Regular or Synthetic
#1
RX-8 "SE3P"
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Regular or Synthetic
I have read a number of different posts about people arguing about which oil is better, but are there any hard facts to prove which one is better???
#4
Registered
The manual specifies 5W20 oil that meets API SL specifications, that's all. It does NOT say anything about mineral or synthetic - so as long as your 5W20 synthetic meets API SL, it's great as far as Mazda is concerned.
As for which is better - there's absolutely no doubt that synthetics are better oils - what it really comes down to is whether the benefits are enough to justify the higher cost, and that always seems to be a personal value judgement. For the technical discussions (the "hard facts"), visit www.bobistheoilguy.com .
Regards,
Gordon
As for which is better - there's absolutely no doubt that synthetics are better oils - what it really comes down to is whether the benefits are enough to justify the higher cost, and that always seems to be a personal value judgement. For the technical discussions (the "hard facts"), visit www.bobistheoilguy.com .
Regards,
Gordon
#5
Momentum Keeps Me Going
Originally posted by RotorMotor04
Well, the manual may just be going by what they endorse, but do they really go by what is best for the car's performance.
Well, the manual may just be going by what they endorse, but do they really go by what is best for the car's performance.
Possibly, a performance car would logically be designed with performance inducing components. The RX-8 indeed is that. Well, 5-20w is certainly a lightweight oil, purpose formulated for both low friction function, and higher engine efficiency reasons. So far, so good. Then, in the rotary's function of dispensing oil to the combustion process, metering a light oil makes sense for optimal dispersion in the combustion chamber.
Possibly, given the rotary's self-destructive history, using an oil that promotes longevity would be a goal to enable Mazda to keep selling them long term. So, seemingly, our low weight oil has that benefit, at least in the rotary, as well.
As standards for consumer oil need to be met or exceeded in order to state this on the can, whatever performance, lubrication, and logevity engineering goals Mazda had apparently are met by the minimum oil specs listed. IMHO anything beyond that may be beneficial, but I doubt there is further documented proof at this point in RX-8 history to that - other than urban legend - race cars not included, as the RX-8 is not normally meant to be one.
Beyond that 'what is the 'best oil' for the rotary is a fun, harmless sport, and everyone can have an opinion for discussion. So I vote for What Mazda endorses is best for the car's performance and longevity.
Last edited by Spin9k; 05-08-2004 at 11:30 AM.
#7
There are rumors that synthetic produces sludge. I am not a chemical engineer. I don't know if this rumor is a fact.
I am also under the impression that synthetics burn at higher temperatures. According to Valvoline's website: "Compared to conventional motor oil, SynPower full synthetic motor oil offers easier cold starting, quicker flow upon engine start-up, quicker heat dissipation and better high-temperature properties."
The Renesis, it seems, was designed very very specifically. My question is whether or not the engineers planned on the oil burning away "quickly" as a 5w20 would and tuned the oil pump accordingly or if they just put X amount in at a time and don't worry about it.
I had a talk with one of the shop guys at Trussville Mazda the other month. They said the '8 didn't need synth (and, further, didn't come with synth as my dealer at a different dealership had told me). They argued that there are certain rumors about synthetic oil, and there are none about mineral oil. They didn't know if they were true either. So, be safe and go with mineral.
I don't think that a synth oil would produce significantly better performance or engine life. So, when the time came, I went with mineral. It's cheaper and proven.
I am also under the impression that synthetics burn at higher temperatures. According to Valvoline's website: "Compared to conventional motor oil, SynPower full synthetic motor oil offers easier cold starting, quicker flow upon engine start-up, quicker heat dissipation and better high-temperature properties."
The Renesis, it seems, was designed very very specifically. My question is whether or not the engineers planned on the oil burning away "quickly" as a 5w20 would and tuned the oil pump accordingly or if they just put X amount in at a time and don't worry about it.
I had a talk with one of the shop guys at Trussville Mazda the other month. They said the '8 didn't need synth (and, further, didn't come with synth as my dealer at a different dealership had told me). They argued that there are certain rumors about synthetic oil, and there are none about mineral oil. They didn't know if they were true either. So, be safe and go with mineral.
