Gordon, based on the numbers, would it be possible to engineer an oil that DOES become MORE VISCOUS when heated?

Do such oils exist?

 

It's possible to have a fluid with that characteristic, but it wouldn't be an oil as we know it. I'm not sure why one would want one anyway - from an efficiency point of view, viscosity is bad. What we really want is oil film shear resistance, which right now requires a certain amount of viscosity. As oils improve, they can achieve adequate shear strength with lighter and lighter oils - for example, the exotic oils used in Formula1 engines are thin as water, yet stand up to revs of over 19,000 rpm. I suppose an oil that didn't change viscosity at all with temperature would be ideal!

Regards,
Gordon

 

What if this read

First, the oil temperatures remain lower which would seem like a good idea, however too low is not good. The oil is thicker at lower temps, and like synthetic oil causes reduced compression.

Maybe it was a slip of the tongue, or Maolin just mis-remembered what the engineer said. I could see how lower temp oil, would be thicker or more viscus, and thus cause less compression, and thus less air, and thus more fuel that isn't burned. :D

 

That's impossible........it would go aganist the laws of thermodynamics and also the kinetic theory of matter.....

 

regarding fuel dilution, this other thread seems to be interesting

https://www.rx8club.com/showthread.p...+fuel+dilution

Which makes me wonder if maolin's discussion with the engineer was focused more on friction or sealing of the engine.... or maybe if the latter is dependent somehow on proper friction or oil viscosity? The latter seems more significant here, as it seems like a lot of issues deal with the RENESIS' effective compression (dynamic, and we are talking about daily driving so 1k-4krpm). .. like what problems will we see in an engine that happened to draw the short stick on seal clearances, that is also running 5W-20 in winter on oxygenated or ethanol mixed gas, which also might have fuel dilution issues, and so might be running with even less viscosity than it should.


Darn... it seems like theres some chapter in the yamaguchi book about seals that I need to read... can anyone be kind enough to scan it?

 

Multi-viscocity modifiers REDUCE the tendency of oil to thin as temperature increases. They're not used in high enough percentage to REVERSE that tendency.

It only takes 2 points of real-world experience to verify this. 1 - pouring oil into the engine on a cold day. 2 - changing the oil when the engine is hot.

 

no- octane rating is a measure of the resitance to pre-detonation of the fuel. in other words the higher the octane the harder it is to ignite. so lower octane fuels mor eof it gets burned instead of wasted- hence better mileage. why not recommend lower octane than? because pre-detonation(knock ,ping etc) is BAD for your engine.

 

i learned alot from otherpeople including RG and Gordo, Wakeech and others on this forum. plus alot from people i cant name and alot of reading/studying on my own after being set in the right direction by those mentioned.

 

It is not insignificant to note at this point that one of the issues addressed by MSP04 is lack of compression due to low oil injection.
The Renesis is heavily dependant on the oil film for compression.

 

I think the most of the posts here are not meant to "shoot the messenger". But I do think there is some consternation about the number of off-the-mark statements attributed to the "engineer". It's not comforting to think that someone with the title of "engineer", holding these views, is involved in some capacity with the design and production of the RX-8.

It may well be that most of the debate is due to miscommunication. The engineer might have been trying to translate technical explanations into laymans terms, etc. I would love for Maolin34 to take some of this back to the engineer as stated initially, and perhaps that would elicit some more specific and technically oriented clarifications. On the other hand, I'd be surprised if any Mazda engineer would allow themselves to become engaged publicly in technical discussions about the vehicle, outside the auspices of Mazda itself. That just invites too many liability and public relations headaches.

 

Might as well answer this too - I've been a car nut for over 30 years, I have every Road & Track since June 1972, along with a ton of other car mags (I get about 6 or 7 different ones every month). I graduated university with a degree in Mechanical Engineering (BscME 1981), which included a full term course titled "The Internal Combustion Engine in Theory and Practice" :D (one of my favourite courses, of course ). I'm not that familiar with the specifics of the rotary like RotaryGod, but I do OK with general principles... I hope!

