Should i buy an rx8 w/ 80k miles?
03-19-2005, 02:06 AM
#27
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A few things here.
1. Synthetic oils are not bad for a rotary. This is a myth. I don't care who started it. I've used it for years with no problems as have countless others. Racing Beat has recommended Royal Purple for years and before that they used Amsoil. Rotary Performance in Dallas uses synthetics. Mazda uses synthetics in their own race cars. People who know, use synthetics. The only time you don't want to use them is when you are breaking in a new motor since they are too slippery to allow proper breakin of the seals. When at any other time can you possibly have something too slippery?
2. 3000 mile oil change intervals are not necessary. This is really only a common number in North America as the oil companies have most people scared into thinking that their cars will die if they don't change it. Your oil is fine at this mileage. They just want you to buy more oil. Check out Europes oil change intervals. Americans are paranoid. For hard track use, a 3000 mile oil change interval is fine. A rotary is fine at a 7500 mile oil change interval and a piston engine can go 10K+. If you run synthetics such as Amsoil or Royal Purple, you can go 25K on a piston engine with no issues. My Honda has 113,000 miles on it right now, has never had a problem, gets better gas mileage now than the day I bought it, has only had Royal Purple in it, and has only had the oil changed about a dozen times.
3. 80K miles on a naturally aspirated rotary is like 80K miles on a diesel engine. If you treat it right, it will go on seemlessly forever. Rotaries are not unreliable nor do they wear out quickly. Especially not with synthetic oils.
1. Synthetic oils are not bad for a rotary. This is a myth. I don't care who started it. I've used it for years with no problems as have countless others. Racing Beat has recommended Royal Purple for years and before that they used Amsoil. Rotary Performance in Dallas uses synthetics. Mazda uses synthetics in their own race cars. People who know, use synthetics. The only time you don't want to use them is when you are breaking in a new motor since they are too slippery to allow proper breakin of the seals. When at any other time can you possibly have something too slippery?
2. 3000 mile oil change intervals are not necessary. This is really only a common number in North America as the oil companies have most people scared into thinking that their cars will die if they don't change it. Your oil is fine at this mileage. They just want you to buy more oil. Check out Europes oil change intervals. Americans are paranoid. For hard track use, a 3000 mile oil change interval is fine. A rotary is fine at a 7500 mile oil change interval and a piston engine can go 10K+. If you run synthetics such as Amsoil or Royal Purple, you can go 25K on a piston engine with no issues. My Honda has 113,000 miles on it right now, has never had a problem, gets better gas mileage now than the day I bought it, has only had Royal Purple in it, and has only had the oil changed about a dozen times.
3. 80K miles on a naturally aspirated rotary is like 80K miles on a diesel engine. If you treat it right, it will go on seemlessly forever. Rotaries are not unreliable nor do they wear out quickly. Especially not with synthetic oils.
03-19-2005, 01:57 PM
#28
The whole thing with synthetic oils stems way back when (sorry I can not be more specific as I am sitting in Iraq now and the Mazda book I read this info is in Denver) mazda was had first introduced the 7, there was one specific synthetic oil that caused problems with the motor. Mazda could not legally state do not use X synthetic motor oil for some reason, the book didnt go into it, so they put out a blanket statement saying not to use Synthetic at all. The book went on to state that since that time that oil is no longer available since it was causing issues with higher performing piston powered cars as well and they stopped making it. That is where this whole "dont use synthetic oil" supposedly came from. (From what I read and for what it is worth) Actually a friend of my owns a snowmobile shop and we tested several different oils (synthetic and parafin <--- sp? based oils as well as additives on a spinning bearing and and applied pressure to it at a 90deg angle , the rod we applied the pressure with was connected to a torque wrench and the best results we found was Castrol GTX. Even when other oils were mixed with these so called super additives Castrol was the best. After that that is all I will use, not to mentions it is designed for higher heat motors. Not to thread hijack but out of curiosity what oil does everyone else use?
