JonsToy

Is there a certain procedure to drain the oil coolers and lines? The best I've ever done is to jack up the driver's side (American) which drained about 5 quarts from the pan drain plug. But I think it still leaves about 3 quarts of used oil to recirculate in the system.

TexasKyle

A couple of oil changes ago...I messed up and didnt realize the washer wasnt on the drain plug. Didnt notice it in the oil pan until I had two new quarts in. I removed the plug to reinstall the washer and was amazed at how black the oil coming out was. This was the two quarts I had just added coming out, and it was pitch black. Since then...I drain the oil, replace the plug, add two quarts, redrain, and then fill to capacity.

TexasKyle

Hoping this is helping to flush out the old oil. Regardless, I am sticking to my routine.

pcimino

There's been some discussion about flushing the oil cooler. Maybe that's where its coming from?

TexasKyle

Could be...not sure though. I would think that it would just "fall" down through the engine and into pan. I am sure someone with better knowlege of the engines internals could probably answer that question though.

zoom44

quotes from google searches on proper normal operating oil temperatures for autos

" I had never seen the engine oil temperature go over 80°C - most of the time it sat on 60°C."

"According to one manufacturer, if the oil is at a temperature of 125°C, the bearings can be at 170°C, which is enough to make the bearings go to lunch."

"We have determined that on most non-turbocharged engines, this instantaneous oil temperature is usually about 50° hotter than the temperature of the oil going into the engine. If we add the 50° to an engine oil temperature of only 160°, we see that the oil never gets over the 212° mark, which is the boiling point of water. By running at 180° during cruise, the oil should be hot enough to boil off the normal condensation."

"On the high end, the maximum preferred oil temperature is around 200°. This guideline is based on data that show the instantaneous temperature of the oil coming off the pistons for many turbocharged piston engines is about 75° above the temperature of the oil going into the engine. This means that if you are running an oil temperature of 240° during cruise, the oil is actually reaching 315° at some point in the engine. This is OK for a short time, but if your engine operates for extended periods at this temperature, it can lead to coking and an increased level of deposits in your engine."

"Question: 85 corvette 350 mileage: 690. Do I need an oil cooler? My new engine in my vette runs a 230-degree oil temperature. After running at 80-85 for 10-15 miles out of Atlanta traffic, but cools to around 215-220 at 70-75, range is this ok? I took the cheap route and decided not to replace the dirty cooler on the new motor. But, let me tell you, Jasper Engine Company! Hats off to you, this red 85 will smoke! What do you think Bob & Ken?

Answer: An oil temperature of 220 degrees is normal."


"High oil temperature in excess of 240°F (115°C) will break down petroleum oils and cause oxidation, which in turn forms deposits, varnish and increases wear."
etc etc etc.

Go48

One approach might be to drain the pan, replace drain plug, add enough oil to bring the level to above the lower mark (2-3 qts), run the car for a few minutes, drain pan with the drivers side raised, replace plug, fill with oil. That would, at least, dilute the old oil remaining in the lines and cooler(s) and you would end up with a higher percentage of new oil in the final mix.

Personally, I choose to change the oil every ~3K and not worry about the old oil in the system. I've sent off samples from the last 2 oil changes to Blackstone and everything looks fine according to them. I do raise the drivers side of the car when draining the oil and just under 5 qts are required to refill to the full mark. so the percentage of old oil in the final mix is around 40%. That's more than I would like, but the oil analysis doesn't indicate any problems--up to now, that is--with that mix.

two rotors

It is clear that my conversation with GOD is somewhat at cross purposes.If you wish to talk about BULK oil temperatures,measured in the oil pan or after the oil cooler then it is clear that if you had a temperature of 260F, it is too hot.Discussion of corvettesetc don't interest me.
Running thin oil in high ambient temperature conditions can result in excessive foaming which will lead to higher bulk oil temperatures and even more foaming---you sort of get the picture.
We know that the rotary engine is thermodynamically inefficient compared to the best piston engines.This due to the shape of the combustion space and consequent not quite compete combustion.The long surface of the rotor requires oil injection to the interior of the rotor to keep it reasonably cool.Piston engines generally can rely on oil splash from the crank.Some high performance engines have oil spray to the underside of the piston for cooling.But I am unaware of any engine which relies on oil cooling to reject the 33-35% in a rotary.
We also know that combustion gases by pass the the rotor side seals.It is when the these hot gases come in contact with oil mist that the degradation is most severe and temperatures of up to 800F can easily be achieved.
We also know that the blow by gases contain unburned petroleum which when it condenses dilutes the oil and reduces its viscosity.You can smell it.

So what can be done to reduce the hot combustion gas / oil mist interface?
1 You can reduce the bulk oil temperature by adding oil cooling capability.A somewhat expensive option,but one which might be implemented by Mazda.

