TOFUDRIFTER

Hey guys, I've been running 5w30 in my fb for a while now and I've been hearing from the local rotary guys that I need heavier oil otherwise the bearings are gonna go bad, plus the heat of the rotaries, it would just be a good idea. I agree with them on that, but I have a few concerns. Will the oil be too thick to get through the OMP? The guys that reccomended the change in weight to me all have the omp gone and premix with 2stroke... So I don't know what I should do.. suggestions? If I should take the omp out is there some sort of online guide on how to pull it off? I know where it is, but Idk if its just a pull out and you're good deal. Thanks guys!

deadphoenix52

iTrader: (2)

i run 10w40 in both the 8 and the 7

Siraniko

iTrader: (13)

20/50 for many years

K-Tune

iTrader: (26)

20w50 is perfectly fine during the warmer seasons.

Jeff20B

iTrader: (13)

20w50 is overkill. Only use it if you have poor low rpm oil pressure, like an R5 shaft with non checkball oil squirters stock.

peejay

I used to run 5W20 all the time. That engine also had the beehive, so oil temps were probably no lower than 200F all the time. And I'd run it until the temp gauge would peg and the radiator would start fountaining.

When that engine finally urped the apex seals due to severe housing wear and heavily V-ed out rotor slots, the bearings and E-shaft were the only good things left in it. Engine died a young death, only had 211k on it...


I run 20W50 in my high RPM engines, but a stock 12A is not a high RPM engine.

j9fd3s

iTrader: (3)

Mazda/Idemitsu did an oil study for the R26B engine, and they choose a 50 weight for that, on the flip side of the coin, every Rx8 runs 5w-20.

so cliff notes, for a race car you run at least 40 weight. on the street 20 or 30 weight is totally fine

T&B rotary

I run rotella 15w40 does just fine in my 12a!

Sgt.Stinkfist

iTrader: (6)

i use 15w50 mobil1 all the time now, used to run rotella 15w40

DivinDriver

iTrader: (15)

Spec for my SA calls for 20w50 based on temps in my area. -20 to +150f

Qingdao

iTrader: (3)

I'd hate to live in a place with ambiant temps outside of that!!!! :O

Oh... and I use Rotella 20-50 cause thats what the book says.

BrGreenSA

iTrader: (1)

10w40 has been doing the job for me, now if only my fmoc would stop leaking, then i wouldnt have to top it up every couple of days....

peejay

That's the thing. Mazda specifies 40 straight-weight (foams less than multi-viscosity) in all of their competition literature.

On the one hand, a competition 2-rotor engine can be expected to make 85-95ft-lb per rotor, or 140-150hp per rotor, and can be expected to live the majority of its life between 7000 and 9000rpm. Keeping the rotors and eccentric shaft stable is crucial.

On the other hand, a stock 12A makes 50ft-lb and 50hp per rotor and spends most of its life below 3500rpm, with peak power at 6000. Even with uncorking things at both ends, it'd not going to make significantly more torque, or be useful over about 7000-7500. And it's still going to spend the majority of its time well below 3500.

And both engines use the same size bearings.

You CAN run 20W50 in a stock 12A with no changes to anything, but IMO all you're doing is wasting fuel and throwing away what little horsepower you have available to you. Which is why I was running 5W20 all those years.

xXGslseSleeperXx

very nice!^ 20W50 for track(little added protection at that high temp but engine can handle pushin that wieght) and 10W30 for daily driven fb!

xXGslseSleeperXx

i would like to try 20wieght and see if feel a lil less resistance in pick up tho

AXA

iTrader: (2)

I read the the entire thing and I am comfuse about what oil to use...
I am between 20-50 or 10-40 for what I have read here...

xXGslseSleeperXx

^track car in hi rpm range=20w50
daily driver=10w30

DreamInRotary

iTrader: (49)

10w40 here. When i was a young(er) dumb(er) rotorite - not to say I'm experienced and/or smart now - I ran 5w30 in the 12a.

I have an OP gauge below my filter, right above the beehive and with 5w30 pressure cold was about 75psi and 10w40 runs about 85 to 90psi on startup. So it is thicker, runs with more pressure, and doesn't flow as freely - but its what ill be running for a long time to come.

j9fd3s

iTrader: (3)

that's the thing, on the street, anything from 5w20 to 20w-50 is fine, it doesn't matter what oil you use

mazdaverx713b

iTrader: (91)

for 14 years, i've been using Castrol 20W50 in the summer and in the spring and late fall i use 10W40. i go by what Mazda reccomends. i ran 10W30 in my RX-8 though, completely ignoring the 5W20 weight suggestion. it boils down to personal preference. i just feel more comfortable running the 20W50.

TOFUDRIFTER

I do beat the hell out of my 12a, I run it hard and high almost every time I drive it.. ill probly up the weight a bit. Thanks.for the help and suggestions!

nycgps

iTrader: (4)

except that almost all rx8 engines have abnormal bearing wear, only in the us. rest of the world mazda recommended at least 5w30. engines in the us gets bearing wear down to sometimes pass copper even as little as 50k miles. those who use heavier weight have zero issues

nycgps

iTrader: (4)

it does matter actually, if u hate rotary, you can always use 0 or 5w20

OneRotor

iTrader: (3)

I have been running 5w50 recently. low viscocity at low temperatures (start-up), high viscosity at high temperatures. Best of both worlds (since I run it hard every time i drive it...)

j9fd3s

iTrader: (3)

its true that lighter weight will wear more, but i have seen zero evidence of abnormal bearing wear in the Rx8. the factory study is based on new parts in controlled conditions, while looking at the internet is not. the people i know with Rx8's have had zero trouble with them. its actually kind of interesting that everyone on the Rx8 forum seems to be on engine #6, but the people off the forum have zero trouble. one of my friends doesn't even change the oil!

i think you could make the case that looking at the Rx8 forum is what causes problems with the car.