Kento

Uh huh...and how long are they running those engines for before tearing them down for maintenance, as well as replacing the oil?

Again, this is what I meant by what type of engine and how long. I'm not saying that using 0W20 or other thin viscosity oils is dangerous. But doing it without the proper analysis of application beforehand is taking a risk, especially for street-driven cars.

2ZZ-GE

so, Kent ("mr. oil knowledge"...the articles in Sport Rider were a great read btw) what are you running in your FD right now?

I'll stick with my Mobil 1 15w-50 for the time being, thank you very much....it flows very well cold, contrary to the rhetoric on here, and I'll take the added protection against extreme abuse a turbocharged rotary dishes out, plus 10% fuel dilution, which is unheard of in piston engines

I personally believe these engines are harder (dirtier, more blowby, more heat) on oil than any other four cycle IC engine, that includes a YZF-R6 revving to 15k frequently

the lack of oil related failures in these engines is more a function of the beautifully simple design of the engine than anything else, although the apex seals wear fairly quickly

edmcguirk

I agree. They were not trusting the engine to the thin oil for race distance. What they did say is that they did not see any dramatic changes in the engine wear after qualifying with thin oil.

I also agree that using a thin oil without comprehensive testing is taking a risk but I also believe that using an oil thicker than the spec for the engine is also a risk that people don't seem to notice.

It looks to me that modern synthetic oil is good enough to protect the engine at standard spec and probably at thinner than spec as well.

I see significant advantages to running thinner oil but I also see significant risks. I bring the idea up here in order to get facts from people more knowledgeable than me before I take the risk with my own engine.

ed

(unfortunately my situation has suddenly changed enough so that I might not race this year)

Kento

Motul 300V4T 10W-40, but I feel that any good Group IV PAO or V ester-based synthetic brand is fine...including Mobil 1.
The problem there is that those engines don't exactly run for a whole lot of miles on that thin viscosity oil, which is what I was getting at: If you don't know for sure that a 0W oil is safe for extended use (as in 1500 miles plus), you're taking a major risk with viscosity degradation.
Agreed, but the risks of running a thinner viscosity oil from spec far outweigh the risks of running a thicker viscosity oil that is only one to two steps in multi-vis grade than spec. Running a 15W-50 oil isn't like pouring in straight 50W; a half-step in grade (or even a full step, like running 20W-50 oil) isn't going to kill your engine. However, the risk of viscosity degradation in a 0W multi-vis oil over an extended period is something I have big reservations about.

edmcguirk

Just to clarify, the oil in the qualifying engine was not a 0W (winter) oil it was a 0 weight oil. Well below a 20 weight oil.

tmiked

15w-50 M1 has always seemed to be the prefect RX-7 oil to me.

One thing not mentioned so far is that 'dino' oils tend to thicken over time at temperature because they are mixtures of hydrocarbons and the lighter fractions boil off first.

Kento

All semantics and technical references aside, that's what I meant by my "W" abbreviation when used singularly .

Julian

iTrader: (14)

Yeah they thicken form the paraffin (wax) left behind

a3dcadman

iTrader: (1)

As I mentioned earlier in this thread, I am on my second batch of 0w30 Mobil 1 extended performance oil. I always inspect my oil when changing it and I always change it when the oil is still hot. Prior to trying the 0w30, I used exclusively mobil 1 ext perf 15w50. My car and engine are relatively new with the mileage just passing 40,000 of which I put 21,000 of that on in the last 18 months. After putting 3000 miles on the oils, I could not detect any discernable differences in the color, the smell, the feel, the presence of particulate matter, or the viscoscity of the 0w30 as compared to the 15w50 at the time of the oil change. I will monitor this second batch and see if there are any contraindications for using this new blend that I can detect.
chuck

Kento

Um, no offense, but you can't analyze an oil by smell, feel, color change, or the presence of particulate matter (I'd hope that your filter would take care of that). And the only way you can discern viscosity change is through lab tests; you can't just look at it draining out of the oil pan and say, "yeah, it looks the same."

edmcguirk

I checked in with my friend who works in the pit crew for a Star Mazda team. He says they gained 10HP through oil changes in the tranny and engine but they run the very thin 0 weight oil in the engine and only get around three races out of an engine now. (although there were some other changes besides oil that may contribute to this)

$6K a pop, ouch!

After talking with him over that and a few other items, I realize that thin oil has no place in amature racing. The difference in hot viscosity is really not that big for pumping losses and the heat transportation of faster flowing thin oil is also not that big. The real benefit in thin oil is during the warmup phase. I will probably stick with 0W20 oil on my street cars but not my racecar.

ed

Kento

Just to clarify :
Maybe not in that particular rotary engine, but in other engines it can make a difference. Pumping losses at the oil pump are really dependent on the length and number of oil passages, the various clearances, and what pressure the relief valve is set at.

a3dcadman

iTrader: (1)

Kento,
Judging from the posts of yours that I have read, it is apparent that you possess more gray matter between your ears than most and I certainly appreciate that quality in individuals.

