I have had my '87 RX-7 for 8 years and have always used Castrol Syntec (Full Synthetic) 5W-50. Today I have been told by the dealer that they no longer recommend using full synthetic for rotary engines. Does anyone have any input, comments, etc. regarding this issue. The dealer said that carbon will build up in the engine and the engine will lock up. I have always known that the full synthetic will build up in the engine, but I have also heard that if you run the engine a little harder than normal (about 4000 rpm between gears about once a month), the build up will burn out. I have never had a problem and would just like to query everyone regarding this issue. This morning, I actually had to sign a waiver at the dealer to let them use the full synthetic in my RX-7 (first time that the dealer has ever made me sign a waiver and informed me of this issue). Any advice would be great and if you do not mind, could you email me at jsc1976@prodigy.net



Thanks in Advance, I look forward to the many discussions on this site.

Well... you're really not suppose to be using full synethetic on our cars - it's not good (that i've been told). You're suppose to be using Non-Syn....



I do know that the carbon build up in our cars is gonna be normal whether or not you're using Non-syn. or Syn. oil. That's why it is suggested to redline her every now and then to flush out the carbon build up.



I know it's probably not much help - but if I'm wrong.. anyone, please correct me.

there is going to be carbon build up either way, the difference is not as great as the diff between running your omp and running 2 stroke in your gas. GLHS has over 300,000 on his rotary and he is running 2 stroke.



Justin

Justin -



"billy" off the other forum and I were talking about that last night with a few other RX-7 guys. He mentioned that if you go 2-stroke... it doesn't feed oil... ah, and something else. I thought it was pretty interesting.

Go to www.FC3s-PRO.com read ted's writeup on pre-mix. I personaly ditch the OMP system completely. I run Royal-Purple Synthetic in the Crankcase and use Bombadier Synthetic 2 Stroke for my premix.

I also don't recomend synthetic, I blew an engine once, alot of carbon builded up because of the OMP. It doesn't burn well. If you do disable the OMP you can use synthetic with good results. You will get some oil sipping between the housing over time with synthetic. Synthetic tends not to wet the oil seals and o rings like regular oil does.



C

like everyone else said! If you're still using your OMP, don't use synthetic. I've always used Castrol GTX 20W50. If you don't know what an OMP is, it's an external oil pump on the front of your engine next to the main pulley below the water pump and alternator. It has clear tubes running from it up to the intake manifold.



Welcome to the forum...

I'm disabling the OMP on my new motor, I've been thinking about running synthetic in the engine as a result, but I've read mixed opinions on doing so still... apparently you will have more oil leaking past the oil control rings into the combustion chamber if you run synthetic.



How many miles do you have on one of these motors you have been running synthetic on? Any smoke at startup ever? I'm very curious... motors almost ready to go in the car, hopefully I have a good solution when it comes time to fill up the sump https://www.nopistons.com/forums/pub...IR#>/smile.png

Just run normal oil and change it every 2-3K miles and you shouldnt have ANY problems.

i plan on running premix for my new motor, i just ordered the block off plates for it

cool, do you plan on using synthetic in the engine sump then?

i don't know yet im about to go ask the homies.

????? what https://www.nopistons.com/forums/pub...IR#>/dunno.gif https://www.nopistons.com/forums/pub...IR#>/dunno.gif



i generally dont like to feed my oil, rather i like to put it in my gas or in my crankcase......



if you are reffering to the fact that it doesnt inject it, it does, just does so through the fuel injectors rather than the oil injectors



Justin

my buddy ran synthetic in his bp and we opened it up a year later and it was clean as a whistle. they reason y we opened it up was casue he wanted to port it bigger

oh really, ur the 1st person i have heard that has gotten to open up a engine ran on sythetic. hmm.... u should post that in the big thread in the third gen section.

I use Castrol 20W-50.... one its burns clean and i've never had any problems. With synth its a good idea if your racing the engine because of the vast temperatures that you put on your engine. The synth hold thier vescoity a lot better. But racing engine only need to last one race and any build up cause by the chemical doesn't matter. For the average rotary engine though build up is a fact of life. Carbon can be burned off with regular care and ATF autotrany fluid but syth chemcail build up may not be the same story. I've never seem an egine that was in a need of a rebuild becuase of synth oil use. But I know 100% that if you use 20W-50 all you have to worry about is the Carbon.

????? what https://www.nopistons.com/forums/pub...IR#>/dunno.gif https://www.nopistons.com/forums/pub...IR#>/dunno.gif



i generally dont like to feed my oil, rather i like to put it in my gas or in my crankcase......



if you are reffering to the fact that it doesnt inject it, it does, just does so through the fuel injectors rather than the oil injectors



Justin[/quote]

LMAO at Muad!

OK...I'm getting castrol high-mileage 20w50 for my first oil change that i'm gonna do on this car...how many quarts will I need?

You'll need to 4 to 5, just check the dipstick after 4.

i am a person who uses different oil also. So many people have said not to use 10W-40 but ive used it for about 40,000 miles and havent ever had a problem..and its not hurting the motor at all. I just recently had a compression test done and i hit 90 all the way acroos the board...no dips ....so is using 10W-40 all that bad because 20W-50 seems a little think to be runnung ..wouldnt burn as good i wouldnt think...Can anyone tell me why they say its better to run that?

i would say change the oil at the intervals recommended by the manufacture and whats listed in the owners manual as to what grade of oil to be used ive used castro 10-30w and have never had any problems with my rx.

