ASH8

I think 9krpm wanted a pic of the Oil Cooler feed/return lines in a S1 RX-8..
Return line in oil filter body (red)
Feed line from oil pump (Blue) front cover.

PhillipM

It doesn't need to heat soak the oil in the pan, our sensors are straight after and straight before the oil cooler, in the lines...

dannobre

iTrader: (3)

And how long does it take for the driver to notice the change in the pre-cooler temp without a flashing light ? And how long does it take to raise the pan temp to the pre-cooler original temp?

Betting it takes longer to notice than it does to heat up the oil

9krpmrx8

iTrader: (46)

Great pic, Thanks Ash.

olddragger

iTrader: (3)

pic ex is worth a thousand words

http://www.magnet-tool.com/product-i...pplication.jpg
When filter elements are clogged, the pressure builds up and pushes the top plates opening the bypass valve. When the bypass valve open, the oil flowed back to engine without filtration, thus the particle will cause premature engine wear.This is a pic of the flow once its clogged. Unfiltered oil goes in from the sides and comes out from centre of oil filter unfiltered.
Never mind the magnet--i dont use that style. BUT with a magnet in place it is helping clean the oil even if the bypass is open.
You know I got rid of my oil pressure gauge --think i may get it back. I am thinking we may be activating the by pass at high rpm if we are not running a good flowing filter---i have oversize my mobil one filter--that helps a little.
Ash what do you thing we can change out after dropping the pan that will help?
OD

madcows

I certainly wasn't implying that series 1 has sufficient oil flow (maybe it does, maybe it doesn't - I personally don't know), but rather suggesting that the addition of an oil cooler since the FC shouldn't affect the mass flow (and there are varying fluid pressure points throughout the system, so pressure info is somewhat arbitrary). That's not to say I wouldn't rather have a series 2 renesis

PhillipM

Well, seeing as it's a rally car, and there's a co-driver monitoring it, a second or two at most....

dannobre

iTrader: (3)

Co-driver helps I found that driver only it takes longer than that.......

madcows

BTW, a bunch of Evo X MR guys have been using sucker fans behind their trans coolers (similar size to our oil coolers) for several months months now. Those of you who been wondering about the possibilities should perhaps look into a similar setup.

ayrton012

The w50 is not the ideal solution, it is only the solution for the low factory oil pressure. It not solves the problem, only fade it away a little bit.
You have low pressure so you increase it with thick oil, but with the thick oil you decrease the flow, so you increase the temp of the bearing and the oil. Low flow and high temps mean more wear on the oil and the parts.

The solution would be the higher pressure, as they did on the S2. We need a DIY of the bypass regulator changing!

nycgps

iTrader: (1)

increased temp with heavier oil? Hmm, For some reason, my oil temp stays the same. 5w20 vs 20w50. maybe my oil temp gauge is broken? maybe maybe.

The only thing I cared is the result. Im the type of person that belives in "real world results" more than "yada yada on-paper facts"

20w50 works, Its proven from the Rx7 people. fact. it might not be the ideal solution, but its the easiest and hey again, it works. Also(again) the fact here is that 20w50 protections couple times BETTER than say, 5w30. real world fact.

Go ahead and ask other High performance vehicle owners what oil do they use? 5w20? 5w30? hah !

Will the increased oil pressure works for the S2 still remain to be seen, so for the time being. 20w50 is the solution (the easiest solution)

Its around 38 degrees 2 nights ago and my oil pressure havent change much, I guess Im staying with 20w50 all year long. (a good Synthetic 20w50)

Mazda is an auto company, and all they cared is to use something that benefits them the most (5w20) that will last until the Warranty period expires.

Dont forget, its NOT the first time that Mazda messed the engine up. How many times have they released ECU updates ? Im sure way more than most other manufactures did.

olddragger

iTrader: (3)

thicker oil will increase temps --but not that much. At least that has been my experience. Synthetics will run cooler than dino--i also have seen that. None of them get to hot in my car.
I cant speak for others. I do keep my redline to 8K which probably helps some.

What I am wondering about now--- is the filter bypass. During cold startups and high rpms I do wonder if the filter is doing a good job. I wonder if we are popping the filter by pass some. At least I put a magnet on mine--use a bigger filter also--mobil one for me.
olddragger

PhillipM

Fact?!
From who?
You've got oil going through gearsets at high temperatures which is full of detergents, it's going to try to foam up at high rpms.
Guess which oil foams up more, 50 weight, or 20/30w.....

