Domza

Theres alot of banter about how the 8 consumes oil, but ive also noted that people are talking about non synthetic oils?

Where do i purchase said oils, and for what expense?

EZZY

do a search, there are a few threads about it already....

auzoom

Yes, a search wiull do you wonders. However a summary is that Mazda says you cannot use synthetic oil in the RX-8 as it has been found, in a few cars, to cause built up in the Exhaust ports and cause performance issues.

Domza

very much so MissyK - for a noob theres alot of "???????" when you're reading those threads.

Revolver

What Kall said Dom.

Some of the gurus reckon there's no harm in using synthetics (and actually prefer them) but until you learn more about the car and get some confidence with what to experiment with, I'd stick to Mazda's rotary oil if I were you.

takahashi

I told you and I will tell everyone. Change the engine oil like me and you will not care what oil you use.

I change every 2 track days or 4000km.

Rotor Convert

Good advice Taka. We change ours every 5,000kms and have used both synthetic and mineral oils. We use a Castrol Mineral Oil now...it's cheaper and is the same weight as the MRO......Oils ain't oils when it comes to rotors.

Just make sure you keep some with you in the boot and never use the engine oil light as a warning for the time to fill!

Good luck and may you learn much on your road to ZOOM ZOOM heaven!

Domza

thanks guys and gals!

takahashi

I will prefer not to mix oil. You can tilt the car up and down to get the oil off the oil cooler hoses and few other dead spaces.

I stick with one oil and change it often - whatever it may be.

labrat

It could be advisable to check it a bit more frequently than that. I look at mine every second petrol fill, or about every two weeks. Consumption is about 200-250mL during this period. I think keeping your oil well topped up keeps the average age of the oil lower, and therefore offers better protection (you can test this yourself with an iterative calculation in a spreadsheet). If you think about it, as the oil level drops, the residual oil in the motor is recirculating faster and increasingly exposed to oxidation stresses, hastening breakdown.

Since the Mazda adivisory about using synthetics, I've changed to the Mazda mineral based rotary oil. I've been thinking about an oil change every 5000km with this oil, since I don't think it is as chemically stable as the synthetic.

Actually, I quite like checking the oil. With so few things to worry about in modern cars, it makes me feel like I'm actually doing something for its welfare!

Ciao

Its a rule of thumb that you change the oil every 5 thou and the oil filter every ten thou.

I use synthetic as I have a turbo on my set up and I dont care what anyone says ,synth oils offer far superior protection .

Mazdaspeed do offer a synthetic oil and their 787 Le Mans winning rotary ran Synthetic Oil

But ,on the other hand if I were to run NA,I would most probably stick with the mazda Mineral ........

Ciao........Baby

Dave

takahashi

Dave the most expansive oil filter is only $40! Mazda one is only $9!

Change the oil filter on every change of oil man! LOL

EZZY

depends on waht you do with your 8. change the OIL filter @ every 2nd oil change is plenty for "normal" use.
you need to factor this into the equation too: it takes extra 1.5litre-ish of oil whenever you change the oil filter.

edit: chanegd the word from "air" to oil"

EZZY

OIL filter...

/cleaning me K&N air filter has been on my mind for the past few days.....

MattRX

Why would you go to all the effort of changing your oil only to leave 1 cup of shitty old oil circulating around from your filter??

The filters are cheap and only take seconds to change and if I puncture the top I can do it without spilling any oil over the side of the engine.

Just my view, but my car has never had the oil in it for more than a couple of thousand K's.

Matt

Revolver

You're entitled to your opinion of course but unless you're driving the car very hard all the time (e.g. regular track and race meetings), I think changing the oil every 2-3K is a needless waste of a scant resource (i.e. mineral oil). If everyone did that, oil consumption would accelerate considerably.

MattRX

I agree, I intended to do oil changes every 5K (with filter) but if you see my posts on the .au forum I had oil contamination issues at the beginning. When you add up every six months Mazda service, a track day change and a couple for **** retentive piece of mind the oil never seems to be in there long.

Matt

Revolver

Oil contamination is quite another matter - that kind of thing mandates a change. However, it is the **** retentive junking of perfectly good oil that I find a little baffling.

Rotor Convert

OIL CONTAMINATION?????

labrat

I mention again that because rotaries burn oil, the regular necessary topping up with new oil effectively prolongs the life of oil between changes. Oil isn't so much contaminated as it breaks down. The lubricating properties of oils have to do with the type of molecules present. In natural or mineral oils, this is associated with the length of the carbon chain in the molecules. In mineral oils, these vary, and are controlled by the distillation process in manufacturing. Thicker oils = longer carbon chains, and thinner oils = shorter chains. As an oil ages, these chains are gradually broken down by a combination of heat, mechanical stress and oxygen. As the average chain length reduces, lubricity decreases. Also, oxidation causes the formation of acids. However, oil manufacturers put additives in the oil to neutralize these acids, but eventually they become exhausted, and the acid content of the oil will rise. These aren't as corrosive as say strong acids as hydrochloric or sulfuric, but at elevated temperatures and over time they can have an effect, especially if water (another combustion product) is present in the oil. Perhaps by "contamination" Revolver might be referring to fuel dilution, where unburnt fuel (short chain hydrocarbons) thins out the oil, and decreases lubricating properties of the oil. This is a danger in motors running rich, where unburnt fuel can dissolve in the oil residue on the combustion chamber walls and reduce lubrication. I suspect that this was the reason for the motor failures in the USA.

Synthetic oils contain molecules which are designed to be more resistant to heat, oxidation and mechanical stress. It is also possible to have greater control of the average chain length of the molecule, and thus on the viscosity properties of the oil. These oils will last longer and are to be preferred if recommended for your motor (which they aren't for Renesis).

I've made a decision to look at changing my rotary oil after 5000km, but I will be looking at its condition before I do so. You can get a qualitative feel for how your oil is lasting by checking the "soot" level, ie., how dark it is. Use a paper towel or Kleenex to wipe your dipstick, and check the colour. If you're really obsessive, keep the scraps of paper from each check, and look at the progressive darkening.

I agree with Revolver that you shouldn't be too fanatical about changing oils. Modern engine oils, even the cheapest supermarket oils are quite remarkable when compared to those of say 40 years ago.

yellowrx8inoz

I imagine they need to be, given the advances in engine technology and complexity over the same period...

Cromax

I would have to revise my first year uni notes (which is something I really can't be bothered doing), but all engine oils have TBN. I can't remember exactly it means, but the higher they are the longer they last. For example, Mobil 1 has a TBN of something like 12, whereas something like Valvoline's "Ghetto" Synthetic (Engine Armour) in the orange bottle with the excruciatingly high ash content has a TBN of 8.

I had a way to calculate the theoretical life of oil before the polymer strength started to weaken to the point where it would tear, but I can't remember how to anymore.

www.bobistheoilguy.com is a very helpful site. He has some practical tests and examples of additives as well, which was quite helpful for me in previous years as well.