Type of Oil for Rotary Engine
11-18-2002, 10:05 PM
#23
Senior Member
Join Date: Mar 2002
Location: Charlotte, NC
Posts: 305
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
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.
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
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.
11-19-2002, 06:02 AM
#25
Super Moderator
Join Date: Feb 2002
Location: Amityville, New York
Posts: 12,288
Originally Posted by 1Revvin7' date='Nov 19 2002, 12:22 AM
thank you dave, u have answered all my questions, but where can i get synthetic 2-stroke premix?
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.
11-19-2002, 08:27 AM
#26
Senior Member
Join Date: Mar 2002
Location: Charlotte, NC
Posts: 305
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.
11-19-2002, 04:26 PM
#29
Super Moderator
Join Date: Feb 2002
Location: Amityville, New York
Posts: 12,288
Originally Posted by Baldy' date='Nov 19 2002, 02:05 PM
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'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?
11-19-2002, 06:17 PM
#30
Senior Member
Join Date: Oct 2001
Posts: 1,370
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.
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.