eage8

iTrader: (9)

Very interesting thread.

I currently use Castrol GTX 20w50 with a mazda filter...

I change my FCs whenever I feel like it pretty much, (usually around 1000-2000 miles) because I don't drive it everyday.

I definitely do worry about the blow by, my oil definitely smells like gas, but I've never had it tested... I should probably do that.


I definitely can't justify running something like mobil 1 or idumitsu, and changing it every 2k, it seems like a waste.

and as far as cold starting... I would probably say as long as it's not really hard to start, you're fine. the bearings will probably outlast the apex seals anyway.

Aeka GSR

iTrader: (4)

Well that's not where the problem is, the problem is after the car has started the bearings are waiting for the oil. By cold start, I mean the car hasn't ran in 6 hours, not that it is cold out.

skir2222

Why not just follow the FSM recommendations?

2007 ZX-10

already covered

2007 ZX-10

I didn't hear anything that convincing, except some guy who posted a link about ferrari engines if bearing clearance was such a big problem, alot of us would have spun a bearing long ago...apex and side seal clearance sure the heck isn't a reason, if anything, the thicker oil film will theoretically seal better and increase power

2007 ZX-10

my opinion is that fuel dilution reaches 2-3+% so fast in these engines that you literally can't change it fast enough, unless you're one of the crazies on here who changes his oil every 500 miles or something

c'mon folks, how long does it take for the oil to look black, roll off the dipstick like water, and smell like gas? not very long at all!

and the fact that there aren't more oil related failures in these engines is a testament to how simple and robust the basic design is, overlooking the fact that, like a two stroke, separation of the intake, combustion, and exhaust cycles sucks, which is why there is so much blowby, and why the gas mileage is so poor

skir2222

How is this already covered? I replied to rich's post back to me on that, and it hasn't been answered yet.

What is being changed inside the engine on a 350-400hp motor then a stock motor? Still the same seals, can do that hp level on stock ports, oil pump isn't changed in anyway, and neither is spark. We add more fuel to compensate the added airflow coming in and out the motor, but what has changed internally to were we should use a different oil?

skir2222

There is nothing we can do about this, it's very common with this motor. Nothing's perfect.

2007 ZX-10

the point is Mazda was and is a collection of human beings like any other manufacturer, they got alot of stuff wrong on this car, and they may have underestimated the fuel dilution, or just figured it wasn't a big deal

it's interesting that most n/a rotaries don't seem to have near as severe dilution of the oil

skir2222

Your not going to find a bulletproof car, overtime things will break and fall apart. Our cars are over 15+ years old

We are forcing air into our motor's that's the difference right there and is more likely assisting in the dilution of fuel in the oil

skir2222

Idemitsu makes oil specially made for rotary's. They offer 10-30w and 20-50w.

The FSM states at 3000 rpm's you should have approximately 50psi of oil pressure.

So those of you who do run 20-50w and have a oil gauge with a readout, does your gauge go over 50psi at 3k rpm's?

How about people running 10-30w with a oil gauge with a readout?

Aeka GSR

iTrader: (4)

Each should make their personal choice on a few factors:

RPM: High RPMs need volume, an oil manufacture I posted earlier recommends thinner oil for higher RPMs.
HEAT: If you oil temps are hitting over 300F than a thick oil should be considered and override the high RPM rule, more HP = more heat.
CLEARANCES: wide clearances need thicker oil to maintain oil pressure, tighter clearances require thinner oil since the pressure will be high enough. This also offers better cooling.
FUEL DILUTION: Stay up on your oil changes if you want to use thin oil, 3% ain't that much. We really do need actual weight numbers though, I'm just going off old math as I stated earlier.
COLD START: once an engine is started a thicker oil will take longer to build pressure (watch your gauge). Most of your wear comes from this alone.

Make your personal choice based on the above.

