legokcen

Advance Auto Parts has had 5 W 20 every time I've been there. May not always be Castrol GTX, but they have something.

Gomez

Mazda Australia import and sell the oil you see in Wakeech's post above.....but we can put just about anything in an Australian 8. Depends on the climate to a small degree. See pic attached from my owners manual.

Gomez.

Gomez

BTW, "except Europe" does not necessarily mean U.S.A is included......refer to your own owners manual. In this case, it means Australia/New Zealand and possibly some Asian markets.....

Gomez.

rx8cited

Gomez,
Thanks for posting the "Recommended Oil" page out of your Aussie RX-8 manual. Very interesting to see choices other than 5W-20!
rx8cited

SpacerX

I'm running Motorcraft 5w20. It, like a few other offerings, is marketed as "synthetic-blended" due to the performance properties of the type of oils in it, but is actually a blend of highly-refined mineral based oils (group II, II+, and III). Apparently, there are actually very few "pure" (i.e., PAO-based, groups IV, V, etc.) synthetics still out there -- Amsoil is one.

This particular motorcraft 5w20 oil has shown some excellent used oil analysis results. You can check out the UOAs and related discussion at The Oil Drop Forums

Not much data submitted for RX8s yet...

picosrx8

I understand that many people have thier own brand of oil and filter. But I am really suprised that Mazda is recommending a thinner vicosity oil for the USA than the rest of the world. Last time I checked we do have some pretty friggin' hot climates here! Being S. Florida native, my Dad had always told me that warm climate cars needed a thicker oil. I have used nothing but Valvoline 20w50 in all my cars and trucks for more than ten years. This is my first rotary engine so I was curious what everyone else is using. So the question remains...Will a more viscious oil do any harm or is a good idea for a warm climate?

dauntless

when i first posted this question, i thought that it would lead to some pretty pertinent questions...thanks to you all and those who will add in the futre thread. i really am wondering about this oil weight and really am trying to find out what is best for this renesis engine. i know that it is the first run and am cautious to know how it is performing with the 5w20 vs. 5w 30.

is there really any difference in performance, mileage, and any noticeable wear on the movable parts depending on the oil, or is it still to early to tell, i.e. not enuf feedback?

douglas

rotarygod

The rotary is not easier on oil than other engines. It is actually quite the contrary. Unlike conventional engines, the rotary expells almost 1/3 of it's heat through the oil system. Only oil runs through the rotors and this is how they get cooled. From a cooling standpoint, the oil is nearly as important as the antifreeze.

It may seem like the rotary doesn't have any "crankcase" gases but this too is false. It does. Highly modified turbo rotaries need a catch can since oil may actually get blown out of the engine through the vent on the top of the intermediate housing. Normally this just gets sent back into the intake tract but many people cahnge this to a catch can. Ever heard of anyone on the forum complaining about oil in their intake? That's why. They just don't know it and dealerships haven't figured it out yet.

Gomez

picos, and others.....I believe Mazda specify different oils for different markets for a number of reasons. The oil in the 8 is injected and burns as part of the combustion process. The injection is controlled by the PCM, and the PCM in Nth America has a different flash to suit local conditions. You're using "L" or "M", we are using "F" or "G". You use a lower grade of fuel than we do, we use 95/98 octane only. Our service schedule is different to yours, we get a service every 6000 miles.

Ultimately, the above reasons and you're different driving environment (long periods of city idling etc), varied climate, and buyer demographic (the car costs 60 grand here) could IMO account for the different oil spec.

Gomez

takahashi

I support Gomez in this.

There is a chart in the user manual that clearly state the rangel of oil should be used in different outside temperature range. I think it is a very useful guide for your area.

Rotary787

Which is a better synthetic weight 5W-30 or 0W-20 for the south (25 to 100 degrees). I don't want to start the synthetic debate. I have heard all the pro's and con's & so can anyone else with a search on synthetic oil.

Anyway, I will probally Mobil due to availability-but it is only made in 0W-20 & 5W-30. I would think the 0W-20 would be better for synethtic since it does not break down (as opposed to a higher weight for a normal oil). But again it is hot here and the summer is long so maybe I should use 5W20.

rx8cited

takahashi,
The thing is that the US chart has one temperature range and one oil grade choice - 5W-20!

The Aussie page that Gomez posted had many temperature ranges and many oil grade choices.

Gomez,
Keep in mind the octane numbers are spec'd differently in the US compared to overseas. For example, the US manual recommends we use 91 [ (R+M)/2 method] = (96 RON or above).