2 You can use a lubricant which foams much less than the 5W20 recommended by Mazda North America.This might be a fully synthetic oil of the same viscosity rating(Racing Beat somewhere in their experiments confirmed this). Or the least expensive option is to use a higher viscosity oil say 5W30,10W40 or even 20W50.If there is some one out there with a temperature gauge on there oil sump or oil cooler outlet perhaps they can confirm the reduction in bulk oil temperature when using higher viscosity oil.

3.You can change your oil very often--I am using a 4000km interval and the oil still stinks of gasoline.

I shall now wait for a higher God(Mazda NA) to decide on the solution.One other thing my source confirmed that the decision on the 5W20 was based on fuel consumption considerations

zoom44

im not quite sure what you mean but you seem hostile. i dont understand that. you asked how you could have driven all your old cars etc etc. i explained what i know to be true with information from mutiple sources so it would be clearer. you mentioned other cars which is why i included the corvette reference. i included soem celcius quotes so you wouldnt have to do teh conversions. i thought i was being courteous. i am not an expert on oil nor have i claimed to be. i am trying to pass on the information i get when i can. when questioned i try to answer to the best of my ability. They have measured oil temps of 260 degrees in Vegas RX-8s and Jay Goldfard has reported his oil temps (in florida) as being above 240 at times. sory if it wasnt clear what temp we were talking about


thank you for the explanation about combustion gases and oil. wouldnt that be a problem everywhere tho? or is that exacerbated by ambient temps and low humidity? your first suggestion is soemthing we have already talked about. Your 2nd doesnt seem likely since Mazda is dead set against recommending Full synthetic lubricants, but Jay Goldfarb has already posted his results using 20w50(search).

We all are waiting on MNAO of course. the 5w20 and mpg link is already well documented here.

TexasKyle

I just run my up on my ramps. Makes for lots of room underneath, especially with my sloping driveway. Hadnt considered adding oil, running, and redoing the oil change. Mayne I will try that and see what comes out. I am using Castrol GTX, so at least its no as pricey as the Synthetics.

bxb40

Just to clarify: engine oils have a boiling point higher than 200 deg C, regardless of grade. It is the base stock boiling, not the viscosity modifier (the last gives the grade - more you have, thicker the oil). So purely on temperatures, your 5W-20 does not boil off. However, oils foam - hence contain antifoam compounds. Different brands use different compounds. All those properties (and a lot more) are part of the oil specification: foaming - divided in 4 stages, oxidation resistance (TFOUT test), deposits under oxidation (TEOST test), drop in viscosity after 20 hours oxidation breakdown, boiling point, flash point, etc. Now, I doubt those tests developed for piston engines fit well with the Renesis, but they still provide the best approximation - so a foaming oil will still be foaming, and a high deposit oil will still have high deposits. And to the person stating that viscosity does nothing for engine protection - you can't be serious! All those metal moving parts "float" on oil films - make it too thin (wrong oil grade or too high temperature or broken down oil or foam in oil) and when the asperities from the two moving parts start touching, your engine is dead. Lubrication 101 :o)

two rotors

Sorry if my hostility offends you.I strongly disagree with the absolute statement you made "no one should be concerned about 5W20."A statement made without any qualification as I read it.There are good reasons to be concerned under certain conditions.It is clear that a heavier oil will provide better protection for a rotary engine under some conditions.
I was also offended by the way you jump on people who try to contribute.

clydejmuggs

I welcome your contribution and I really don't think Zoom44 was trying to debunk your experience and knowledge. There have been dozens of ideas posted in this thread and getting to the bottom of the real issue is what we need to focus on.

1) How many engines are actually sitting at Vegas dealers

2) How do we get more airflow to the cooler(s)

3) Are the dealers there using the same brand of oil and if so what brand

4) How many of these cars are "post flood" cars?

Lets sort out a few of these questions and have a beer.

Cheers.

zoom44

aha! that wasnt me that said it!!:D i said the 260 degree bit which you said soemthing like "your in the US so thats farranheit alot of times the oil sees higher temps than that". i thought you were saying 260 was not hot and i was just trying to clarify why i believe 260 to be bad. which apparently we were talking about 2 different measuers of oil temp as you explained - i was talking "bulk" oil temp and you were not.

however i did not make the statemnt about 5w 20 in fact i have stated several times that i think 5w20 is not correct oil for these hot areas and agreed with several others that 20w50 would be better suited.

so you confused the person who said that "no one should be concerned about 5W20" with me. while he and I agree on many things we are 2 seperate people and on this one i disagree with him as well. however i am still not hostile about it.

hope that clears it up. re read page 21 from your post #310 and you'll see i was even thanking you for checking into it. sorry if you thought i was "jumping on someone who wanted to contribute". i value everyones contribution to this puzzle

crossbow

Exactly. If oil temps are spiking in the 260-280F range...dino based oils will not survive, regardless of weight. However most "true" synthetics (group IV and V) have significantly higher temp ceilings. I do believe redline's tech's indicated that their 5w-20 oil could withstand temps of 300F without breaking down.

