Lets look at expo1's over 100K renesis motor
03-10-2008, 08:31 PM
#277
.Let me know if I can serve and if I have failed to do so properly at any time. I look forward to hearing from you.
Paul.
We can start a thread about it
03-11-2008, 08:00 PM
#279
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03-11-2008, 08:16 PM
#280
Surf Hard, Drive Hard
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If you haven't seen it yet guys...check out this guys thread and story! 
https://www.rx8club.com/showthread.p...43084#poststop
We need to get Mazmart to tear down this one!
Dave
https://www.rx8club.com/showthread.p...43084#poststop
We need to get Mazmart to tear down this one!
Dave
03-12-2008, 06:17 PM
#282
03-12-2008, 11:50 PM
#286
Administrator
iTrader: (7)
+1 for video
04-01-2008, 08:45 PM
#288
Registered User
Hello people. I'm new here and new to the rotary engine. I must say this was a very imformative thread. While there is some disagreement about the cause of the bearing wear, as was expected, I do think the fact that Mazda recommends heavier oils in other countries speaks volumes. So minimally, I'm caught between 10w40 castrol gtx (lowest flashpoint) and 0w40 Mobil 1. Isn't there a 0w40 Castrol Syntex from Europe that's intersting (the green stuff)? If so, I'll look into that one as well.
Thanks for all the good information.
Thanks for all the good information.
04-01-2008, 09:30 PM
#289
just go with the castrol it will be fine---fi guys should be running 20w 50. most bearing wear is being caused by the dry start up anyway. usually on the front eccentric bearing. At 50K mine was to the and into the copper in the usual spot. I was using 10w 30 and 10w 40 the entire time. I had more carbon than i have ever seen.
olddragger
olddragger
04-01-2008, 09:34 PM
#290
One Shot One Kill
10w30 with more carbon thatn u have ever seen?... tats wat i run.. and i premix o.O.. though i spank my car pretty damn hard everyday.. think tats good enough or should i start doing carbon cleaner on every 4th fillups?
run Vpower and techrons only.
run Vpower and techrons only.
04-01-2008, 09:49 PM
#291
Through a gas additive will not do it. Do it the shop way and the longer it soaks the better. The smoke is just smoke---for show.
Thats not a real sniper pic you have there and why do you have the Marine corps saying on your avatar? Are you connected?
OD
Thats not a real sniper pic you have there and why do you have the Marine corps saying on your avatar? Are you connected?
OD
04-01-2008, 09:50 PM
#292
Registered User
I'll probably do just that (Castrol GTX 10w40). One intersting point I might mention. It does seem that the last reason left (no longer is there a seal compatibilty issue with synthetics, best I can tell) to stay away from true synthetics is the higher flash points. FWIW, the high mileage Mobil1 10w-30 has a flash point equal to Castrol GTX (392 degrees Fahrenheit). The normal Mobil1 flash point is 447 degrees Fahrenheit. So perhaps, if there is one last reason not to use the synthethic, it appears the mobil1 high mileage oils have a flash point consistent with the lower flashpoint conventional oil, like Castrol GTX. For comparison, the flash point of conventional Penzoil is about 420F (using the same closed cup method I think). For further comparison, a typical 2-cycle oil has a flash point of about 160F. I think gasoline is about -40F.
04-01-2008, 10:48 PM
#293
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It does seem that the last reason left (no longer is there a seal compatibilty issue with synthetics, best I can tell) to stay away from true synthetics is the higher flash points. FWIW, the high mileage Mobil1 10w-30 has a flash point equal to Castrol GTX (392 degrees Fahrenheit). The normal Mobil1 flash point is 447 degrees Fahrenheit. So perhaps, if there is one last reason not to use the synthethic, it appears the mobil1 high mileage oils have a flash point consistent with the lower flashpoint conventional oil, like Castrol GTX. For comparison, the flash point of conventional Penzoil is about 420F (using the same closed cup method I think). For further comparison, a typical 2-cycle oil has a flash point of about 160F. I think gasoline is about -40F.
04-01-2008, 11:34 PM
#294
Purveyor of fine bass
I switched to Redline 10W40 and my gas mileage went down the drain (down to 14.5-15 from 16.5 in the winter). Not sure how I feel about this. I ran with IRP premix and without and it didn't seem to make difference in the gas mileage.
04-02-2008, 06:37 AM
#295
Registered User
Can you explain how a higher flashpoint translates into a positive or negative attribute inside the rotary engine? I've seen this argument against synthetics again and again but I'm not sure it applies. It might even be that a higher flash point is better. All oil injected is going to carbonize eventually. There's no other way for it to get out.
First, in my 2007 RX-8 owner's manual, the reason cited for avoiding synthetics is cold starting, there may be others. I'm assuming that's a flash point issue. Having said that, rich mixtures of gasoline form more carbon in the exhaust. I'll assume that less of the carbon in the fuel is reacted with oxygen resulting in less carbon dioxide and carbon monoxide and more into just plain old carbon (the black stuff). One reason for this is plain old stoichiometry. 14.7 parts O2 required for complete combustion of gasoline at standard temperature and pressure. Perhaps another reason for this is lower temps in the combustion chamber.
