RotorMonkey

I always use 10/40 but will the heavier weight be better? Is there also a safe oil treatment additive that I can use? Fuel Treatment (Clean injectors)?

Thanks,
Jason

LUV94RX7

iTrader: (3)

Castrol GTX 20w-50 is what my engine builder recommended.

Ken

mightyslash

I think it depends on how hard you drive the car and the weather. 20W50 should be ok as long as it's non synthetic. Correct me if I'm wrong.

black99

I didn't know 10w40 was ok for our cars. I usually run Valvoline Racing(adds 15hp lol) 20w50.

Don't know about any fuel treatment though to clean the injectors.

martini

I've always used 20w50 mineral in the warmer months. I thin it out in the colder months.

rotorbrain

mazda has a fuel injector cleaner that they recommend. i saw it somewhere. i cant remember. i use castrol syntec 10w-30

user 84205

I use 15w-50 synthetic.... Nice a smooth, you get too heavy and your car will run like poop, no matter what the weather is

rxrotary2_7

i bet this could have been found by using the search button, but maybe i am wrong.....
10w30 in winter
20w50 in summer

Mahjik

iTrader: (1)

Most people don't suggest 10w-40 for FD's due to the additives that are in it.

However, 20w-50 will be just fine. If you are in a colder climate, the 20w-50 will take longer to warm up, which is why some people switch back to 10w-30 in the cooler months.

RedR1

iTrader: (5)

Im in Florida by the coast, and run Penzoil 20w50 mineral.

I havent had any probs with it. Like Mahjik said, depending on your climate. Im not sure how hot/cold Atlanta is, but its on average 75* here.

user 84205

I guess it all depends on where you live...ROTORMONKEY

twokrx7

iTrader: (1)

OEM knows best, refer to your owner's manual, they designed the motor/turbos to work with a particular viscosity and operating temperature range. Read on and flame on if interested.

Just for info, only a hand full of companies make the additives or customize add packs for the major and minor oil suppliers. And, only a hand full of companies make the base stocks that all the oil suppliers buy from, both dyno and synthetic. Exxon is one of the few that do both, but they buy additives for their in house additive blends from the hand full of additive makers. Many other majors use their own base stocks but have one of a few additive companies design and make their add pack. I suspect Lubrizol designs, tests/certifies, and makes the add pack for most of the majors and minors as they are the largest player on the planet.

Even the mom and pop oil suppliers like Royal Purple and a few others buy their additives and base stocks from the same hand full of companies (same folks that customize the add packs for the majors and minors). The advantage for these small mom and pops are, they often design their own add pack not to simply meet the industry standards but to exceed the performance expectations of racers. There is a difference in purpose built oils, but is small and most will never notice it.

The label means little. Walmart oil is the SAME oil that is sold by whatever major they buy from (used to be exxon, changes based on price ... who else but a major could satisfy Walmart's quantity requirements, no mom and pop could).

Most well known majors and minors have excellent quality, little difference from bottle to bottle. Performance differences exist, mostly between dyno and synthetic. Synthetic typcially has less additives and ash when consumed, desirable for engines that burn oil. Turbine oils suffer from additive drop out, Redline comes to mind.

Buy whatever lets you sleep at night and try not to worry about it.

luneytune

I May be wrong but Mazda has a special type of injector cleaner that requires them to do it, I believe you have to buy it by the doz. treatment packs if you want to do it yourself? Anybody know this?

Joseph Schwartz

I have always heard to stay away from 10W-40. I believe it is due to the additives that oil manufacturers add to it. I have used 20W-50 for years with no problems. Since I live in a Tropical climate, I never deviate from 20W-50. In your case, you may have to go to 10W-30 in the winter.

jmseven

Do not use Castrol Syntec. After personal tests, it should NOT be used on rotory engines. 15w-50 Mobile 1 or 20w-50 Redline. These both have been proven performers. There are many write up on this subject....do a search and find the answer.

spyfish007

I agree with Gordon ... I hate these debates. For what it is worth I use Mobile 15w50 syn and it is great. Change regulary and top off a quart every month (which adds perservatives back into the oil making it more effective!) and you should be fine.

rotorbrain

i havent seen any writeups on syntec. i have had no problem with it so far, but i havent had my engine apart either. can you elaborate on these personal tests.

93TTRX7

Rotary Power recommends non synthetic Valvoline 20w-50...so Valvoline it is. Jeff knows far more than anyone I've ever seen

rotorbrain

im thinking about pissing in my oil pan to see if that works. haha. a couple of people have said it. i think that if you just keep it clean then it is all good. we really need to get mazda or someone to release data on what is good for this engine. people are going bald over this. haha. if i had enough money i would do it. in a heart beat, but im only twenty. . . haha. . . a good excuse, eh.

WhtRocket

I've been using 20W50 in my rebuilt. It's seldom if ever really cold here. The original motor would hold good oil pressure with 10W30. The rebuild would not.

twokRx7, what about Redline? I was thing of switch ing because of a relatively high flashpoint, low ash and zinc content. Just waitingfor it to go on sale at Kragens.

Hey if you **** in the pan, make sure it's a Coors ****. The data I found indicates Rocky Mountain Spring water forms a unique uric acid which proves flow .

Johnsrx7

I was talking to an automotive engineer who designs engines for Porsche and Mercedes and he was saying you NEVER use any other weight of oil than the one the manufacture recommends. The different weights absorb different amounts of air which make it harder to compress and move the oil around. The engines are designed with a specific weight in mind and if you use an different weight, you will kill you engine a lot faster than than using the oil that the car was designed for.

RotaryiPAQ

2 years ago when Pettit rebuilt mine Cameron Worth said to use Valvoline VR-1 20w50. That's what they put in mine when I picked it up and what I've used since. I even use it in the winter, but Atlanta area isn't normally very severely cold. Plus, I put in 4 oz of X1-R or XR-1, whatever it is, when I change the oil.

WhiteRXseven

OK not to sound stupid..

SO what does Mazda recommend??
10w-30?? 10w-40???

Can some one tell me wht the OIL NUMBERS mean???
I know higher the Number means heavier weights.
Example 10w-30....: What does the 10w signify?
and what does the *30* signify??

BTW I use STP concentrated Fuel Injector cleaner
periodically.. And always used 10w-30 or 10w-40.
Even mixed when adding oil.. With no ill effect
I know of.. and I am going on 125K miles
on original Motor and turbos and get solid 12psi.

dznutzuk

iTrader: (1)

I use Castrol 20W50 Semi-Synthetic here in Athens. That synthetic trash talk that it harms rotary's is just that. It was a problem back in the 70's I think and one company's syn. oil was harming rotary's but that problem was fixed and no one has had problems with any other syn. oil.

jmo87

iTrader: (2)

i run castrol 20w50 and i like it