Of course running synthetic is just a bandaid to the real problem...lack of oil cooling...but I am just interested to know if ANY of the engines that have had problems were running synthetic. (Running synthetic being a good thing in this situation).

Btw, the thicker oils would have even higher oil temps. Going from a 5w-20 to something like a 15w-50 can increase oil temps as much as 20-40F depending on the particular application.

Has anyone thought to wire up some small radiator fans to their oil coolers? The primary issue IMHO, is the rx8 oil coolers sit away from any type of active airflow when the car is sitting idle, or at very low speeds (traffic). Some simple hi-tech fans like this...

http://store.summitracing.com/egnsea...842+4294865165

Might do the trick. (That fan is just an example, I don't know if its any good or not).

Some of the more "overseeing seers" have mentioned that perhaps moving to an oil cooler which sits in front of the radiator/condensor would do the trick, as then the radiator fans could provide airflow at idle or low speeds. Didn't one of the rx7's have something similar to this?

RX8world

crossbow...i was thinking the same thing the last couple of days...
i told that to my mechanic and when he return from his vacation will start fitting one.
My 8 is one of the first production group..april 2003.It came from japan with one oil cooler although it's a 6spd 246 bhp.I live in Cyprus.It's the third summer now and i didn't have yet any problem.Max temp here is up to 40 celcius.I use semi synthetic Texaco Havoline Energy 5-30.I change my oil every 3000km maximum.Mazda corporation here didn't receive any recall.I know that because the general manager is a friend of mine...he told me also that he haven't seen yet any 8 with these problems.Note that all the 8's here come with one oil cooler,at or mt.
We've checked the car for problems like gas tank-lower ball joint etc but nothing.My car has 20000 miles.
I gave all these informations because i try to help the situation.
Is oil viscocity THE problem? OR maybe the CLIMATE of each country? OIL Coolers?
Having 1 oil cooler or 2 will not save the engine if you are in a traffic BUT , an oil cooler fan may give a solution.EVERYTHING works better thanks to the fans : a computer, an air condition compressor, freezer ......etc etc etc.

Dinhx8

Thanks for all these posts guys, very helpful-
Earlier in the thread, Rob mentioned Magic only had 04s, no 05 yet. Anyone have thoughts on that? Given their mechanical similarities (identical), not sure why this is happening? or is it just coincidence, or a mileage wear issue I wonder...

MadDog

There's just fewer 05's out there, I would guess. Even if they have the same likelihood of the problem, there will be fewer with the problem.

two rotors

I spent a few minutes over lunch looking at information on Mazda's Parts system.What I found is attached.But maybe summarised as follows:
1.There are 10 new engines(MT) available in North America.

2.New engines for AT cars are expected 22August05.(Don't hold your breath.)

3.The last change to apex seals was at VIN---111588,which must have been
abouy July 2003.

4There was a change in rotors at VIN---102193,probably a month earlier.

5.The oil metering pump was change at VIN---100112,again probably June 2003.

6.Oil pick-up/strainer was changed at VIN---100470,about the sane time as above.

I could find no other significant part no changes.I see no sign of any magic bullet coming other than using higher viscosity oil.

two rotors

And the remaining attachments.

zoom44

hey did you read my post last page? you werent being hostile to me:D. anyway the oil pump part number -c is the higher flow one we talked about here and in this thread

https://www.rx8club.com/showthread.p...ber#post898016

since racing beat has a modified version as well i asked them about tit back then and they said

anyway like i said they tried on a few but arent recommending it at this time for this issue. i think but havent confirmed (havent returned my email ) that the issue was the hot thin oil was the reason for losing seal and not quantity of oil. like i said tho that is my opinion unconfirmed right now.

like you say they dont have any new part in the pipe for this yet. they are definetly going to have to suggest a higher viscosity with the new engines. they will probable install a second cooler as well. im sure they have already taken a look at the oil being used in Vegas and Lubbock etc etc to determine if it is a brand issue.

zoom44

nice to meet you two rotors

Nubo

YES.
Yes.
YES.

I've been using Mobil1 5W30 since the first change.

Nubo

Problem #1 may argue for a separate oil resevoir for the oil injection -- inject clean, undamaged oil.

rotarygod

That has actually been the whole point I've been trying to make about running a thicker oil. It is a bandaid.

Maybe a thicker oil will last a little longer than a thinner one but it isn't a cure for the problem and shouldn't be treated as such. This also assumes that all oils of the same weight break down at the same rate which they don't. I guess if people just want a little more assurance then they could run a true synthetic like Royal Purple, Amsoil, Redline. etc of say 20W50 since it might not break down as fast but at these high temperatures it will still happen. If all you are worried about is "later" then go ahead and use this combo. I'd still rather just "fix the glitch" (for all you Office Space fans) and use the 5W20.