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5w20 vs 5w30

Old 04-23-2019, 12:42 PM
  #51  
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Originally Posted by 0-TO-100_Real_Quick View Post
Mine is coming up on 130k miles. I bought the car with around 70k miles, still original engine. Only ever used 5w-20.

I try to keep oil change frequency to around every 7,000 miles.

I'm debating whether to even pursue the Sohn modification at this point.
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.

Originally Posted by New Yorker View Post
So then 47.5K+ miles with not a single engine problem to date is about right for the Renesis.

Got it.
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.
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Old 04-23-2019, 01:03 PM
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Originally Posted by UnknownJinX View Post
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.
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?
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Old 04-23-2019, 01:23 PM
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Old 04-23-2019, 01:30 PM
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Originally Posted by 0-TO-100_Real_Quick View Post
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?
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)
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Old 04-23-2019, 02:22 PM
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Originally Posted by Fijibluefg2 View Post
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!
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Old 04-23-2019, 05:04 PM
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Originally Posted by New Yorker View Post
So then 47.5K+ miles with not a single engine problem to date is about right for the Renesis.

Got it.
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?
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Old 04-23-2019, 08:03 PM
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Old 04-23-2019, 08:22 PM
  #58  
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5w30 is recommended in the Mazda RX-8 owners manuals in ANZ and other warmer countries.
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Old 06-09-2019, 08:47 PM
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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.
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Old 06-09-2019, 11:07 PM
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Originally Posted by Tonycar107 View Post
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.
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Old 06-10-2019, 09:11 AM
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Originally Posted by UnknownJinX View Post
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.
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Old 06-10-2019, 01:24 PM
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Originally Posted by Tonycar107 View Post
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.
What oil would that be? Pretty much no oil sucks so badly it can't protect an engine for at least one cycle.

Originally Posted by UnknownJinX View Post
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.
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!
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Old 06-10-2019, 01:44 PM
  #63  
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Originally Posted by Steve Dallas View Post
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.
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Old 06-10-2019, 04:53 PM
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Originally Posted by UnknownJinX View Post
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?!

.

Last edited by Steve Dallas; 06-10-2019 at 08:54 PM.
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Old 06-10-2019, 05:10 PM
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Originally Posted by Steve Dallas View Post
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!
Rotella t4, it's was in my wife's vw tiguan 😂.

I own an rx-8. I'm a little ocd with maintenance.
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Old 06-18-2019, 10:38 AM
  #66  
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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.
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Old 06-18-2019, 05:19 PM
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Originally Posted by Tamas View Post
Warming up the car for 5-10 minutes accomplishes only one thing: wasting fuel.
With all due respect...nonsense.

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...
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Old 06-18-2019, 05:27 PM
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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.

Last edited by UnknownJinX; 06-18-2019 at 05:30 PM.
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Old 06-18-2019, 05:29 PM
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Originally Posted by jcbrx8 View Post
With all due respect...nonsense.

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...
What "pressures"? If you mean general oil pressure, you are incorrect. Thinner oils produce lower pressures under the same pumping force.
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Old 06-18-2019, 06:30 PM
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Originally Posted by Steve Dallas View Post
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.
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Old 06-18-2019, 09:19 PM
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Originally Posted by jcbrx8 View Post
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.
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.
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