There's a reason top end dampers use oil like water....


It's an opinion, and conjecture, if it was fact, we'd all be running 50w oil.

madcows

I don't see how thicker oil would decrease the flow. Could it increase the pressure at various points in the system? Probably.. But the pump will ALWAYS pump a certain volume of oil at a given RPM regardless of oil weight used.

madcows

10w40 is used in most sport bikes which not only rev at totally insane speeds, but also typically use the same oil for gearbox lube and can avoid foaming. According to amsoil spec sheets, their oil doesn't foam at all. hmmm. While I don't have anywhere near the experience many of you do, I'll stick with 40, or 50 weight.

PhillipM

They are also typically low-detergent oils and have specific makeups, especially friction modifiers, to work with the gearbox and wet clutch, completely different oil.

If you don't believe me, put a normal car oil in a bike and see what happens.

TZ250

I believe this is incorrect. Pressure is resistance to flow. Pump is designed to move fluids in a certain range of viscosity. At some point the resistance to flow will overcome the pump's design capability and the pump will simply cavitate and move nothing until the pressure is relieved. At a given RPM the pump will move less of the higher viscosity fluid. Flow confers lubrication, pressure does not. If you increase pressure on the same viscosity fluid, flow will increase and so will lubrication. That is the key connection between pressure and lubrication.

As Flashwing? said in a previous post (and I paraphrase), if all we needed was more pressure, we'd all be running 90 weight.

madcows

As far as I'm concerned, the primary difference between car and bike oil is the friction modifiers as you state. Car oil would most likely be fine in a bike with a dry clutch, and bike oil should be fine in a car. At any rate, I doubt it's the friction modifiers that cause foaming anyways. With that said, using good oil, I doubt that there's any significant issue with foaming.

madcows

Your description would be true of certain types of pump - not positive displacement types, though. It will flow any fluid (regardless of weight) at the expense of 1) power needed to pump thicker fluid, and 2) possible mechanical failure due to stresses associated with pumping of such fluids. It is doubtful that either of these issues are significant between typical 5w-20 and 20w-50 oils.

If you took an oil pressure gauge, and was able to attach it at various locations throughout the oiling system, you would see so many different pressure readings. We want mass flow, while pressure is just a function of this by nature.

mpsii

So... after all this reading...

Are we supposed to do 5w30, 10w30, 5w40, 0w40... what?

PhillipM

Actually, thicker oil = more cavitation = less flow, he is right, if the oil gets too thick the cavitation can actually get to the point where a gas bubble suddenly forms and no oil flows at all.

It's the same reason I don't believe techs that tell me there's no foaming in oil...
Even if you pressured the entire system system to 500psi, there'd still be some level of cavitation, as it is, it's in a slight vacuum.

TZ250

I am now officially over my head in terms of fluid dynamics of positive displacement pumps. I do recall in all my racebikes that the positive displacement oil pumps in the gearboxes (they were separate from the crankcases) all had bleed-holes to relieve over-pressure.

9krpmrx8

iTrader: (46)

Read some more, there is no clear answer. You have to look at what type, condition, etc. you drive your car in and then how long you want it to last and then go from there. Personally I think 0W-40 is the perfect balance.

ASH8

Just to simplify matters..

The RX-8 (S1) Oil Pump is the exact same one as used in the 1985 FC RX-7, (Mazda calls it a "Force-Fed Type" of system) I believe the "recommended" oil weight then was 15W40.

The Australian RX-8 (S2) Japanese Printed owners manual says you can use any oil weight from a 0W50 to a 20W50 depending on weather/climate.

All the engines internals are the same for each model world wide.

On Series 1 RX-8's like all other previous rotaries the Oil Pump has a By Pass Valve and also one at the end of engine, so the pump itself can obviously put out a higher oil pressure, BUT, the relief valves maintains it to a level of 64-71 PSI (156 PSI for Series 2 RX-8).

IF you want to increase Oil Pressure in the "system" it is best to alter both pressure springs in the oil pump valve and rear iron housing valve.

The series 2 8 is a different Oil Pump with design features not seen before in a rotary.

nycgps

iTrader: (1)

so do I need to pull the API spec table out again ?

and you might want to explain why we're seeing bearing wear then (going back to square one) that has never seen before in the Rx-7. Yes, all got the SAME bearing