I never said any such thing, your reading comprehension stinks. I've said repeatedly it's a direct cause and effect, because of mega rich AFRs under boost and gas getting past the seals

 

seamore,

The easiest and cheapest route is to use Castrol GTX 10w-30 and change it every 1500 miles or so. It is inexpensive, you won't have to pay to get it tested and dilution should not be an issue at such a low mileage oil change interval. Blackstone labs doesn't charge much to test oil but you can do an oil change including an oem mazda filter for about what it would cost to get your oil tested. If you want to get into synthetics you will spend more and probably not have the engine long enough to enjoy any benefit. I am a big fan of synthetics, I run royal purple and amsoil in my other vehicles but I don't think it makes sense with this car. If I tracked my car the expense of synthetics would be a minor cost compared all the other costs so maybe it would make more sense. It all depends on what you want to spend and what you are doing with your car.

 

Do you still have this report? I'd be curious to see the measured viscosity.

Another interesting topic: can long term exposure to fuel vapor degrade the coolant seals?

 

Best advice yet but I'd stretch it to 2k or 2500 miles I don't think the fuel dilution is an issue and if anything may help keep those seals and rotors clean.

Stretching the oil changes over 3k is a big no no in these cars because it allows for that dirty oil to be sprayed all over your seals and rotors causing lots of carbon build up which is the reason most of these engines in normal daily driven type cars seem to die.

For all those guys who drive hard; mountain runs, autox, track use etc... I like using a thicker weight oil and my favorite is VR1 20w 50. Synthetics are great but when you change often they're a waste of money. I have found that my car runs cooler with better oil pressure when running on synthetics and I'm sure it's better for cooling and maintaining the turbos but VR1 works well enough (i think it's a synth blend) and I'm comfortable using it. One final note about VR1 is it's a racing oil so it's allowed some leeway in conforming to API standards of zinc and phosphorous (has more) blah blah...in short it'll protect your metal moving parts better than most conventional oils or it's just a marketing ploy that's causing me to waste money lol Seriously though I've always felt that valvoline oils of all kinds come out looking better than most of the other oils I've used through out the years.

 

You said you get no fuel dilution if you stay out of boost.

Since when did I say I "never" go Into boost?

You even reiterated that I said I RARELY get into boost which you actually took literal. Meaning I actually still go wot.

So not only do you need to recheck your own comprehension skills before you tell others to but you also have to stop posting from a closed minded point of view.

Its a one sided battle in which you'll always be the loser.

And your history on this forum proves that time and time again.

 

Interesting theory, but fuel dilution is a disaster for oil properties, so cons likely outweigh pros. Pre-mixing with synthetic and/or water injection and frequent WFO driving is the best approach imo. Driving this car like a granny is a sure means to carbon coated rotor faces.

There was some speculation on vette forums that VR1 is a synthetic blend, but Valvoline doesn't advertise it. Valvoline does produce a specialty racing petroelum oil (non-synthetic) which contains much higher ZDDP (20w-50 is the highest viscosity grade) Amsoil 20w-50 is a great oil and held up fairly well in a recent analysis I ran on it, but still lost a couple of viscosity grades. Synthetic or not, excessive fuel still rapidly degrades any oil.

http://www.tsadvancedsynthetics.com/...nd_Effects.htm
http://www.usoilcheck.com/oilchek/se...l+dilution.asp

 

That's not true! The OMP isn't designed with the pressure to spray any oil. It only dribbles in so the apex seals can squeegee the film across the rotor housing. Mazda has never designed it as a pressure system because coating the rotor face isn't what Mazda was trying to do. It's main purpose is to lubricate the housing and nothing else. The oil condition has nothing to do with carbon build-up. Carbon build-up is a direct result of incomplete combustion on the rotor faces because of the extremely large combustion chamber.

When I rebuilt my S5 NA engine back in 2005 I did an experiment to the rotors. Well the experiment caused very low compression. I had to use ATF to get the engine to fire up. It wouldn't idle at all so I had to adjust the linkage to idle at 2k. After only 30mins of running, the engine still didn't have enough compression to start on it's own. So I broke it back down and couldn't believe how much carbon was already on the rotor faces from the weaker compression. Keep in mind, my OMP didn't work so there was ZERO oil injection. My 20b was been broken down on numerous occasions for my experiments. This engine is 100% premixed and had about 50hrs on it. Every Time I break it down, the carbon build-up is virtually non existent. And that's with the engine idling for 75% of that time. Any carbon present on the rotor face was actually powder based. You could easily wipe it off with your finger. The same couldn't be said for my S5 engine.

So the point I'm trying to make is, the fuel itself turns into carbon when it's not fully burned. When you premix, your constantly spraying an oil film through out the combustion chamber. This film will also lightly coat the rotor faces which reduces the carbons ability to actually adhere to the surface. Eventually the carbon burns away. This replenished film is the reason why you have less carbon build-up on premixed engines.

 

This whole discussion about fuel dilution is moot. Even with a reasonable amount of fuel in your oil, the engine will still blow a seal (apex or coolant) before any oil related damage will cause the engine to fail.

Time for the mods to close another stupid "whats the best oil" thread ........... again!!!

 

This is a rehash of the same worthless argument from mconnor. There are members with 100k+ miles, why assume the worst, why not do everything possible to keep your motor tip top? Oil is cheap, rebuilds aren't. Oil related failures do occur, just ask Bryan at BNR Supercars, and highly degraded oil may be more of a factor than many realize. Watery oil at 8k rpm is not good, I don't care what anyone says to the contrary.

 

You rang?.......