This is also a hot topic in the 3rd gen section.

Synthetic motor oils resist fuel and high temperature break down far better than conventional oil. Carbon buildup is a problem in rotaries running conventional oils, just go to any junk yard or engine builder and look at stock motors run on Pennzoil, or such. The buildup of carbon contributes to abrasive wear but also acts as a heat sink to cause hot spots which promote further oil buildup and eventually engine problems.



As for the people that say "synthetic oil doesn't burn as well" that isn't all that acurate. The combustion temp of a rotary engine is between 1200F and 1600F. With that in mind most synthetic oils burn at approx 400F to 600F. So if the oil is burned at say 600F and the temp of the combustion cycle is at least 1200F, how can anyone say it doesn't burn? The old wives tale of it not burning as cleanly is no longer acurate either. Synthetic oils that were being made when the RX-7's came out were far less advanced than they are today. Porsche engines can run 15,000 on Mobil1. Being as that is the only car out there that I would "upgrade" to over my FC's, I take their word for it. Would they recommend something that would make them have to replace a Porsche engine? Nope.



Now for the 20W50 vs 10W30 debate that will surely surface https://www.nopistons.com/forums/pub...#>/biggrin.png I see it like this:



If 2 people are running down the beach, and one is knee deep in the ocean and the other is running in just wet sand, who has the easier run? Obviously the person running out of the water. The same applies to your engine. If you run 20W50 in your car, it had better be 100F+ durring most of the time you drive or you are not protecting your engine as well as you could be. Sure you have more pressure since it has to push thicker oil through the system so it shows higher il pressure, but what you want is oil flow, regardless of pressure. You are flowing less oil through the oil system with 20W50 than you would with 10W30. That is why the pressure goes up because it can't push it through as fast as the thinner oil.



I have run 10W30 in my cars since I have been into rotaries. I only went to 20W50 when I converted the Project 86 from N/A to a TII to bump up oil pressure. When I modified the OPR I changed back to 10W30.



Mazda Competition (Mazdaspeed) recommends synthetic motor oils in there Competition Manual. The Mazda 787B in the 91 LeMans' race ran on synthetic motor oil. Are they wrong?



We recommend using synthetic oils in your entire drivetrain including your engine. I run Mobil1 in my cars, with and without the OMP. I just mix less for the ones that use the OMP. I just tore down my 88 GTU engine that had been run on premix for the past 4 years, and there was barely any carbon buildup. It ran synthetic 2-stroke oil (premixed) and Royal Purple street version 10W30 prior.



People will use what they think is best, but this is just my thoughts on it and what I have learned from talking with lots of people about it.

thank you dave, u have answered all my questions, but where can i get synthetic 2-stroke premix?

Amsoil makes a nice 100:1 synthetic pre-mix.



Burns super clean, a really god jet ski tuner here turned me on to it, stuff is nice!

Ive mentioned before how come no one uses the Amsoil sythetic pre-mix, maybe becuase people would rather buy the cheaper/easier to get stuff.



Just get a case of the **** and you'll have more then enough for a long time.

Yep either Amsoil or Royal Purple 2-Cycle TCW III are both great. Just do a search online and you should be able to locate them quite easily. I know Racing Beat sells all of the Royal Purple products.

vosko told me to run 10w50

Let's beat the dead horse...



I'm about to put 20s50 in mine, non synthetic castrol for high mileage cars...I know it may not be the oil of choice, but is it all that bad?

I think that high mileage oil is bullshit personally, for an older engine I would just put the 10-40 in it.

i didnt bother reading every1's posts...lol



in my 7 i always ran the Cheapest ****. Straight up Discount auto oil. Never had ANY problems with the engine. Every mechanic i took it to said that my engine was in badass condition... It did run hard as ****.



i would personally stay away from synthetic... premix is pimp, but its a hassle for a daily driver.

Most mechanics that arent too experienced with rotaries are impressed with how well a high mileage running rx-7 runs... they are just such smooth engines it can be surprising to those not familiar with it. When I used to visit the muffler shop I worked at a long ass time ago in my 7 to do an oil change or get tires put on it the mechanics wouldnt believe it was a 100k mostly stock NA car.... especially when I left two equal length long ass patches accross the lot (they didnt know it had LSD either)... I tried my best to educate them on the mysteries which rested under the hood but strangely most of them preferred to stay ignorant, mechanics are weird... I guess they didnt like the lack of a valvetrain.

What Exactly are the advantages to running no Oil Metering Pump (OMP) & premix vs. having one and using the engine as it was originally designed?...also how exacyly do you premix?

omp = easy for everday normal ppl, if it breaks(which is somewhat hard to tell, unless u have an s5) and u don't notice ur focked



premix=

1) don't have to worry about not getting oil to the apex seals

2)cleaner engine (burns cleanly and completly) no carbon buildup!!!

3) u can run synthetic in the crankcase w/o worry about does it burn completly since it won't be burned

4) smoother running

5) inconvient for average mofo.



to premix u just through in some 2 stoke oil before everyfill 1oz per gallon if not running the OMP

i use Valvoline VR-1 20/50 in my FC. it has worked fine so far and they recommend it if you

run your car hard

1 oz per gallon..whats that in ml per liter? European member.



John

Oh,one more thing, when running the omp plus premix, what is the recommended ratio...in ml per liter.

Many thanks



John

so, every time i am poor and need just $5 gas..i have to add premix?...this is where i am totally lost

Yes you would have to do stick to the gas : oil ratio you use at all other times.