rb67

I bought my 2004 rx-8 used from the dealership and after 3k miles I changed using Castrol GTX 5W-30 when I was in Las Vegas.

Now, I have moved to Michigan and have about 3500 miles since the oil change. Thus it's time to think about changing my oil. I probably won't drive 3k miles between now to the end of winter so I was wondering if I should change with 5W-20 or 0W-20 or 0W-30 etc.

I've still got about 5 qts of fresh 5W-30 if it's not a big deal...

Any thoughts/recommendations?

alnielsen

iTrader: (4)

I use Castrol 5W-20. 5W-30 should be fine.
Mazda specifies 5W-20 for the car in the U.S. and it spins around fine in the winter.

Zacobrav

iv talked to dealers about this and they all say dont use 5w-30 the thing is they dont give an explanation as to why not, so i think that they are full of sh*t. i have an 07 rx8 and use 5w-20 i only have 2000 miles on my car but the 5w-20 works great so far (im located in florida by the way so it does get pretty hot) im assuming that your car has all the recals done so 5w-20 should be sufficient. I'd expect that it is better to use what mazda recommends then something else.

ken-x8

How can you judge if it's working with only 2000 miles?

That makes sense. After all, they did design and build the car.

Ken

nycgps

iTrader: (1)

I use 5w-30 and Im in New York. All year long.

Im planning to use 10w-40 or 15w40 next summer, however.

rb67

Yeah, the reason I switched from 5W-20 was I wanted more protection in the warmer southern climate and the fact that every other country gets either a 5W-30 or 0W-30 type of recommendation from Mazda. From what I have found, only the USA is running on 5W-20....

nycgps

iTrader: (1)

Because thats how they get *better* EPA numbers.

I think the EPA system is retarded(at least in terms of this engine oil related crap)

within a few years we will see more *dead* engines than ever. and Im talking about ALL engines, including piston. then people gonna start wonder why, and blame auto manufactures.

Zacobrav

Quote:
i only have 2000 miles on my car but the 5w-20 works great so far

How can you judge if it's working with only 2000 miles?


That is why i didnt just leave it at it works great.
key words: SO FAR

rb67

From what I've been reading, people only the USA has had really high engine failure rates. Only the USA RX-8's are said to run on 5W-20 (as far as I know) whereas the rest of the world uses xW-30/40.

Can anyone who frequents international forums confirm this trend? That is, other countries experience lower engine rebuild rates than the US.

I realize one other factor is the fact that Americans tend to drive more as a population then citizens of other countries.

alnielsen

iTrader: (4)

The failure in the engine is in the seals and not the bearing surfaces. The failures also happen more in hotter environments (eg. LasVegas) and with automatic transmission cars which only had one oil cooler. Oil, in a rotary engine, is as important for cooling as the coolant. These cars were also driven more conservatively and not driven at higher rev ranges to clear out the carbon.
Your original post, suggested you wanted to know what oil to use in the colder climate. My suggestion still stands. The Mazda recomended 5W-20 for normal street/highway driving.

New Yorker

First of all, I suspect there's NOT a huge difference between using 5W-20 and 5W-30.

To say that Mazda—or Ford—recommends 5W-20 only in N. America just to help boost EPA ratings is certainly a plausible theory—but it's not the only explanation, and it hasn't been confirmed as fact. It's also possible that Mazda feels 5W-20 is just a better match for most driving conditions/the way most people drive here. I'm not saying the "EPA theory" is wrong—but it's not the only possible explanation for the 5W-20/5W-30 discrepancy. And Ford/Mazda are not the only car manufacturers that recommend 5W-20.

If I lived in a really hot environment I'd be tempted to switch to 5W-30, too. Tempted, but I probably wouldn't do it—because maybe Mazda's programming of the ECU (and subsequent 'flash' revisions to the programming) is calibrated assuming the use of 5W-20 rather than 5W-30.

nycgps

iTrader: (1)

ITs not really a theroy, Mazda/Ford is not the only one to use 5w-20. Honda use them as well. Without it, they probably cant even get pass the EPA tests.

When I was in Hong Kong for the summer, I've been to quite alot of auto shops. I chat with couple of the owners there, asked about the Renesis *failure rate in hong kong* and the 5w20 thing. they were supirsed that Mazda wants people to use 5w-20 in the states. in Hong Kong they use at LEAST 5w-30 and most run 15w40. and they all said Renesis are very durable and only few of them failed. Not sure if its correct since Rx-8 is not a very popular car in hong kong.

bxb40

Michigan winter: 5W30 or 0W30
Other times: 5W30 or 10W40
5W30 and 5W20 give THE SAME winter performance! That's what 5W stands for!
You care much if you get the invisible fuel economy, or about your engine health? If you want to protect your engine when it is running, don't go below 30 (5W means it will start in winter, the 20 or 30 means the viscosity at normal engine running temps).
I run 10W40 in summer and 5W30 in winter. Mazda cannot claim that engines built in the same plant can take those grades in Australia, but not in US. There is a correlation oil viscosity(grade) versus ambient temperatures where it is used, and that is universal, for all cars.