9krpmrx8

iTrader: (46)

Hmm, I'll have to take a picture.

N8theGr8

ASH you should hop over to the "used oil analysis" thread and check out the results of RX owner's oil tests. Lots of interesting info, including many of the variables you listed.

madcows

Very interesting thought. At low to moderate RPM, the discrepancy in viscosity is probably irrelevant, but what goes on in the upper rev range @ street temps is unknown.


GeorgeH, the Redline 5W-30 is probably really nice. And while good synthetics take much longer to degrade than dino oils, I'm still weary of only replacing half of the oil systems capacity with an oil that's on the lower end of this typical motor oil viscosity.

oldragger - I thought there was a thermostat in the oil coolers?!


Too.. many.. things.. to.. consider... Brain.. about.. to.. ASPLODE!

GeorgeH

iTrader: (2)

Again, the point I've been making is Redline 5w30 is not thinner than dino-based 15w40 or 20w50 under high temp, high shear conditions. At least, according to the SAE specs.

To be clear, SAE requires both 15w40 and 20w50 to have a HTHS viscosity of 3.7 (can't remember the units). RL states that their 5w30 has a HTHS viscosity of 3.8.

On the other hand, regular dino 5w30 (and all other flavors of xw40) has a HTHS in the 2.x range.

So, the RL 5w30 starts out thinner at startup, but converges to the same value as "SAE standard" 20w50 at 150C.

Of course, it's difficult to know if the oil experiences high shear rates at 150C in the bearing, but if there ever was an engine that could do it, it would be ours. But if you assume for a moment HTHS is the right spec to look at when choosing your oil, and that you want the 20w50 value of 3.7, then it becomes a question of which oil you'd rather have spinning around before it's up to temp, and which oil will loose HTHS viscosity sooner - a thick 20w50 dino oil, or a thinner 5w30 synthetic. I think the synthetic wins on both accounts.

But hey, I admit I'm reaching here. Like everyone else, just trying to make sense of everything. There will be different conclusions reached, as it should be. Me, I'm driven by the fact that my commutes are short, and my poison of choice is autocross, where it's nearly impossible to get the oil fully up to temp before the first run, so I like the idea of an oil that is thinner at lower temps but still protects when it gets hot.

madcows

*goes to read up on HTHS*

ayrton012

Almost every words are true from you in thsi quote, but you are wrong about the thermostat. There is a thermostat (194F "bypass valve"), integrated in the oil coolers.

Otherwise you are true, and I can add to your words, that very important that there is the oil pressure regulator e-shaft pellet which highly regulate the oil pressure (PSI/RPM) below 140F oil temp. Strange, but the water temp gauge can be at hot position, before the oil gets 60F. IT IS THE MOST DANGEROUS SITUATION, THE OIL PRESSURE AND FLOW ARE VERY WEAK, WITH OPENED E-SHAFT PELLET!
If someone revving the engine under 60F oil temp, kill his engine's bearings quickly.

Mazmart

iTrader: (12)

Which is why we modify the eccentric thermostat in EVERY engine we build.

Paul.

PhillipM

Well seeing as I borrowed my header design from the old a-series Mini racing engines, there's something else you fans of 20w50 can borrow too, the A-series uses a stacked gearbox below the crank, which means the gear lubrication is done by the engine oil, and hence has to operate in similar conditions to the rotaries stationary gearset.
This means lots of EP and foam-depressent additives - but with a dry clutch, unlike most bike engines, so they can also include lots of Moly/Titanium DiSulphide and other solid lubricants.
Millers makes an oil specifically for this purpose, it may be worth a shot for those running 20w50 (they don't do it in lower viscosity, mini internals are fairly old tech. with large clearances and lots of crank whip), although the cold flow is at the very bottom end of the 20w scale - it's nearly a 15w.

olddragger

iTrader: (3)

i have heard about the oil coolers thermostat but in the real world i have not found that it works? I monitor the oil temps at the oil filter plate--so that means that sensor is fed by the returning oil from the coolers. My coolers also become warm much before the 190F range which to me indicates flow.
Please correct me if I am wrong.

Phillip--the reasons you mentioned is some of the reasons I like deisel oil.

And like Paul says--this is another reason I got my engine from them!
OD

9krpmrx8

iTrader: (46)

The thermostat I bought for my single oil cooler is a 180 degree unit designed to keep oil temps under 200 degrees.