Realize that my statement was of a subjective nature and the basis for my opinion / educated guess. Im an old fart and have been playing with hot rods and sports cars since the late sixties (you know, when the dinosaurs roamed the earth and probably before you were born). I dont profess to knowing it all, but I can tell you that I have gained a wealth of knowledge and experience over the years to qualify, substantiate, and possibly add a bit of credence to my statements of opinion and certainly my statements of fact.

You are absolutely right regarding the efficacy of a lab test for a definitive analysis of the oil. Obviously, laying under the car watching the oil drain doesnt provide conclusive data on the condition of the oil. Since I have the oil from the last several changes, I can at my leisure inspect it, compare it, smell it, feel it and get a sense of what is happening to it. In addition, I can compare it to new oil to establish a starting point for comparison. Notice I said "sense" .

If I was tracking my car and subjecting it to the rigors of racing, I would most certainly scrutinize all aspects of that slippery liquid at a much higher level consistent with its use and application before indiscriminately dumping it into my engine.

I realize many on the forum dont understand that you cannot believe everything you read. Separating fact from fictiion and bullshit from credible well thought out opinions eludes many as well. So for those naive and less informed individuals, thanks for the disclaimer - point taken.

chuck

Kento

Apologies if my post was somewhat abrasive.

My whole point in this thread is this: Ultra-low viscosity oils can provide minor performance gains and still protect an engine in high-stress applications. The problem is that the rotary is different than other engines, especially in the demands it puts on the oil. I've seen lab results showing a marked viscosity degradation of 5W-30 and 0W-30 multi-vis oils in "shear" tests, where two surfaces grind against another under high pressure. The only time most motor oils see this in conventional engines is at the cam lobes/lifters. Meanwhile, the rotary is not only depending on the oil for a good part of its cooling capability, its stationary/rotor internal gears subject the oil to a constant shearing effect, which can degrade an oil's viscosity much quicker.

Based on that, I wouldn't be comfortable running ultra-low viscosity oils in a rotary for an extended period of time. Just not worth the risk IMO.

a3dcadman

iTrader: (1)

Im not so sensitive that an apology is necessary, but thanks anyway. Just wanted to clarify my statements. What would be considered an extended period of time. I dont consider 2000 - 3000 miles an extended period of time for a vehicle that is not being used as a race car whether it is a rotary or not.

Any articles I have read discussing engine oils were generic but still informative. I would be interested in checking out any data regarding the degradation of oil due to this shearing effect or any studies on the effects a rotary engine or turbo rotary have on engine oil. So if you know of any links pertaining to this info, technical or otherwise and used in racing or daily driver applications, send them my way.

There has been a move to 0w and 5w based oils in many of the high performance cars currently in production. I believe that most if not all are piston engines with the exception of one. This leads me to believe that there have been improvements in the synthetic oil formulations currently available. Technological improvements in engine design may attribute to this migration to this new genre of multi vis oils as well.

chuck

Kento

It's quite possible that 2000-3000 miles might be within the limits of safe viscosity life for a 0W-30 oil. Problem is, nobody is sure whether it is or not.
Sorry, don't know of any links to the info you seek. The shear tests were part of a magazine story that I was involved with.
That's my point. You're dealing with an engine that was created with materials and technology from the early 90s (with R&D probably done in the late '80s), not a new generation piston engine from 2005...

The real reason for the move to ultra-light viscosity oils is fuel economy, not performance.

Trevor

I run 5w30 even in the heat of summer. Two reasons:
- I have dual 34 row oil coolers. High oil temps are not a problem.
- Mazda reccomends it. Come on...who here can really say they know more about the rotary than them...

A question for you guys though...I understand fuel dilution is a problem with the stock tune. How about after you've retuned the car to idle and cruise at 14.7:1 and leaner on a wideband? Anyone have any concrete numbers? The reason I ask is because I tuned to that and the fuel in the oil smell isn't near as extreme as it once was.

edmcguirk

I recently read a good article promoting thinner oils but I can't find or search the link anywhere. It was written by a guy studying what oil to put in his street driven Ferrari. It convinced me to run 0W20 oil in my street driven piston engines. If anyone knows the link please let me know.

While searching for that article I came across this article which was one of the better articles that helped persuade me not to run thin oil in my racecar. Although it has a few tiny mistakes, it seems well researched and leads me to think that 5W40 Mobile 1 Truck & SUV oil might be the better oil for a racing rotary engine. (look for the CI-4 API rating)

http://motorcycleinfo.calsci.com/Oils1.html

I had heard about non-synthetic oils labeled as synthetic but this is the first place I read a decent explanation.

ed

Kento

That's because there's far more information out there than just the searching the internet. And it's a lot tougher to publish BS than it is post a page on the internet.

edmcguirk

I finally found that web page I was talking about.

Who really knows if this guy knows what he's talking about but his information does line up with other information I have read in other sources.

It convinced me that all my street piston engines will get 0W20 oil if they can maintain good oil pressure with it.

http://members.rennlist.com/oil/Motor%20Oil%20101.htm

I don't think I will experiment with my own racing rotary anymore but maybe after someone else tries it out.

ed