Regards,
Gordon

 

Now if only people would actually live by that standard, with everything...

Teach me, what that seems to imply or mean...is the point where the oil will break away and leave the thing it is protecting, well..."unprotected". Oil is used to reduce friction so if it "sheared" it would allow friction, am I right?

I would love it if a Mazda engineer would actually come to this website and discuss stuff with us. Maybe he/she could do it on the down low...not say who he was or who he worked for.

The aftermarket and mod industry is very strong and only going to be stronger so it would be great if Mazda would embrace us to allow us to give them feedback on what we like and dislike about the RX8.

Mazda, if your reading this...LOL

More power & torque
Better fuel economy

Yes, I know those two normally don't play nice (my word for the day, LOL)...but dang it if you don't dream nothing NEW or great will ever happen.

It's been fun reading what everyone has been saying!

 

This entire thread brings back a lot of bad thirty year old memories of spending an afternoon in sophmore engineering lab dropping ball bearings in heated oils and measuring/plotting how fast it took them to hit the bottom.

 

a) Fuel dilution is a problem in every type of engine - not just a rotary but it seems to be more pronounced in rotaries. Fuel dilution causes the oil to thin out and the lubrication properties decline with more and more fuel dilution because gasoline is completely soluable in motor oil unfortunately. In most engines it does not cause any real problems because the oil gets changed well before the viscocity reaches an unsafe level for lubrication - however in a rotary where the oil is needed to build compression this may be more of a problem.

b) Multi-grade oils by definition have properties that make it thicker when it gets hotter. Does this mean hot 5W-20 oil is thicker when hot then when cold? No of course not. Does it however mean that warm 5W-20 oil is thicker then straight 5W oil when warm? Yes because in reality your 5W oil just thickened into a 20W oil when it got heated.

To say that a multi-weight oil does not thicken when heated totally ignores the fact that it is a multi-weight oil. It may be thinner when heated, but it is thicker then it would have been.

 

Congrats! You have reduced way to many heated (words not oil) ideas into something understandable in just two short sentences. Hooray! But we probably all knew this was what was meant anyway from the git go, I know I did.

 

I think the viscosity charts explained it very clearly. Your last sentence is correct and opposes the preceeding sentence. No matter how you slice it, all oil gets thinner when heated. None of them get thicker. This is a problem. HOw do you fix it... you add a polymer to the oil which reduces how thin it gets when heated. THis is where you are thinking "it get thicker." A reduction in the rate of change in viscosity or level of viscousity does NOT imply that the oil is becoming thicker when heated. You are thinking that 5W oil is an apple and 20W is an orange...and that is it possible for the 5W to completely change when heated into an orange. This is the obviously false part. Oil is BASICALLY oil. There is no change or conversion going on... just 5W oil heating... viscosity going down like normal until the polymer gets set loose and SLOWS and STABILIZES the rate at which things had been progressing.

 

on fuel dilution. pardon me for saying ti does not happen. i misspoke. i was thinking it terms of the oil injected by the metering oil pump which should not be making its way back to the sump. also oil in the cooling passages should not ever be mixing with fuel. but of course there are ways for the fuel to get by the oil seals on the rotors and mix with fuel there. note that earlier i did say that fuel dilution is symptom of a larger problem that could lead to a rebuilt engine or new engine. i was thinking it terms of seals wearing out, and losing compression etc. however my point of making that statement earlier was in opposition to what i thought i was reading - that fuel mixing with the oil was the cause of people getting really low mileage. as if the fuel was just running off into the oil.

i said earlier in my first post also. Dont shoot the messengr. he is relaying the info he was given as he remembers/understands it.

 

For all we know, that engineer could have been responsible for the gauge cluster, body panels, or even wiring harnesses. Heck, he could be responsible for powertrain NVH or packaging requirements. In any of those cases, it really doesn't matter what he/she knows about the detailed workings of the Renesis or the properties of lubricating oil. Lacking that knowledge is not going to prevent him/her from doing a good job. Unless this engineer was directly involved with the design of internal engine components, the lubricating system, etc, it's not surprising to me at all that he/she might be passing along incorrect information.