I don't think that a synth oil would produce significantly better performance or engine life. So, when the time came, I went with mineral. It's cheaper and proven.
#9
Registered
Originally posted by RotorMotor04
Is it true that synthetic does not burn off as easily as synthetic?
Is it true that synthetic does not burn off as easily as synthetic?
No, it's not true. In some of the actual tests of the physical properties of various oils, synthetics typically shows higher flash points - basically, that's the temperature at which the oil evaporates. Synthetics have higher flash points than mineral oil, given equivalent grades - but that's a good thing, because I'd rather not have my oil evaporating when my engine is hot.
The flash points, however, are much lower than combustion chamber temperatures, and synthetic oils BURN just fine. In fact, synthetics burn much cleaner than mineral oils - I have no idea where the rumour started that synthetics leave sludge, because not only do synthetics not leave sludge when burned, it's mineral oils that leave sludge!! (from the wax in the crude oil that isn't removed in the refining process)
Regards,
Gordon
#10
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Most of the rumors about sludge, not burning cleanly or properly, etc are just that...rumors. And of course there are plenty of rumors about minteral oils as well, especially about <insert favorite brand to bash here>.
I'm not a chemical engineer either, but from what I remember reading the high temperature properties of synthetics do not mean it burns at a higher temperature or a different rate. Plenty of people on this forum do know more about the technical details, so if they're not tired of chiming in every few weeks when this conversation erupts, maybe one of them will do so.
One thing I do know....synthetics (at least Royal Purple, the one I've used in the past) retain their lubricating properties much longer in the presence of fuel dilution. I haven't seen anything to indicate one way or the other as to the performance of the Renesis in this matter, but the 13B-REW was notorious for this.
jds
I'm not a chemical engineer either, but from what I remember reading the high temperature properties of synthetics do not mean it burns at a higher temperature or a different rate. Plenty of people on this forum do know more about the technical details, so if they're not tired of chiming in every few weeks when this conversation erupts, maybe one of them will do so.
One thing I do know....synthetics (at least Royal Purple, the one I've used in the past) retain their lubricating properties much longer in the presence of fuel dilution. I haven't seen anything to indicate one way or the other as to the performance of the Renesis in this matter, but the 13B-REW was notorious for this.
jds
#11
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Originally posted by robertdot
There are rumors that synthetic produces sludge. I am not a chemical engineer. I don't know if this rumor is a fact.
There are rumors that synthetic produces sludge. I am not a chemical engineer. I don't know if this rumor is a fact.
I am also under the impression that synthetics burn at higher temperatures. According to Valvoline's website: "Compared to conventional motor oil, SynPower full synthetic motor oil offers easier cold starting, quicker flow upon engine start-up, quicker heat dissipation and better high-temperature properties."
The Renesis, it seems, was designed very very specifically. My question is whether or not the engineers planned on the oil burning away "quickly" as a 5w20 would and tuned the oil pump accordingly or if they just put X amount in at a time and don't worry about it.
I had a talk with one of the shop guys at Trussville Mazda the other month. They said the '8 didn't need synth (and, further, didn't come with synth as my dealer at a different dealership had told me). They argued that there are certain rumors about synthetic oil, and there are none about mineral oil. They didn't know if they were true either. So, be safe and go with mineral.
I don't think that a synth oil would produce significantly better performance or engine life. So, when the time came, I went with mineral. It's cheaper and proven.
Regards,
Gordon
#13
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I am still amazed at how many threads there are about synthetic oil on this forum. In addition to Gord....'s good information I would like to add:
Mazda have not tested the engine using synthetic oil, and do not recommend using it because of this. However, they are not saying it is worse than mineral oil, nor are they saying you are prohibited from trying it yourself.
One of the most important factors is heat transfer.
The apex seals on a rotary engine reach speeds much higher than the piston rings on a piston engine. I don't have the data on hand, but from memory it was 3 times faster.