GeorgeH

iTrader: (2)

http://www.bobistheoilguy.com/forums...501#Post530501

http://www.bobistheoilguy.com/forums...=530356&page=1

Good places to start. Somewhere in the first thread, I think it is, is the link to the SAE table of HTHS viscosity by oil weight.

olddragger

iTrader: (3)

9K if the oil is not flowing through the cooler until 180F --does it have a bypass that supplies it back to the engine ---right ---duh?
is it up and running yet?
findings?
OD

ASH8

This issue of Oil Cooler T/stat has come up before, I was a skeptic, until Paul showed the FC's oil cooler pellet, which is a replacement part made by Mazda...I never sold one.

From FD RX-7 on-wards Mazda Parts show no available thermostat or pellet available, but, I think Paul proved there was a Thermostat there...of sorts.

But, like OD, my S2 Oil Coolers are starting to warm up within 30-45 seconds of start up?
Aryton also posted info from Mazda "Germany" manual that said they opened at 95C!...
But I have not seen any info about the coolers since...(might just go an check my WS Manual).

As the Oil Flow is slightly different in S2's and the Oil Coolers are a S2 Specific by Part Number, I am considering Mazda may have either lowered or changed the Thermostat, or are these just a Pressure Regulator as my Oil Circuit does show a By Pass at the oil coolers.

So why would it be by passing Oil that is NOT Cooled...that is all it can do?..

IMO it would be by passing OIL if the oil cooler became Blocked? similar to an Oil Filter??

Come back..

Workshop Manual says Nothing...Just how to remove and replace Oil Cooler (s)

9krpmrx8

iTrader: (46)

No way my coolers are heating up after 35-40 seconds. It was in the low 40's(F) this morning and it took nearly six minutes for the oil to get to 70 degrees.

ASH8

It might be 60 seconds, but, I a not talking Monitoring from a dash guage, I am talking standing outside of your car and touching the Cooler itself......

So if there is a thermostat, how are the Oil Coolers getting warm within a minute, there has to be some oil flowing though them (which is heating the OC).

Even OD says his S1 OC get warm quickly and I have an S2??

BTW: It is going to be 45C here Today 113 F, that will test my cooling system out, will be reading ODB info too.

PhillipM

Is the thermostat in the coolers themselves?
If it's is there'll be the heat transfer through the body from the thermostat.

GeorgeH

iTrader: (2)

Just tried this. On my '04, after two minutes of idiling on a cold motor, I could feel a slight increase in the temp of the oil coolers. At 2.5 minutes, it was obvious. Outside temp is about 45-50F.

So, something is warming the coolers.

9krpmrx8

iTrader: (46)

So that would mean there is no thermostat in the coolers right? My oil thermostat routes oil back to the engine until it reaches 180 degrees.

Mazmart

iTrader: (12)

There is definitely a thermostat in the cooler. It just bypasses the main cooling section until it's set temp.

Paul.

Flashwing

I've long wondered if my cooler thermostat is broken because without my right mud guard I believe the coolers are preventing my oil system from coming up to full temperature.

Part of the reason why I've stuck with the 20 weight oil this long is I'm only seeing about 160 degrees of oil temperature going back into the motor. I suppose that means it's warmer at the cooler itself.

Is the cooler thermostat set for 140 degrees? I know Ash has commented on this previously but I'm unsure where I saw it.

Mazurfer

So I'm a little slow here...................so if this thermostat in the cooler went out(or stuck), then you could theoretically have significantly less cooling in at least one cooler(and maybe even both coolers if both were bad)?
All the more reason to monitor oil temps.

olddragger

iTrader: (3)

ii do remember someone posting a pic and detailed info about the oil coller thermostat. But it aint working right.
Takes oil much longer to warm up than coolant and hect if i am on interstate on a less than 60F day--oil never gets over 155F or so and thats not warm enough. I wonder does it allow one cooler to work and when a temp is reached it opens the other cooler? Just a by pass type?
OD

Flashwing

Ok, see this comment makes me think that my system is working fine. Honestly anything below 85 degrees here in Phoenix I am unable to maintain operational temperatures without some heavy loads. At cruise I'm always below 180 degrees with oil temperature going into the motor and if I'm 160 degrees or below my coolant starts to lower as well.

9krpmrx8

iTrader: (46)

So what exactly are you touching on the coolers ASH? yes under normal driving conditions I have not really seen temps over 175 and that is with a few moments of pushing it a little hard. This weekend I will get specific data.

madcows

Just a week ago I started my car (was around 40 degrees F give of take a little) and let it idle. After about 4 minutes, the oil coolers were almost too hot to touch. I'm considering getting an IR temp gun just to check em out every so often. If these thermostats are half ***, wouldn't it be better to let the car warm up standing still?