I think this is the most likely explanation. The engineer could have mis-stated some information during translation to laymans terms, or Maolin could have misinterpreted some of what he/she said and relayed a distorted version of the conversation.

Maolin: it would really help to clarify things if you could find out who specifically you were speaking with. The "Mazda team" is very vague. The engineering team working on, say the Mazda6, is comprised of completely different people than the RX-8 team. I don't see any reason why the RX-8 engineering team would be at PDC in Dearborn. I think it is much more likely that the Mazda3, Mazda6, or some new vehicle program team would be visiting PDC given that Ford is utilizing these platforms in upcoming products. If that's the case, then most of what he knows about the RX-8 is probably from conversations with his engineering buddies back in Japan.

 

One thing is obvious by the 2488 reads so far for this thread, and that is that Mazda in general, and MNAO in particular is - to all of us - certainly one of the most secretive organizations that ever existed...and certainly when it comes to "the story behind the story" on the RX-8!

Hell, it seems like any little bit of information, however gotten, is like some manna from heaven(?). It's like the cold war.... there is some little info that comes officially about our car... usually total BS marketing... then through some clandestine way we get dribs and drabs of 'the truth' and debate it endlessly.

Oh for a news conference-like panel of RX-8 engineers with questions coming from the general audience of RX-8 owners... but now I'm really dreaming aren't I?

 

ill work on that - seriously. it is a good idea

 

I wont add anymore to the oil viscosity debate other than there is confusion....heated 5w-20 is "thicker" than heated 5 weight. That is the entire point. The majority of the reason for any mention about oil in the first place was with respect to the use of synthetic oil. The use of the words thinner, and thicker generalize far to much when specific details are very important. The site uses these words very loosely.

In regards to who I spoke to, the last thing that anyone in my position should do is offer up personal information about someone without their knowledge. However, I will see if I can get in touch with him again, and see if he is willing to provide an email address or something. The "Mazda Employees" that I spoke to were here for cold weather testing of the MazdaSpeed versions and 05 models of the 3, the 6, and the 8. This caravan of cars also included the camoed Mazda 3/Volvo S40R prototype. This was a good time to test cold weather as we have seen single digits in Michigan lately.

I suppose that if there are any RX-8 owners out there that would actually like to try some of the things in the thread....which was really the point of sharing what I was told...in fact I have an update to what I myself have done.

Monday my car goes in for a reflash, and a new dipstick. I found a gas station that did not have a sticker on the pump for 10% ethanol, and I used Sunoco Ultra 94. So far there does not appear to be a significant change....but I won't know for sure until I fill back up to check my mileage. The car "feels" stronger running this gas, and my idle does not have that occasional burble that it has since I bought it. I purchase the new paper air filter, but I will wait for this tank of gas to run out before I change something else.

 

thanks for all of the information........ keep us updated

 

droool! Some more fuel for discussion, please!

 

Thank you Maolin for your information and patience. Thanks also for not having a raging ego. Were you permitted to get close to the Mazdaspeed cars they're testing?

 

Hey...what about me, I said something to that effect....No love for rx8wannahave....no love

I think Mazda should do something like that...don't they know we love their RX8. Don't they know we want to learn everything we can about it? I know we have some complaints about the car but we also could tell them how much we love it and what we love about it. Give them props...and let them know our concerns.

Take care, no better yet...LOVE your customer and your customer will love you back. I would love to sit there while people teach me more about the RX8...tell me what they are looking into for the future and "write" down what we dislike about the car.

Who really knows better than the owners of the RX8, not even the Mag's do. We should write up a letter...have everyone sign it and send it to Mazda. Just maybe...we can grow to love the RX8 more...and in turn, love Mazda more.

I'm just all about love today man...LOL