When you said "we use 95/98 octane only" I assume that was in RONs? If so, that's basically 91 R+M/2 - so no difference in fuel octane-wise then to explain the oil grade differences in the manuals.

rx8cited

Gomez

Today I've learnt something new! That's a good thing, thanks!

Gomez.

picosrx8

So if that is the case, why not use a mutiweight oil for higher temps ie 10w40 or 20w50?
Another thing I noticed today while picking up some oil, Valvoline 5w20 and 5w30 bottles says right on the front "improves gas mileage". I guess there is some truth to that old trick.

w2aew

Maybe rotarygod can back me up on this... Given that the oil is as important in removing heat from the engine as the coolant - you need to make sure that you maintain proper oil FLOW in addition to oil PRESSURE. The thinner oil will FLOW more than the thicker oil at the same pressure. The 10w40 or 20w50 won't flow at the same volume/rate as 5w20 or 5w30, so won't be as effective in removing heat from the engine.

Mikelikes2drive

why dont people read their MANUALS?!? only 5w-20 and u can find it anywhere castrol gtx is what i use

TRZ750

Hey Rotarygod you are only partly correct! The main topic here was type of oil, not what the oil does. YOU ARE CORRCT THAT THE OIL IS VERY IMPORTANT FOR COOLING, BUT ANY OIL WILL DO THAT. Probably even transformer oil. In fact Mazda did a goof back in the 70's when salesmen were saying that the rotary was a maintenance free engine. They actually had a recall of the oil dip stick to shorten it so the low mark was a quart low and the end was the danger mark. (I was suprrised that the RX8 dipstick is as long as it is.) Arrond town the engine didn't need much oil cooling and the user would let the oil get low. Then one trip on the freeway and the rotor would overheat, expand, and damage the side housing. The rotary will use a small amount of oil because of the metering oil pump, but suddenly jump in oil comsumption when the oil seals were bad. People that only checked their oil once a month would get in a bad habit and let it get too low and damage the engine. This was common with the 74 & 75 Mazda's as many of these sat in storage near the port during the energy crises and the salty air would rust the steal side housings.

A none turbu rotary DOES NOT HAVE BLOW BY GASSES INTO THE OIL SYSTEM! Blow by gasses are burning gases from the combustion chamber than get by the gas seals. For the rotary that is the apex, corner, and side seals. Apex seals just leak to the next chamber. The corner and side seals leak to the area between them and the outer oil seal. Mazda put a groove there to carry these gasses back to the side intake ports. The intake ports are always under a vacumm, even a full throttle, so suck the gasses back into that chamber. Anyone that has taken a rotary apart notices the carbon build up on the outer oil seal, but not the inner oil seal (unless the outer o ring is shot). In fact any blow by gasses that did pass over the two oil seals would heat the o rings bad enough to damage them. Now with the RX8 Mazda went a step further because of the side exhaust ports and added another sealing ring to prevent any gasses passing to the oil seals.

Anyone can take the oil filler cap off. Place their hand over it and have someon rev the engine. You will not feel any pressure. More likely you will feel some suction from the recirculation valve (PVC).

Now a turbo is different as the intake is now pressurized and not in a vacumm when at full throttle. SO some gasses can get forced by the oil seals into the crankcase. Also the turbu itself has oil lines to it and a return. A internal turbo problem can force air back to the engine crankcase.

Any oil in the air box could be caused by the new side ring not sealing and allowing exhaust gasses into the crank case, but if that is occuring the oil seals o ring will be failing soon, which is a much bigger problem. I actually think something else is doing that like just some oil spiled into the intake track durring assembly or transport. Especially the ones I read about mentioned red oil that didn't look like egine oil. I accidently overfilled my 8 at my first oil change as it doesn't hold the same full 5 qts. my 7 or REPU did. Since it was only ~1/2" over the full mark and my rotary knowledge, I did nothing. Now I have ~2400 miles since the change and no signs of any oil in the air box.

rotarygod

My response was directly aimed at your very incorrect response that rotaries are easier on oil than other engines. They aren't so don't try to nit pick my response apart. You yourself admit that you may in fact feel a vacuum through the oil filler cap. If there was no pressure (vacuum, boost or otherwise) entering into the "crankcase" as you are trying to point out, you wouldn't feel anything. You are contradicting yourself.

I never stated that any certain oil would or would not serve to help cool so I don't know where you are going with ALL CAPITAL LETTERS!!! Oil isn't a cooling medium in any water cooled engine except the rotary.

I don't need a lecture by anyone as to how the rotary works. I KNOW!!! (Just thought I'd throw the caps back at ya! :D )

Gomez

Posting a pic to bring up lost earlier pics.....



Hopefully this'll work, swoopster.

Gomez

Yep....it did.