The sealing of the apex seals is critical. Moreso than the rings in a piston engine. As temperature rises heat must be taken away from this seal and the rotor housing, partially by engine oil.
Synthetic oil has different heat transfer characteristics to mineral oil. This, combined with the fact that the oil is injected into the combustion chamber and burned with the air/fuel mixture, means that changing the oil type requires a little bit of experimentation by the manufacturer before just flying in and saying "go ahead"!
These may not be the only reasons Mazda do not recommend S oil, but they are important ones.
Mazda are testing synthetic oils on the Renesis as we speak, so it will only be a matter of time...
Cheers.
Mazda have not tested the engine using synthetic oil, and do not recommend using it because of this. However, they are not saying it is worse than mineral oil, nor are they saying you are prohibited from trying it yourself.
One of the most important factors is heat transfer.
The apex seals on a rotary engine reach speeds much higher than the piston rings on a piston engine. I don't have the data on hand, but from memory it was 3 times faster.
The sealing of the apex seals is critical. Moreso than the rings in a piston engine. As temperature rises heat must be taken away from this seal and the rotor housing, partially by engine oil.
Synthetic oil has different heat transfer characteristics to mineral oil. This, combined with the fact that the oil is injected into the combustion chamber and burned with the air/fuel mixture, means that changing the oil type requires a little bit of experimentation by the manufacturer before just flying in and saying "go ahead"!
These may not be the only reasons Mazda do not recommend S oil, but they are important ones.
Mazda are testing synthetic oils on the Renesis as we speak, so it will only be a matter of time...
Cheers.
#15
Administrator
i thought you meant to write that in a sort of sarcastic fit. i was going to follow on with:
but i heard that, for rotaries, synthetics aren't as good as synthetics?! and what about mineral oil vs. dino oil? or is it DYNO oil?
but i heard that, for rotaries, synthetics aren't as good as synthetics?! and what about mineral oil vs. dino oil? or is it DYNO oil?
#17
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Is Mobil 1 5W-20 an okay oil to use. I have heard that pennzoil synthtic is peraphin based, which leaves a sludge in the bottom of the oil sump. is this true???
#18
車の性能の違いが戦力の決定的差ではない ということを
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Some Japanese aftermarket rotary tuners like R magic (SL 0w30), knight sports (SJ 10w50), and RE amemiya(SL,10w40) sell their performance oil, all of them are synthetic oil. These tuners are very famous in the field of totary engine tuner in Japan. Is there anyone having comment on it?
#21
車の性能の違いが戦力の決定的差ではない ということを
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Originally posted by RotorMotor04
Where can you get these types of oils???
Where can you get these types of oils???
In Taiwan some rotary engine tuners carry these oil in their shops
#22
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This has been an age old discussion with rotaries.
One thing is for sure, there have been no rotary engine failured from synthetic oil. Failures happen for other reasons.
One thing is for sure, there have been no rotary engine failured from synthetic oil. Failures happen for other reasons.
#23
on the Mobil 1 web site, under "Why Synthetics" then "Myths About Synthetics"
they say.
"Using Mobil 1 will void my new-car warranty?
With the exception of the Mazda rotary engine (Mazda does not recommend any synthetic motor oils), Mobil 1 with SuperSyn™ will not void new-car warranties. Mobil 1 with SuperSyn™ exceeds the API and ILSAC motor oil service requirements of all new-car manufacturers, both import and domestic. If in doubt, always check your vehicle owner's manual or contact your vehicle's manufacturer. "
Don't if this helps at all, ... i was ready to go buy some till i saw this...
they say.
"Using Mobil 1 will void my new-car warranty?
With the exception of the Mazda rotary engine (Mazda does not recommend any synthetic motor oils), Mobil 1 with SuperSyn™ will not void new-car warranties. Mobil 1 with SuperSyn™ exceeds the API and ILSAC motor oil service requirements of all new-car manufacturers, both import and domestic. If in doubt, always check your vehicle owner's manual or contact your vehicle's manufacturer. "
Don't if this helps at all, ... i was ready to go buy some till i saw this...
Last edited by aboutime; 05-11-2004 at 05:54 PM.