olddragger

iTrader: (3)

concur on a lot of points.
would like to add--that side seal problems are not just clearance issues , but also about proper rotor balance WITH the loose clearances. No il is going to solve that. So in time a 10-15 hp lost in the higher rpms is to be expected.

DD oil temps are hotter than most realize on an oem car.
isnt the oil pump and omp volume driven? So the viscosity of the oil doesnt nothing in relation to the amount being pumped. The pressure increases to handle the heavier viscosity.
Heavier wgt oil will run hotter--cant shed heat as fast. But, a good oil can handle 250-275F NP.
Besides get the coolant temps under control and the oil temps will go down.
Diesel oil cleans well and holds its vis.

Give me Horney Goat Weed over any oil any day!
olddragger

nycgps

iTrader: (1)

Good point

but im seeing around the same temp even with 5w20. so 5w20 will "cool better" is not valid. At least for this car & engine.

puch96

The information in this thread is very interesting.....

....also it is interesting a video I found on youtube a while ago (kind of a user guide to the Rx8) in Japanese (probably the video that comes with the car when you buy it in Japan), they recomend a 0w20 oil.....Golden Seal 0w20.....

I will look for the link and post it.....(although probably some of you already seen it....)

Flashwing

My daily driving oil temperatures are within 180 to 200 degrees on any given day in the Phoenix summer when it's 110 to 115 degrees outside. I don't consider my oil system hot till about 220. We also don't have the humidity to aid the cooling process either.

No, the pressure increases because viscosity increases. If you have a set viscosity and a set area then increasing the pressure will yield increases in flow. However, when you have a set amount of force (set by the oil pump) and you increase the viscosity of the liquid you do not have equal flow to the lower viscosity oil nor do you have more.

If the oil has reduced flow it cannot shed heat as fast. I've seen this in action because I have a unique situation where my oil cooler thermostat is stuck open so oil is flowing through the coolers at all times. I saw a 20 degree difference in temperatures when I got off the 20w-50. There are other factors to consider but a temperature change was noticeable.

Under various conditions you will see the same temperature. Don't forget that the cooler system is regulated by a thermostat so it won't even crack till the oil is at operating temperature.

It's the delta (change) in temperature once cooling is available that makes the difference.

Let's not get fixated on Xw-20. I'm not saying that the 5w-20 suggestion by Mazda is spot on. I believe an 0w-30 would best serve the needs of the RX8.

Brettus

iTrader: (2)

end thread

puch96

http://www.youtube.com/watch?v=lYEpU...eature=related

about 4:50 into the video.... recomended 0W20 Golden SL

olddragger

iTrader: (3)

flash---so the oil pump is not volume driven? I dont understand that. The set amount of force on the oil pump you mentioned--what is that? I would think that pressure is the force? Pressure and volume is inversely proportional when viscosity is the same but when viscosity thickens or thins the pressures required for the volume changes. If the volume was reduced you wouldnt see a pressure increase.--right?
olddragger

nycgps

iTrader: (1)

we should.

rofl. they changed it ?

Talk about failed Mazda ... no wonder your rotary is not selling. you **** yourself up.

ASH8

Flash....

I have read your comments on this before, you are talking about the OIL Coolers and an allege thermostat, I think you said these were Internally concealed in the oil coolers themselves.

Can you point to where you found this information from, it is not that I do not doubt you, however I am not sure I believe your source or reason.

Why I say this is we are still in Winter (Down Under) and when I start my stone cold 8 I check the OIL Coolers outside with my hands and within 20 seconds or so I start to feel the oil coolers get warm, within 90 seconds or so they are getting hot.... this is obviously from the engine oil passing through them, so how would any kind of thermostat be in operation here.

Flashwing

I'll have to do more checking into this and see what the actual information is. It's something I've spoken to a couple local people about who I trust. It makes sense (in my head anyway) for the oil cooling system to operate in the same fashion as the coolant system with having the ability to regulate the temperature of the fluids.

The issue that I have been having is previously my oil temperatures used to remain around 180 degrees with the coolant as well. Now during the winter time I end up having oil temperatures as low as 150 degrees. This is with around 40-50 degree ambient temperatures.

As a result it also tends to drag down my coolant temperatures as well. During the winter my coolant temps at cruise stay around 170 to 175 degrees.

So the end result is the oil and coolant not coming up to operational temperatures.

