I know Mazda recommends 5W-30 for everywhere in the world but here, and I'm inclined to believe they're recommending 5W-20 for North America to help meet emissions rules—perhaps at the expense of what's best for the engine. So I'm considering switching to 5W-30—at least in the summer months.

But here's my question…

Is it possible Mazda "factored in" that N.A. cars will be using 5W-20 (not 5W-30) when they programmed the ECU? In other words, even though an argument could be made that the engine was "meant" to run on 5W-30, would switching to 5W-30 be a bad idea because the ECU assumes we're using 5W-20?

 

Use whatever weight oil you want. It doesn't matter. The ecu can't possibly know. There are some that claim that 5W30 makes the engine run smoother than 5W20 but out at Sevenstock, David Haskell was talking about he sees no reason to run anything other than 5W20 in a street car. Their race car runs 5W30.

 

The latest recall has something to do with the OMP rate. They changed it so it pumps a bit more oil. I guess it has to do with the oil weight. Since no one else has this recall(or change in programming)

but as always, use whatever you want. Im a New Yorker and I've been using 5w30 for a while.

 

great i'm filling mine up with some 75w90...

 

Why do you say that? You could run 20W50 and it would work just fine. Now 75W90 on the other hand...

 

now in the summer it runs on 20w50.
Just image the stink of the exhaust of 75w90!

 

These things will even run on synthetic, so oil must not be critical.

 

lol that's funny. Too bad that "synthetics" are just a more purified form of oil!

 

I have read that lighter weight oils have a better ability to transfer heat to the oil coolers which would be and advantage in the RX.

 

Yes the same as too much coolant-mix will make your car run hotter.

 

Oil?

I fill my car up with Butter!

 

I have always run 10w-30 in the rx-7. Will try 5w-30 next time.

 

I just bought some 0W10 from Royal purple..its called Racing 9...somthin like that. Gonna put some in in a few days. should be fun ..............

 

Ja, my neighbor uses Crisco oil in his BMW and Miata

Speed Source said they use 20-50 Valvoline in their race car.

I would not recomend Crisco.

 

When brought the car for an oil change to my mechanics [(pretty savvy guys, used to race, work on high end European cars have friends that raced in alms)] but they ain’t rotary specialists, they suggested I switch to 5w-30. They said that they confirmed this with a local Mazda dealer and he said that the oil is fine. When I was at my local Mazda, the parts manager said that the heavier oil has the potential to not getting to some engine parts (that’s what I understood), saying that nothing but 5w 20 should be used. I am still on AGIP 5w 30, but considering going back to mazda 5w 20.

 

20W50 motor oil is *thicker* than 75W90 gear oil! yeah it sounds counterintuitive but go figger. of course if I was forced to choose I'd still go w/ 20W50 over the 75W90, for other reasons.

 

Are you saying you are running 75W90 gear oil as your motor oil?

 

IS that the reason why Only 5w20 users got this engine recall and failure ? LOL

 

I used 20W50 on my RX-7 in the summer, 10W30 or 5W30 in the winter time, the thicker oil was given me oil pressure that looks more like what it should be.

 

I use dino 5W-30 b/c I think it lubricates better all around in all temps as opposed to thinner 5W-20. I'd be ok with synth as long as it wasn't Mobil 1.

 

The wider the temperature range, the less effective

 

Do you have research to back that up?

So if 5W-20 was more effective, why did it basically help toast 8 engines in temps over 100F?

 

Don't make the assumption that the engines only had issues because they were using 5W20. I guarantee that was a coincedence. That is after all what it comes with and what is recommended to be used. Most people stick to that recommendation. Is it really so surprising that it was some of these that failed?

 

someone got confuse here... i think this thread about engine oil:20W50,10W30,5W30 or 5W20 and 75W90 is for manual tranmission oil and rear differential oil

 

i'm using 5w30 from catrol (anti sludge?) and it's running better than it was before, it had 5w20 syn. or something.

Although, I do plan on getting some Royal Purple at my change (approx. 1k more miles to go)