So straight 30 or 40 weight?

I've never used anything like that in any car.

My Nissan uses 5w30 and i used 20w50 in my rx7 unless it temps were freezing.

But i may of had that 20w50 in my rx7 in the winter sometimes, Idk if thats a bad thing (this was when i lived in Rhode island)

I think the main problem with synthetics (i think) is when it burns it leaves more carbon deposits behind.

There is only one problem with using modern synthetic engine oil in a street car: $

Don't knock being Evil. :devil:

I think it was their intent to give general guidance for the working VI rather than the exact grade. Technically, "30W" and "40W"is not the same as "30" and "40", but given my experience with race slang I assume that they intended to mean oil in that general range, such as SAE 30, 40, 10W-30, 10W-40, etc. Those who are severely stressed out over this issue can contact them for clarification, but personally I am not concerned with the minor details.

Also, Mazdaspeed Motorsports Development is a support team for thousands of Mazda racers, and not a race team in itself. Various race teams will obviously use whatever they feel works for them. Many racers prefer multigrade oil because the viscosity adjusts better to the temperature, which lets it remain thinner in colder temperatures and thicker in hotter temperatures. Downing Atlanta, known for their endurance racing, is on record as using 20W-50. As stated in the quote above, some race teams use thinner oil, sacrificing protection for a little more power and/or fuel economy.

Anyway, the reason I posted that link was to show that 30 and 40 "weight" oil has worked just fine in race car rotary engines for decades. I did not mean to imply that you should stray from the recommended oil chart found in the factory service manual or owner's manual for your car.

Monograde oil is pretty much outdated for street cars. The only monogrades that I have seen lately are intended for trucks, race cars, or engine break-in. However, some synthetic oils are able to meet both multigrade and monograde specifications.

Well, maybe, but what I'm thinking is, we spent enough on useless shit on a daily basics. Can of Soda, Snacks, condoms (ok, this MIGHT be an important thing :lol:), etc. so I mean if one can't afford that 10-20 bux extra for every oil change that's done like every month or so. then he/she shouldn't be driving. That's just how I see it.

If the excuse is "I just wanna save money", then people might as well get a Geo Metro or Corolla. Rotary and Saving money does not belong in the same sentence.

MuHahaAHHAAHHAHAHAHA :lol:

You should check out RX8club, people take Mazda's "5w20 recommendation" as freaking bible, even when there are so many proofs of engine blowing up and worn out bearings in just 50K miles, they just gonna say Mazda knows best we know nothing ... worst is, only NA gets this "special" recommendation, the rest of the world they recommend 0 or 5w30, hey ppl still use 5w20 like it's holy water for the engine. grrr :lol:


I will use Monograde oil if NYC stays hot all year long :)

I'm not sure how different our engines are but synthetic does not burn completely,I have yet to read an offical article that proves the residue left from synthidic has killed one of our engines,but I personaly want a clean burn and as little carbon and or residue as possible. I own an 8 though not a 7 also Mazda recomends 5w-20w to pass emission standards. Which is BS. But for a lot of 8 owners who are making payments use of a good 10w-30/40 voids their warranty .

I thought Synthetic Oil wasn't good for rotary's?

I use Castrol GTX 20x-50.

Modern synthetic oil does burn well, and it burns better than mineral oil because synthetic has less impurities. Synthetic oil that is designed for 2-stroke or rotary engines will usually burn the cleanest.


Yes, most synthetic oil from the 1970s and earlier wasn't good for rotaries, and some of the oil in the 1980s wasn't good for rotaries either. However, most synthetic oil now works fine with rotary engines, and Mazdaspeed Motorsports Development even recommends synthetic oil for rotary race cars. The main problem with synthetic oil is its high price, which makes it a poor economic choice for most people who just drive their cars on the street rather than professionally on the track.

See the Rotary Engine FAQS on the Royal Purple website:
Royal Purple FAQ | Synthetic Motor Oil Questions Answered

Idemitsu makes oils specifically for rotary engines:
http://www.idemitsu-usa.com/

I added 2 quarts of mobile 1 synthetic 10w30. I'm in california, bayarea/sacramento. Am I going to be fine? Just bought my first FC

You just voided the car's 3-year / 36,000 mile warranty.

Oh snap!! Its ok I have 191k on it. Rebuild soon

Doesn't synthetic oil last longer before it breaks down compared to conventional oil?

Recently i did an.oil.change with Mobil1extended life synthetic 5w-30 for my 200sx ser (sr20de non turbo), it claims to last 15,000 miles.

I normally use castrol gtx (same weight) and change it around 8,000 miles or so.

I notice when the oil has alot of miles its seems thinned out and blows by the piston rings at high rpms, and sometimes while heat soaking idling.

That's really interesting!

So the synthetic oil used for rotaries are 20w-50 as well?

I am seeing two extremes mineral vs synthetic. what do you guys think about semisynthetics. A lightly driven car may benifit from semisynthetis.

Yes, but the rotary engine shears the oil pretty badly, supposedly due to the eccentric shaft. As far as I know, Royal Purple is the only company that recommends extended drain intervals for rotary engines. I would recommend sending the oil out for analysis to see how well it holds up to your particular driving situation before extending the drain interval.

Sometimes, yes.

Personally, I don't see any point in that. However, some race teams do mix their own blends, and many of the commercial "synthetic" pre-mix/2-stroke oils are a blend.