2007 ZX-10

not a rotary specific source, and there is no evidence to indicate a 20w-50 synthetic doesn't provide ample "volume" (flow) with rotary specific clearances

this isn't a Honda engine and most people have rebuilds, anyway

3% is ALOT according to most reputable sources, it should be ZERO (or near zero)

what? when cold, higher viscosity oil results in significantly higher oil pressure immediately, which is why I watch the pressures and stay out of the throttle until the engine is completely warmed up and pressures drop back

cold start wear occurs with 10w-30, too

I did

http://www.woodsbrosracing.com/amsoil/tro.htm

Aeka GSR

iTrader: (4)

doesn't need to be rotary specific. The proof is basic fluid physics.

Yes the tolerances may not be as tight as a honda and I do recommend people take that into consideration, but if your pressure is good and you aren't getting the oil too hot, I'd still look towards a thinner oil.

I haven't seen actual numbers of viscosity yet at this level, so all I can go off of is what I learned in a class. Until someone shows us actual viscosity numbers at 3% this is a huge gray area for us. Yes we would all like to see zero, that is a no brainer.

Just no. Maybe you didn't understand my explanation. The time it takes for thick oil to start building pressure vs a thin oil to start building pressure the thicker oil takes longer. This is basic automotive stuff.

I never said it didn't, but it occurs for a longer time with 20w-50 weight as explained above.

zenofspeed

iTrader: (1)

All this debate over which oil to use and how often to replace it is pretty much irrelevant IMO.

Each car is different. Each person's driving style is unique. And people live in a wide array of climates. I can't accept that there is a "Best Practice" that would blanket all FD owners regarding oil viscosity.

The fact of the matter is: If you want to know what oil to use, buy an accurate oil pressure gauge, determine your desired operating oil pressure, and adjust accordingly.

Say your oil viscosity drops due to gasoline contamination, that would be detected through your oil pressure monitoring, and you could replace the oil then. It is GENERALLY better to use thicker oils in hotter climates or under heavy engine use (like an HPDE). But that generality must be confirmed through oil pressure measurements.

Another widely accepted notion is: change the oil often. That is the key, and about x1000 times more relevant to engine health than guessing which viscosity is best.

But if we are going to talk about it:
I have read some very in depth articles concerning oils. The main point of those was: "95% of all wear occurs on startup, therefore run the thinnest oil you can, and run oils which have higher rates of retention to metal parts." Some synthetics have been proven to hang to metal much better. You can also get those synthetics in 0w weights which are thinner when cold and will coat the engine more quickly at the point of startup.

I take all of it with a grain of salt though. And I just change the oil frequently and don't worry about it.

2007 ZX-10

again, note the UOA posted on p. 1...after 1,000 miles, it's the equivalent of a 20w

we're talking oil pump pressure, right? when I start my car cold, it's immediately over 100 psi, thin oils generate less resistance, ergo less pressure

2007 ZX-10

it's very relevant

these engines are fairly similar: turbocharged rotaries operating at high combustion chamber temps, with excessive fuel dilution of the oil, up to 10%

actually, that's an antiquated concept, more and more people using synthetics are running them 5, 10, 15k and more miles between drains, with plenty of TBN...unfortunately, you can't do that with our engines, and it stinks

the oil in my S2000 looks great after 5k miles, it doesn't smell like gas, and it doesn't have the consistency of water...it regularly sees trips to redline

start-up wear is still going to occur, regardless, even with a 0w-20, and the viscosity protection isn't there to withstand turbo rotary abuse

zenofspeed

iTrader: (1)

I read and re-read that post, but I'm not understanding any "point" to what you just posted.

You just said that the concept of "changing the oil often" is antiquated. E.G. "your s2000 goes 5k miles between changes"

But aren't we talking about turbo rotaries (not honda 4bangers) that contaminate the oil with gasoline and therefore decrease the oil's viscosity? Wouldn't changing the oil often be the soluton to this dilema?

Using higher viscosity oil in anticipation of dillution does not seem right. That just means your oil pressure is too high to begin with. If the oil is going to be contaminated, then it doesn't matter if you put in some fancy synthetic or castrol gtx does it?

