SilentSpring

No, unfortunately I never had the oil tested. The longest I ever let the oil go was 5k on one occasion and at that point it was so diluted with gasoline that I decided it was probably best to keep it at 3k for the remainder of it's life. Granted this was winter time, and it was during when my commute was about 5 miles so the oil never fully warmed to burn it off.

fevest

How could gas get in the oil?

rotarygod

Extra clamping loads isn't doing anything useful. That is applying pressure in the wrong plane. If using the front of the engine as a reference point, the tension bolts are used to hold the engine together along the Z axis. Studs prevent the engine from moving along the X and Y axes. The bolts only control this to a very small extent.

rotarygod

I have used various oil change intervals but the one I almost never obey is the 3000 mile oil change. It isn't necessary. Especially if you are adding a quart or 2 within that time. The longest I have ever gone on a rotary oil change interval is 10,000 miles. That may be a bit extreme but 5K certainly isn't. I've stated it before but I have never ever had a rotary engine failure and I've had several of them.

9krpmrx8

iTrader: (46)

My fuel tends to have high levels of fuel dilution for some reason and when I was using the Castrol 0W-30 it went from a Viscosity of 12.1 down to 9.1 in only 1500 miles. So where would it have been after 3,000 miles?

Heck when I used to test the Castrol GTX 10W-30, it was usually in the 9.0 range after 3,000 miles and I have seen other 8 owners with a Viscosity of 9.0+ even after 4-5,000 miles on the Castrol GTX and it's not even synthetic. Good stuff.

My Mobil1 is always above 11.00cst after 3,000 miles and if you look at other UOA's you will see 0W-40 is usually above 11.00cst in other RX-8's even after 4,000-5,000 miles.

I have used Castrol GTX, German Castrol 0W-30, Rotella T6 5W-40, and Mobil1 0W-40 and I have tested them all. all I can say is in my RX-8 not all oils are created equally or perform equally. I would got to 5,000 on the Mobil1 in my car but not on the German Castrol 0W-30 so for me personally after seeing the way different oil performs in my car, I don't make blanket statements about synthetic or Dino oil.

bse50

Too bad that using mobil1 oils without a sohn adapter equals to a suicide!

9krpmrx8

iTrader: (46)

Good thing I use a SOHN adapter. But honestly I think that is all BS, I have never seen any proof of it.

paulmasoner

iTrader: (1)

Look outside the rotary community.

Within, there are so many opinions and so much BS. In the world were burning oil isn't a normal debated topic, its much easier to find things to back the claim about Mobil burning poorly

9krpmrx8

iTrader: (46)

I guess I will have to research a bit but I spend a ton of time on BITOG and CC, etc. and I haven't really seen anything.

bse50

Search for rg's oil posts

rotarygod

So your oil viscosity falls from 11 to 9.1 cSt. So what? What number exactly do you consider to be safe vs unsafe and how do you know? Keep in mind that oil loses it's ability to protect below 2 cSt so why do you think 9 is bad but 11 not? What if you started with a thicker oil that had a cSt of 15 at 212*F but it fell to 12? Is that bad?

rotarygod

There's the first problem. BITOG is no different than any other forum. There are about 3 smart people and the rest are mindles lemmings who don't know a thing. There is more bad info there than good. There is some good but figuring out what it is can be tough. If you already knew, you wouldn't need to go there!

9krpmrx8

iTrader: (46)

Well if it fell from 12 to 9 @ 212F in 1500 miles then it could possibly fall to 6 in 3,000 miles and to 4 in 5,000 miles right?

I am familiar with how how forums work and the number of self proclaimed experts so I take most of what I read online with a grain of salt. I am no scientist so I just read and try to understand what I can. If you ask three different "experts" you are likely to get three different answers. I work with a lot of Lawyers and Doctors so I have found this to be true in most professions unfortunately.

PhillipM

Bolts control movement through friction between the bolted surfaces, except in a very small percentage of applications where they are directly placed in shear (such as aircraft composites where they can't risk fibre damage, usually with a press/tap fit into the hole to take the loadings). So they do have a large effect on X & Y axis twists - you're looking at about 18% more clamp load or so (depending on the exact strength of the housings, I've had to guess)
However, if the clamp load is becoming high enough that it starts distorting the housings around the bolt holes, then it's doing nothing, could even warp the plates.
Like I say, it was a big *if* :D

rotarygod

You hit the big problem. The aluminum housings start to compress. Even if there were 18% more clamping force, that's hardly anything compared to what dowel pinning does in the correct direction. This is not an acceptable option to dowel pinning. It's not even close to equal. A bolt is also not an acceptable substitution to a stud where strength is concerned.

Brettus

iTrader: (2)

/\ you have to be very careful when dowell pinning the renesis as the front dowell hole doubles as an oil gallery and the casting around it is very weak .
ask me how i know

PhillipM

A bolt the same size as the stud would be just as strong if specced correctly, after all, the loading should be through the shank anyway in case of movement.
What's more, the stud will have to have some amount of clearance/movement to allow assembly, and that will grow when the housings get hot if you have a steel stud, whereas the clamp load from a bolt effectively gives zero clearance, and the clamping load increases when the engine gets hot to boot. Studs aren't particularly a higher strength solution, depends on the application, but they're usually used more for much more precise location, they do take a lot of shear load but if you consider the clearance problem then you have a good chance that only one dowel is actually taking the majority of the loading (as unless it or the housing compresses sufficently, the clearance reduces the load taken by the other dowels, although the hollow, split expansion-type bushings help there, by taking a little of the clearance up by acting as a spring). Which means the housing has to have already moved for them to be 100% effective.

However, I can't help but feel that if Mazda thought the housing threads - and the aluminium housing around the bolts - were both strong and rigid enough to take the extra clamping load from an M12 bolt reliably, without distortion then they probably would have done it to start with, given the cost to them would have been miniscule....
Not only do you have more load there, you've got it on less area than a stock engine as you've drilled the housings too....in which case you're only real choice without making new housings is dowels.

rotarygod

No a bolt isn't as good as a stud. It all comes down to how the tightening torque is applied and not how strong the bolt or stud itself is. With a bolt, all of your tension is being applied at the threads only and not at the head. With a stud all of your tightening tension is being evenly distributed at each end. This takes less stress off of where it threads into the housing. It also allows a more uniform a consistent tightening torque to be applied.

You only want a bolt or stud to clamp the engine together front to back. That is all they should do. The dowel pins are used to strengthen the engine from trying to twist apart and obviously do nothing to hold the engine together front to rear. You don't want one thing doing more than one job. A big problem with rotary dowels is that they only go halfway through the engine rather than all the way through. This allows for more locations for stress to be put on the housings with any flex. A longer stud going all the way through would help this even without adding anymore. This alone would do far more than just using better bolts would. Adding a couple would be even better. Tension bolts should have never been used in this engine. They should have only used studs. Many people use larger studs of bolts to try to do the job of dowel pins but this is inferior and ultimately futile as it may do something but it can't do much. The studs help over the bolts but by their very nature are better than a bolt anyways. A larger bolt kit is a complete waste of time.

PhillipM

I've probably read that wrong, or I'm getting mixed up with what you're trying to say, but tension is applied on the whole length of the fastener, not just at the threads. Otherwise it couldn't, by definition, be a tensile force, no?
It's like pulling on a rope, whatever force you put on one end has to be present at the other...