Mebbe I'll let this sucker live a little longer

 

I just ordered a case of this http://www.bradpennracing.com/Produc...ce/SAE-50.aspx

I'll post a UOA in a few months on it.

 

lol this.

Funny how these threads have the same cycle of posts. Usually from the same people. lol

 

What's funny is if you go over to S2KI there are several members who routinely post UOAs and scruntinize every detail of the reports. Almost everyone uses 5w-30 or 10w-30 full synthetic with OCIs that range from 5-10k miles; wear metals are commonly in the single digits and fuel is essentially always zero (n/a), with minor viscosity shear. Then you come here, and if you do see a report, there is consistently very high wear metals and alot of fuel, while many members just throw their hands up and say, "well, f* it, it's going to blow anyway". Downright bizarre.

 

That is because the S2000 is so bloody reliable that owners have bugger all else to talk about.

It is - or the coolant seals will fail - both of which are not related to oil use. And it is relatively cheap to replace the bearings when doing the inevitable rebuild.

FD owners concerned about longevity use auxiliary injection. We amuse ourselves every so often with oil discussions, but do not really take them very seriously.

 

I think oil is a big deal to the rx7 world because i believe people assume oil has a major impact on engine longevity.

So while they have no answer as to when their engine will "go", they try to gather up anything they could thats minor and inexpensive and make a big discussion about it making an engine last longer.

I think the real answer will be the engine builders, not people testing their oils.

The actual engine builders need to post in here and give their input on what they see when they crack open the engine. Because i have been on this forum for a while and im no engine builder but i have yet to see a thread where someones engine blew because of an oil related problem. Meaning from the actual oil.

 

Again, talk to Bryan (BNR Supercars) and ask him about an oil related failure he experienced a few years ago, I think he still posts on rotary car club

 

Nothing more than this needs to be said. Unfortunately, that won't be the case

 

....or maybe effected parties didn't want to post a thread about their engine failure. I know Bryan didn't

 

I am all for making anything last by taking good care of it. I applaud anybody trying to make their car last and there is certainly plenty of satisfaction that comes from treating your stuff well and taking care of it.

It seems like all, or nearly every FD engine failure is related to air/fuel issues or cooling issues. Few would disagree that synthetics are better than conventional. I am sure in a lab test that an FD engine w/synthetic would have less wear than conventional simply because synthetics protect metal better. The FD engine just happens to fail for other reasons before it has a chance to wear out from friction due to inferior oil. Changing your oil often with GTX or something similar can offer great protection. So can running the right synthetic, so can pre-mixing or injecting good 2-smoke oil. Aren't we so lucky to have all these options when all the other suckers don't even get to consider where to mount the oil reservoir or at what point in the pre-mix ratio will the car smoke too much.

 

Maybe someday one of us will convert an FD to CNG or propane. Dilution would no longer be an issue. The oil would certainly stay clean much longer. Put on a dual filter setup. I am sure you could really stretch out the change intervals. I am sure that would be a can of worms and cost an arm & leg. Food for thought.

 

I agree 100%!

 

I don't believe that's really the case. From the two 1st gens I owned, to my 2nd gen (all NA) all of my failures have been carbon related. Carbon is the biggest killer of all NA rotarys (Rx8 included). All these engines had 140k or more and all of these engines had perfectly good/re-usable bearings during tear down. All of these engines had varying oil changes over 3k and different oil brands used. If your engine maintains it's oil pressure and you don't have any major leaks, there is a very high % chance that your engine will NEVER experience an oil related failure. Seriously, rotarys don't commonly die from oil related problems.

 

Per adamc's comment, what's a "reasonable amount of fuel"? 2%? 5%? 10%?

Does the threat of engine failure need to be motivator? How about compression loss? Degraded oil doesn't do its job very well. I find watery, black, stinky oil more than a little disconcerting. I've owned alot of cars, and I've never seen anything like it. The oil in my S2000 looks great after 5k hard miles. In the FD, it looks like hell after 1,000 - and not just my car, every FD I've seen. RX-8s don't have the same level of fuel dilution as FDs do, because they're n/a of course, but thin viscosity and high wear metals (esp iron) also plague RX-8s
http://www.rx8club.com/showthread.php?t=15112

 

To elaborate, specifically what issue related to carbon build-up?

 

Your never going to get the point if you keep comparing the rotary with other piston powered vehicles. Compression lost has more to do with carbon sticking of the seals in rotarys. The factory 3 piece apex seals in the 2nd and 3rd gens are very prone to carbon sticking. The bottom piece will get stuck leaving the top piece to free float with no pressure. This seal will also bounce around and get damaged and will break causing a blown engine. The 1st gens all have thicker 2 piece 3mm apex seals. These seals don't easily break but if you have too much carbon build-up, you can and will experience carbon lock. This is when you have so much carbon that the engine locks up during a start-up as large carbon chunks dislodge from the rotor face and jam the rotor against the rotor housing. One of my 1st gens experienced this exact problem. If the OMP is doing it's job, damage will almost always be due to carbon sticking of the seals and not from the oil on a NA rotary (provided the coolant seals hold up).

On all rotarys, you also have to understand that the load on the 4 bearings is far less than with a piston engine. On a piston engine, the crank bearings absorb all the rotational load. That load is furture increased during the compression stroke. Not so with a rotary because the stationary gears adsorbs a lot of the rotational load. This cuts down on any extra wear the bearings could be getting. Yes the thinned fuel diluted oil will have less lubricative property's, but it isn't enough to cause any major oil related damage. Your really 99% guaranteed to loose your rotary to something other than a oil related problem. OMP failure being the main exception.