03-19-2005, 02:17 PM
#29
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Originally Posted by rotarygod
A few things here.
2. 3000 mile oil change intervals are not necessary. This is really only a common number in North America as the oil companies have most people scared into thinking that their cars will die if they don't change it. Your oil is fine at this mileage. They just want you to buy more oil. Check out Europes oil change intervals. Americans are paranoid. For hard track use, a 3000 mile oil change interval is fine. A rotary is fine at a 7500 mile oil change interval and a piston engine can go 10K+. If you run synthetics such as Amsoil or Royal Purple, you can go 25K on a piston engine with no issues. My Honda has 113,000 miles on it right now, has never had a problem, gets better gas mileage now than the day I bought it, has only had Royal Purple in it, and has only had the oil changed about a dozen times.
2. 3000 mile oil change intervals are not necessary. This is really only a common number in North America as the oil companies have most people scared into thinking that their cars will die if they don't change it. Your oil is fine at this mileage. They just want you to buy more oil. Check out Europes oil change intervals. Americans are paranoid. For hard track use, a 3000 mile oil change interval is fine. A rotary is fine at a 7500 mile oil change interval and a piston engine can go 10K+. If you run synthetics such as Amsoil or Royal Purple, you can go 25K on a piston engine with no issues. My Honda has 113,000 miles on it right now, has never had a problem, gets better gas mileage now than the day I bought it, has only had Royal Purple in it, and has only had the oil changed about a dozen times.
Good points on the synthetic... many rotorheads I've met also swear by synthetics as well. I plan on switching over soon myself.
Couple questions thought- With an extended oil change interval, do you advocate changing the filter more often? I ran synth in my Miata, and on occasion I would let the oil go 6-7k miles, but I would change the filter out at 3k. Or do you think that modern filters can handle the longer change intervals that synthetics give you?
2nd question- on the RX8 with it's dual oil coolers, unless you tilt it while draining (which I do), you only get 50-60% of the total oil capacity out of it. Don't you think that might be a factor in an extended change interval? Even running synthetic, I personally would not feel comfortable with a 7500mile knowing that half the oil is just diluted dirty oil from the previous batch...
03-19-2005, 02:50 PM
#30
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I always change the oil filter at the same time the oil is changed. It's such a cheap piece to buy, there's no reason not to.
I assume by your response that there are no drain plugs on the RX-8 oil coolers. I don't own an RX-8 so I don't know. On my 1st and 2nd generation RX-7's there have always been drain plugs on the oil coolers. I would drain them at the same time so most of the oil would get out this way. Whatever was left was only a small amount in a couple of lines. It is best to drain as much as you can each time you change the oil. That's really the point of changing it. It's supposed to be an all or nothing affair. If the 8 doesn't have the ability to drain the coolers, I consider this a big design flaw.
I assume by your response that there are no drain plugs on the RX-8 oil coolers. I don't own an RX-8 so I don't know. On my 1st and 2nd generation RX-7's there have always been drain plugs on the oil coolers. I would drain them at the same time so most of the oil would get out this way. Whatever was left was only a small amount in a couple of lines. It is best to drain as much as you can each time you change the oil. That's really the point of changing it. It's supposed to be an all or nothing affair. If the 8 doesn't have the ability to drain the coolers, I consider this a big design flaw.
03-19-2005, 03:31 PM
#31
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Originally Posted by rotarygod
I always change the oil filter at the same time the oil is changed. It's such a cheap piece to buy, there's no reason not to.
Originally Posted by rotarygod
I assume by your response that there are no drain plugs on the RX-8 oil coolers. I don't own an RX-8 so I don't know. On my 1st and 2nd generation RX-7's there have always been drain plugs on the oil coolers. I would drain them at the same time so most of the oil would get out this way. Whatever was left was only a small amount in a couple of lines. It is best to drain as much as you can each time you change the oil. That's really the point of changing it. It's supposed to be an all or nothing affair. If the 8 doesn't have the ability to drain the coolers, I consider this a big design flaw.
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