What does matter is that you change the oil often enough as to reduce the contaminants.

Regarding start-up wear:
Of course you still get start-up wear. The idea is you get LESS wear the faster the parts become coated in oil. Thinner oils achieve this faster. Retention is also a factor, especially when the car has only been sitting overnight. Would you rather run your motor for 3 seconds without oil or 1 second without oil? Not that it matters! You will be rebuilding the rotary before start-up wear is even a factor.

2007 ZX-10

depends how "often" is good enough...as I already stated, the oil gets contaminated so fast in these engines that a dino 10w-30 is basically shot after less than 1,000 miles, and changing your oil every 1,000 miles is nuts imo...I run 2,000 miles on Mobil1 15w-50

what is "too high"? plenty of people have run 20w-50 in these engines for years...nothing happened

the superior properties of synthetics are well documented, fuel diluted or not, let's not turn this into another tired dino vs. synthetic thread

how much less? is it a quantifiable difference over one year? I doubt it...more important is protection against cases like Brian's (BNR turbos) car, which suffered an oil related failure during operation

I don't think there is any evidence to suggest a 10w-30 synthetic "sticks" to metal surfaces any better than a 20w-50 synthetic overnight

exactly, so I'm not sure why you're arguing the point...after 1,000 miles it's probably the equivalent viscosity of a 30-40w, anyhow

Monkman33

iTrader: (28)

Screw it. Everyone get an accusump. (to eliminate cold start wear)

Run 15w-40 (because its between 10w-30 and 20w-50)

and flip a coin between synthetic or not. (because its YOUR car)


I mean... really?

dgeesaman

iTrader: (7)

Is this a poll or a lecture?

wrankin

Is this absolutely true? I have heard anecdotal evidence that some of the track folks who are running catch-can systems with fully vented oil pans are not seeing the fuel dilution problems that we experience.

Thoughts?

zenofspeed

iTrader: (1)

It's ok with me that we see things differently. But anyway...

I don't think we have enough hard data. Just one instance, on one car. The amount of blow-by varies between engines and driving circumstance. As I said, you can determine how often by monitoring your oil pressure precisely.

There isn't some specific threshold. The oil will function as oil within a wide range of viscosity and pressure. If you are concerned over every inch of horsepower, then knowing your precise oil pressure is the only way to determine what is "too high" for your desired application. People have also run 10w-30 for years and nothing has happened. what is your point?

I'm simply relaying information from what I determined were valid and objective sources.

I'll try and find the specific article as I think it would be a very good read for anyone who may want to learn more about it. But in short, yes, they claim it to be quantifiable.

the hypothesis is this:
Assume your start-up is 90% of the wear on the engine. Then assume that on start-up it takes 1.5 seconds to coat the entire thing. But if you used a thinner oil, it takes 1.0 seconds. You just reduced the start-up wear by 33%, and 33% of 90 is 30. So in that hypothetical situation, you reduced overall engine wear by 30% simply by using a lighter (when cold) oil.

I have never seen documented properties of either syn or non-syn when diluted with gas, as you are implying. Can you show me where this is?

You are mixing two separate points. I'm sorry it wasn't more clear. Synthetics hold onto metal better than non-syn and lower viscosity coats the engine faster.

zenofspeed

iTrader: (1)

BTW - Mobil 1 is NOT a full synthetic. neither is Castrol. They cut corners to save money and still "qualify" to advertise as synthetics. amsoil is true 100%
http://theoildrop.server101.com/forums/s...part=1&vc=1

Here is a very good, but long read....
http://www.ferrarichat.com/forum/faq...tor_oil_basics

Although obviously sponsored by royal purple, this is a cool video on how to test film-strength:
http://www.youtube.com/watch?v=kqvhRi7-iMA

Aeka GSR

iTrader: (4)

well it is obvious we all have hit a brick wall and are talking in circles over and over and over. **** it, run what makes you sleep better as someone has already said.