I've not had a chance to dismantle the oil coolers or check any of the parts. It's a project I've been putting off until it starts to get colder outside.

Since the RX8 must be designed to operate in various climate conditions, I don't see another way Mazda could regulate internal oil temperatures without having some method of closing off the coolers.

ASH8

Yeah, to be honest I really have not heard of them before in a Mazda, I was only at my dealer a few hours ago talking on Many interesting issues, I should have asked James, he has been promoted to chief Rotary Man, and in fact was offered a job at Mazda Australia Technical, but does not want to move interstate, he is doing a lot of good work at the retail level for RX-8 customers.

Anyway, perhaps this may be a reason the Rear Oil Cooler splash shields have only small air passages to regulate oil temps via air flow in a very crude fashion????

ASH8

BTW...I can't see any external type of thermostat located on the Oil Coolers themselves (had a good look at mine). IF there is one (IF) it may be internally concealed...

Sorry mate, But IMO I can't see there being one or two, why do my oil coolers get warm to hot so quickly?

I have done a search for Thermostats on my EPC, and nothing in this area at all.

Flashwing

No you are correct that it would have to be an internal thermostat. I took a quick glance at the service manual and there's no mention of any external thermostat.

If there is one it would only have to be located in one of the coolers since they are ran in series. I'd have to look but off the top of my head I am unsure if there are differences between the driver and passenger side coolers. If so, one of them might contain the thermostat internally.

Either way I have to look into this because the behavior of my oil temperatures during the winter time isn't acceptable. Running between 140-160 degee oil temps isn't good.

ayrton012

Maybe you don't believe me anymore , but here is the link:

https://www.rx8club.com/showthread.p...ler+thermostat

It's strange that your II. gen coolers are warm so quick after cold starting. Maybe Mazda changed the opening temp of the coolers. As I know earlier in the RX-7 coolers was 60C temp, not 90C.

Flashwing

Nice find! That might have been one of the threads I was given as a reference. I couldn't recall if it was an external thermostat or not. IIRC, an external thermostat would have to be used if the coolers were upgraded to something not OEM.

Mazmart

iTrader: (12)

Yes, Mazda has always used thermostats in their oil coolers as far as I remember. You used to be able to mod them by adding shims to make them stay in a non bypass condition. We've done this as a safeguard since it's quite possible for them to fail in closed position (Bypass). This has been known to occurr in the FC chassis on it's eccentric shaft oil bypass so we modify that as well. The RX8 uses the same N326 thermo for it's eccentric so we mod that on every RX8 engine we ever build.

That thread about the change of temp (Upward) for the RX8 cooler thermostats was an interesting one that went off course.

At some point I will share more of my opinion on good oil choices for the Renesis in relation to the specifics of this current thread.

Paul.

ayrton012

Thanks the informations about your mods. I always thought about is the N326 thermo a reliable part? My other fear is that the oil cooler's thermostat stucks in bypass, so "good" to hear that it is possible.

Flashwing

Paul! I was just thinking of PM'ing you in hopes that you would have something to contribute so I'm glad you and I were thinking alike this morning.

I would greatly welcome any input you might have. Also thanks for confirming the thermostat presence inside the oil coolers.

9krpmrx8

iTrader: (46)

Paul, when you say you mod the thermo, what exactly do you mean, mod it to stay open or open earlier? Thanks.

nycgps

iTrader: (1)

it it fails, 90% of the time it will "stuck" at "bypass" position. not good.

Mazda did this for one reason ---- emission. They want(need) to get the oil to get into Operating temp ASAP.

Its the same idea as thermostat for the coolant.

Most engine rebuilders will install thermal bypass pellet on new rebuilds to avoid this "might get stuck in the future" problem.

nycgps

iTrader: (1)

if I remember correctly, the cooler's bypass is set at what, 92 Celsius? right ?

9krpmrx8

iTrader: (46)

Ah hah, I see.

ASH8

Interesting, Why is it on my Series II, from a stone cold engine I can feel my coolers getting warm to hot quite quickly.
And it is Cold enough outside for my Air pump to start up.

ASH8

BTW: All Rotaries from 1985 FC RX-7, to FD, and FE have this exact same eccentric shaft pellet.

N326-11-D15 Pellet
N326-11-D17 Spring

rotarygod

I use the oil cooler thermostat on my '90 RX-7 as an oil cooler drain plug when I change the oil. It's the only plug on the bottom.