This stuff:

http://www.amsoil.com/products/tro.html

 

I've really been debating on switching to synthetic, but haven't tried it yet. I can imagine the reduced wear/temperature would be great on our cars.

 

I've been thinking of switching....I started a thread of the same topic not long ago and hardly anyone responded

I'm running Mobil 1 15w-50 right now and I doubt this stuff is that much better when you change your oil every 2k, but who knows....I'd like to see how the temps compare between Mobil 1 and Amsoil under high load conditions....20w-50 is a a pretty heavy oil for street use, the oil pressure will be high, esp when the engine is cold....heavy oils resist viscosity loss and oil/gas dilution better though, especially if you are on the boost all the time

I'm completely sold on the Amsoil 2000 2 stroke oil, in fact I started pre-mixing it in the FD

 

Just to stir the pot a little...

Has anyone ever heard of a rotary engine part being outside of spec due to plain old wear? I have never heard of any oiling issues in a rotary and come rebuild time the parts that are typically unusable are either warped from over heating or deeply gouged from cracked apex seals, etc.

Maybe the rotor bearings would last longer, but over the life of the motor having to replace rotor bearings during a rebuild is far cheaper than paying for synthetic oil at each oil change for the life of the motor.

I absolutely agree that synthetic is a better product, but history seems to prove the rotary is going to fail in some catastrophic fashion that has nothing to do with oil, and conventional oil is damn good stuff.

What advantages in the long run for the rotary does synthetic have other than lower oil temps?

Let's assume a motor doesn't blow up and lasts 100,000 miles and that you changed the oil every 3000 miles. That is 33 oil changes. Let's say each oil change uses 5 quarts because you put 4 in the motor but then add the fifth before the next oil change due to OMP consumption. That's 165 quarts of oil for the life of the motor. Let's say synthetic costs $5 a quart and conventional costs $2. That's a difference of $495 over 100K miles. If you change your oil every 2000 miles the difference is $750! Is synthetic oil going to save you $500-750 in parts when it's time to rebuild? I don't see how it would.

Again, I don't debate synthetic being better stuff and if I wasn't paying for it I would use it without question. But I cannot make synthetic make sense economically unless I am missing something.

 

Hi, even though I don't have a rotory I thought I would tell you my experiance with synthetic oil. I have been using synthetic oils since I bought my Z new in 1992. And yes for the first 6000 mile I used regular oil (Break in period). Now I have a little over 120,000 miles on my engine and turbos and have not had to open my engine up at all. I recently had a leak down test performed at XS Engineering and I had 160 compression from cylinder 1-5 and 150 on #6 cylinder. Eric Hsu was very surprised at my #'s considering that my Z is modified and the amount of miles on her. When the Z engine is new it has a compression on 190-185.

My friend who use to have a 94 RX-7 swore by synthetic oils and the reason why I used it. I have used Amsoil oils on my Z since I switch from conventional oil. I know our engines are different but I thought I would share my experiance with you guys.

 

Less friction=more power.

And synthetic is most definitely better for those little snails hitching a ride on the passenger side of the motor

 

ewwwwww. Good point.

 

I was running it until I wrecked. I will be running it again. Pricey though. I invested in cases of it so I have little choice anyways

 

DamonB,

I may have a way to, at the very least, break even in terms of cost. Has anyone considered:
http://www.oilguard.com/side_menu/by...pass_intro.php

I bough one, see my engine rebuild thread ... https://www.rx7club.com/forum/showth...readid=152636.

I'm still in the break in period and running dino oil. When I hit 3000 miles, I intend to switch to Mobile 1. I'm thinking 10w30, but I haven't decided on the exact weight yet. My intention is to have an oil analysis done at 3000, 6000 and possibly 9000 miles. If the filter works as promised, I should at least be able to break even in the synthetic vs dino oil thing ... including the cost of filters and the bypass kit. Note that the last item will have to be spread over the life of the car. My only concern it gas dilution. I won't really know how much of an issue this is going to be until I do some oil analysis so see what's going on. See this thread for more info:
https://www.rx7club.com/forum/showth...ight=dilution.

