TsM

Hey guys, once this bad weather is over I plan on taking my 07 RX-8 to the Mazda dealership and having some maintenance done. I did have a few questions though, and I hope someone here can answer them. Sorry if this has been asked before.

1. As far as an oil change goes, I want to stick with what Mazda recommends(5W-20) but I WOULD like to stick with the best of the best as far as conventional oil goes. If I didn't want to mix oils, and wanted my own oil put in, would I have to have the oil drained, on top of a crank case flush in order to get ALL the oil out that the previous owner was using? Is this the best way to drain the car of any previous oil and start fresh?

2. What brand of conventional oil do you guys recommend as the best? I read Royal Purple, Castrol, and Mobile 1 are pretty popular around here but I'm not sure if they are strictly synthetic or not.

3. I also need to have a transmission flush and was wondering if you can buy your own brand of transmission fluid and ask the mechanic to use it. If so, what transmission fluid is the best?

Thanks guys.

ken-x8

You'll probably get hammered for asking the most commonly asked questions. But before that happens and a moderator has to step in to break it up:

1. Don't flush old oil out. All the brands and acceptable types (API Service, ILSAC) are compatible. Whatever they flush with, if not oil the specified, will be harmful. Just start using what ever you want to use.

2. The favorite brand of conventional oil here is Castrol GTX. Just stick to a name brand that meets the API spec. RP and Mobil 1 are synthetic, Castrol makes every kind you might imagine.

3. Since you're talking "flush" I presume you have an AT. Don't know about those, but in general stick with a name brand that matches what Mazda specifies. Most shops will let you provide your own fluids, but ask at the place you're going to.

If you post the name of the dealership you're going to, either here or in your regional forum, odds are good that folks will be able to tell you if it's a good one or not. Dealerships always vary, and among Mazda dealers knowledge of rotaries really varies.

Ken

TsM

Thanks for the reply. I knew oil was talked about frequently but I figured I'd ask while I asked my main questions about the transmission. I actually have a manual but the term the mechanic used was that I need a transmission flush. Do manuals not need one? This is my first manual so this is new to me.

Also, if it's not too much to ask, why is a crank case flush harmful? Why would you ever need to do it then? Also, last question, if I don't flush and start using Castrol, how many oil changes later would I be running Castrol 100%? Thanks

BTW, I'll search for these answers but I figured I'd ask you while you were still online.

ken-x8

Whatever they flush with is not going to be engine oil. So whatever does not come out after the flush is a contaminant. It's worse on the 8 than on other cars because there's a lot of oil in the oil coolers, so you'll never get it all out. Before detergent oils, there were people who would drain oil, fill with kerosene, run for a few minutes, then drain and re-fill with oil. So the fresh oil was thinned with a little kerosene. Ugh.

There's a similar deal with brake fluid. Never wash internal brake parts with anything except brake fluid.

I think that when they do a power flush of an AT they use AT fluid. They pump it through, rather just drain what comes out by gravity. AT does have a lot of odd passages that probably benefit from that.

It will take an infinite number of changes to be 100% castrol. Just figure the amount of oil in the system, the percent you replace, and raise to the power of the number of changes.

Flushing a manual transmission is bunk. Maybe it makes money for the shop. But it's up there with engine flushes and 99% of fuel/oil additives.

Ken