7k-mile change is IMO pretty long for conventional and still stretching a bit for synthetic, especially considering each oil change only catches half of the oil.

But heh, if you have UOA to back up your decision, that would be fine.

I recently did a 2k-mile change, but that's more because I had to do the brake and clutch lines, and that required me to jack the car up, so why the heck not. 5W-20 also is for cheap when on sale.

Uh, yeah? My RX-8 was also pretty problem-free at that mileage.

As long as you keep on the top of the maintenance, that doesn't sound too strange.

If you want to talk about the bad reputation the RX-8 has, I think a lot of built up before coil issues were apparent, and those alone probably killed a bunch of good engines.

I use Royal Purple's synthetic with their oil filter and filter mags. Never had a UOA, though that might be worth doing and sharing. I'm due for another change now, and just had an autoX event the other weekend. I just glanced at Blackstone's website. Anyone have experience on what kind of test to have performed? Or maybe there's a better company?

:lol:

there are more expensive companies. Blackstone’s reports are easy to read and understand.

Get a standard oil oil kit and when filling out the sheet, ask for TBN and TAN in the comments. Both are $10 extras but will tell you active additive (TBN) and acid level (TAN)

Noted!

It's not remarkable. There are many examples that make that mileage. Some don't. Call again when you're at 80k, in another 14 years?

:yelrotflm

5w30 is recommended in the Mazda RX-8 owners manuals in ANZ and other warmer countries.

https://540ratblog.wordpress.com/201...-test-ranking/

Everyone should read this. It's ridiculously long but I went out to the garage and drained the brand new oil out of my wife's vw right after reading it.

I used to recommend this as well, but there are some people who start to question the testing method, mainly with the fact that the test doesn't accurately represent the real world conditions.

Take it with a grain of salt.

I've been reading through some posts of the people questioning his methods recently and I do agree with some of their points. It's not a real world comparison to an oils ability to protect. Unfortunately it's the only somewhat real test that I've been able to find on an oils capability.

What oil would that be? Pretty much no oil sucks so badly it can't protect an engine for at least one cycle.

Spec Miata guys have totally drunk the Kool-Aide. They run Quaker State UD 0W20 just to the bottom of the dipsstick and change it after every race. More HP and OUTSTANDING wear protection!

That's the thing, I really don't see the point of overthinking this on a family car that's not driven hard. I can imagine most family cars aren't driven past 4k RPM, if that. Even the cheapest oil from Walmart would be okay in that case, provided it's changed at the recommended intervals.

As for the Miata guys... Is there any UOA to see? Would be an interesting set of real life data to confirm if this testing is accurate.

No idea. I don't follow it that closely. But, if you go to a Spec Miata race, you will see the green oil jugs all over the place. The fact that it has been in regular rotation for more than 1 year without "teams" moving on tells me the stuff is at least good enough. Miatas normally use 5W30, BTW. I use 0W40 in mine; maybe I should switch?!

.

Rotella t4, it's was in my wife's vw tiguan 😂.

I own an rx-8. I'm a little ocd with maintenance.

I typically use conventional 5W30 oil in my 8's. I have been using Toyota brand motor oil and it has treated me well in my 8's. I had switched over to 10W30 on my last engine shortly before it lost compression in the rear rotor. Though I feel it was no fault of the oil's. In my RX-7's I always use Castrol GTX 20W50 and have had excellent results with that oil and weight. The 7 did call for 20W50 however.

With all due respect...nonsense. :nono:

Oil viscosity is a function of temperature and determined at 100C. Therefore, allowing the car to warm, i.e. say from 70 to ~180F, allows the oil to reach stated viscosity and be most effective. Not doing so increases pressures and decreases effectiveness. Alternately, one can drive "easy" keep rpms low for 7-8 mins....until oil temp, & viscosity, reach normal operating temps. Then zoom... zoom... :ylsuper:

That's what people are saying, don't idle to warm up, but also take it easy until the car is fully warm.

Idle to warm up is a waste of fuel on any fuel injected vehicles, piston or rotary.

And the number in front of W indicates cold flow viscosity. Granted, it will still be thicker than hot, but a 5 oil at room temperature is still thinner than 20 oil at room temperature.

What "pressures"? If you mean general oil pressure, you are incorrect. Thinner oils produce lower pressures under the same pumping force.

PRECISELY! The oil is thicker when cold... causing increased pressure under same pumping force. The oil thins as it warms to operating temp... causing less pressure under same pumping force. :yesnod:

OK. I made a snap judgement and took you for one of the typical [being nice] still fighting the oil wars. You obviously know something about physics and chemistry, and it has been 20 years since my last course back in pre-med, so I'll bow out of the discussion. Most people believe that, thanks to VIs, a 0W40 is basically as thin as water when cold, and as thick as sludge when hot. I figured you were caught in that trap. The confusion comes from lack of understanding between viscosity and viscosity groups.

Regardless, running over-pressure when cold is not much of a problem, as it is engineered into the design of the engine. Letting it warm up for 30 seconds and driving casually until hot is perfectly fine, unless boosted or other considerations warrant more caution.

Isn't there a high mileage thread where someone hit 200k miles on nothing but 5w20? No Sohn, no premix, ... dealer serviced. Been reading a bunch of oil/premix thread of late just as a refresher for myself. Maybe after 13 years of ownership with almost 90k km, I might want to try something different. After reading those threads I came away concluding..... that there are no conclusions on what concoctions or methods extend the service life of the Renesis. Therefore I am sticking to my current method of reduced OCI with 5w30 Castrol GTX.

1 car hitting some mileage on some regiment is not remarkable. We have many threads about cars that didn't. It's a game of odds, every decision should be made so it increases your odds, but in the end there are no guarantees. That's why premixing, to me, is a no-brainer. The worst case is it does nothing, the best case is you get some extra miles out of your engine. The cost is minimal.

Loki - same reco. Premixing seems logical and has been done effectively in RX-8s with no impact to other systems. The Series 2 had a boost in oil injection points AND more oil output so it seems logical that: (1) premixing increases lubrication in the engine and (2) having good oil quality improves all-around engine lubrication. I'm running 5W30 with very frequent OCIs (1000-3000 miles) using WalMart SuperTech 5W30 - API SN-rated.

Well said. If the series 1 engine had enough lube by design, they wouldn’t have upgraded the series 2.

It makes sense logically to increase lubrication inside the chambers to help extend seal life as much as possible until the inevitable does happen.

Im using 10w40 in Florida. Ran started fine and produced good used oil analysis even during winter with the same oil and starting it at 30F in the morning.

Plenty of rotary engine builders suggest using the thicker oil after they’ve seen may too many premature bearing wear.