sure they do too. I just wanted to know why my 8 knocks on 87 while most other 8s do not. They (the mazda tech)believe that the higher octane fuel leaves deposits (carbon) behind while running at lower RPMs and that is why they "decarboned" it. My wife drives our 8 through town at low RPMs during the week. I'll drive the 8 hard this weekend to see if the engine has carboned up again while using 87. If it knocks I'll take it back to the shop. BTW, I'm talking about the automatic 8

 

My service tech told me the exact same thing: Run 87 only because higher will just produce carbon deposits.

 

The car is made to run on 91. Use the good stuff.

 

It seems to me that Premium gas with its detergents would be better for deposits. After all, that's why detergents are added. Also not all gasoline is the same, different states have different recipes and regulations. 87 in Massahoma isn't necessariy the same as 87 in Oklachusets. In the past cars designed to run on 87 have been known to require higher octane due to gasoline regulation changes.

At any rate, it seems unlikely that advice to use lower octane to reduce detonation can be correct, especially since such advice contradicts the owners manual. Maybe there are some here who know more.
--R.

 

I just returned from octane and carbon build-up school -- i.e., I just read:Summarizing what I've learned from those articles and our owner's manual:

• Our RX-8s should run fine* on 87 octane fuel, such that the octane level itself should not cause knocking. (*Fine = not cause damage, though not necessarily with optimum performance)
  
• A buildup of carbon deposits may occur for a variety of reasons, and if that occurs, that may cause "hot spots" where compression is higher and, thus, the opportunity for spontaneous combustion of fuel (a.k.a. knocking) increases.
  
• If carbon deposits build up, increasing the octane of the fuel should stop the knocking, but doing that only masks the problem of the carbon buildup. The engine would need to be cleaned, which hopefully can be accomplished with an additive -- otherwise, a more extensive repair would be necessary.

 

Very good stuff sharwood. This topic is very interesting. I think one of the problems is related to some design dilemmas that Mazda is probably trying to find the best solution (Compromise) for. I think the Renesis is much more prone to carbon buildup in various parts of the motor than previous rotaries but sufficient oil metering must be provided to maintain apex seal life. Sufficient quantities of oil in combustion I believe can lead to increased carbon buildup. A lot of slow driven versions (Often but not limited to automatics) would potentially suffer the most.
One of my suggestions, although maybe not financially practical would be superior apex seal materials which would reduce oil metering needs.
Here's a stange riddle: A prominent engine builder that I know told me he has to to compensate his air/fuel ratios when forced to run higher octanes than necessary for certain races by richening.