Call me obsessive, but it would make me feel better knowing that there was synthetic pumping through the turbos just before I turn off the key.

James

 

James, the dilution issue is why I always see synthetic costing $$$. In a piston motor the real savings with synthetic is more mileage between oil changes. Alas, with the rotary and it's gas diluting the oil no matter what you put in it's going to be dilluted by gasoline. That's why even if I used synthetic I would still change it at 3000 miles. On a piston car I would not do that; it wouldn't be needed.

 

oil dilution in these engines is somewhat inevitable because of the poor separation between intake and exhaust, inherent with the rotary design....two strokes suffer the same problem

even with my new rebuild, the oil still smells like gas all the time and gets black REAL QUICK, which is a good reason to run 20w-50 I suppose, dino or synth, and change it more frequently....these fancy "bypass" filters can't remove gas from the oil, either

I'm sure you guys have already seen this http://www.scuderiaciriani.com/rx7/oil.html near the bottom of the page "gas smell in oil"

 

Hmmm. I rebuilt my own motor, and the oil stays relatively clean and doesn't smell like gas at all. This is running 17 psi routinely. It's all in the clearancing of all the seals.

My old motor was the exact opposite---oil constantly smelled like gas and diluted. Imagine my surprise when I found that the side seals were all loose, the rotor bearings were badly chewed up, and my eccentric shaft was so scored up that it was almost unusable. I guess it was fortunate that I cracked a seal and had to rebuild. Be careful who you let work on your 7s, boys......

 

What you have to consider is what happens to the oil when it is either pumped into a very hot turbo or worse yet injected into a combustion chamber. Some oils will burn off fairly clean some may turn into gook. Get a torch and a pan and try it.

 

It felt like enough of a challenge to pull, strip, build up and install the motor this time ... next time, I intend to do the rebuild myself. The rest should be second nature by then ...

I may even buy a 1st gen, with a shot motor, to rebuild and sell. When I rebuild my FD I should be able to do a GoodfellaFD3S sort of job.

 

Hmmm. I rebuilt my own motor, and the oil stays relatively clean and doesn't smell like gas at all. This is running 17 psi routinely. It's all in the clearancing of all the seals.

My old motor was the exact opposite---oil constantly smelled like gas and diluted. Imagine my surprise when I found that the side seals were all loose, the rotor bearings were badly chewed up, and my eccentric shaft was so scored up that it was almost unusable. I guess it was fortunate that I cracked a seal and had to rebuild. Be careful who you let work on your 7s, boys......

I haven't done a compression check yet but I think my engine is pretty tight...it's a mazda reman from malloy and mr. rx7tt (chris rogers) checked it out when he did the street port/coolant seals and said everything looked great....I wouldn't say the gas smell is overwhelming (definitely less than before with my old engine) but it certainly is noticeable

I'd be interested to see analysis of your oil after 2-3k miles, Rich, to see what the oil dilution actually is in hard numbers....how many miles to you have on your engine and is the oil still free of gas smell after 2-3k miles?

anyway, I'm sure tolerances have alot to do with it, but again I believe that some fuel dilution is almost unavoidable in a rotary unless you rebuild the engine every 5k miles

it's another reason to upgrade to JimLab's solution, ha....kidding

 

Synthetic is better for the turbos which can cost more than the motor BTW I've been running Royal Purple 10w-30 for some time now...

 

So who makes the best oil? Amsoil, Mobil 1, Royal Purple, Redline? Who?

 

I use Mobil 1 15-50 in the oil pan, and ams-oil 2 stroke synth racing formula in the gas tank!

 

Garfinkle has used Amsoil for several years ( 24 or 25 now ) . Motor oil in the pan ,2 cycle oil to the oil metering pump . Amsoil grease, ect,ect. It is in his motorcycles also .One of his friends ,customers is a dealer so he gets it at cost . My 7 has it in the trans and rear end .