Now combining the above and noting incomplete combustion (not making enough oxygen compounds) results in a carbon formation from hydrocarbon materials, that burning motor oil (a hydrocarbon) at a lower temp (or it having a lower flashpoint) may result in incomplete combustion (like gasoline), thus forming carbon deposits.
04-02-2008, 08:31 AM
#296
Registered
I'm not getting into the oil debate again since I've already won it in numerous other threads time and time again (along with the hydrogen and ethanol debates!) but I will say there is no valid reason to stay away from a good synthetic. The only thing left is the personal choice to do it. That's it.
If mileage went down when switching to Redline 10W40, it didn't do so because it was a synthetic. It did so based on the fact that the oil is thicker and harder to move. I know the older rotaries used much thicker oil but the Renesis has a really poor internal oil passage system. The passages are smaller and more poorly done than those in the older rotaries which means it is harder for oil to flow through them.
If mileage went down when switching to Redline 10W40, it didn't do so because it was a synthetic. It did so based on the fact that the oil is thicker and harder to move. I know the older rotaries used much thicker oil but the Renesis has a really poor internal oil passage system. The passages are smaller and more poorly done than those in the older rotaries which means it is harder for oil to flow through them.
04-02-2008, 09:33 AM
#298
Purveyor of fine bass
If mileage went down when switching to Redline 10W40, it didn't do so because it was a synthetic. It did so based on the fact that the oil is thicker and harder to move. I know the older rotaries used much thicker oil but the Renesis has a really poor internal oil passage system. The passages are smaller and more poorly done than those in the older rotaries which means it is harder for oil to flow through them.
04-02-2008, 09:37 AM
#299
Registered
I used to run straight 30W in my RX-7. Of course I'm also in Houston so I can get away with this. Just to add to the weight debate for the people who are paranoid about using the right one, I've also run 20W50 and even 5W20. Engine still runs strong.
04-02-2008, 11:11 PM
#300
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Interesting thread but twisting this into the synthetic versus dino oil debate is not correct because that same engine has run on both for long periods of time. There is a fair amount of carbon in the ports but compared to how much was actually made during all those miles, it is little. A sticky residue seem to have hold all those deposits there - was this the case, Paul? On the rotors, it looks like dry deposit - probably from premix and from detergents in the oil injected by OMP...
The only clear conclusion is the insufficient viscosity of the oil used that cause high, localized wear. Maybe the antifriction and antiwear components of the oil were not great either - those protect engines during start-up. Any oil or ester will drain in time from most of the surfaces. And there is no car engine oil that is ester - some synthetics contain some ester to improve polarity so some of the oil components can be soluble and stay in the oil, not precipitate out. Only in aviation they run pure ester oils and one should never ever use those in cars - seals in cars cannot withstand 100% esters and there is no need for them pure anyway. The additives in those oils are completely different chemically too. Also, oils do not burn inside combustion chambers because the time required for them to vaporise so it can burn is too long compared to the movement of the piston. Oils lubricate moving parts and are mechanically expelled from the combustion chamber into the catalyst. Most does not burn completely in the catalyst either and gets emitted as smoke (OMP injects tool little for us to smell oil in exhaust or see the characteristic blue smoke). Most of the deposits in the engine and the soot on tail pipes are from the gasoline, not the oil. Some premixes modify gasoline combustion to make it more complete, hence the soot is reduced (and is softer/easier to clean).
A fiber-optic videocam that can be used through the spark plug hole for different engines running different oils, at different mileages, would provide good data on the effect of premix, oil type, etc. Not as good as the rebuild photos but much more data can be collected during the engine's life...
I agree with the 10W-40 recommendation. I made it myself years back for NE US: 5W-30 in winter and 10W-40 the rest. I also used 2oz. FP60 and 1oz non-detergent motor oil as premix since after engine break-in, for the last 50000 miles. I did run engine break-in on 5W-20 dino (2000 miles), the rest are all synthetic blends of above viscosities (Kendal GT-1 for 20000, then Valvoline Durablend for 30000 miles). At 55000 miles I'll switch to full synthetic (same viscosities) and go from 3-4000 miles oil changes to 5-6000 miles changes. I ran 80% of the time Purolator PureOne oil filters. I'll keep premixing for the life of the car.
PS people trying to get rid of 5W20: mix it with the same brand 20W50 at 3:1 to get 10W-40 or so. Or 2:2 with 5W40 to get 5W30. Get creative, motor oils are actually compatible and the same brand has the same components in the same line of oils, just the amounts scale up or down, so... :o)
The only clear conclusion is the insufficient viscosity of the oil used that cause high, localized wear. Maybe the antifriction and antiwear components of the oil were not great either - those protect engines during start-up. Any oil or ester will drain in time from most of the surfaces. And there is no car engine oil that is ester - some synthetics contain some ester to improve polarity so some of the oil components can be soluble and stay in the oil, not precipitate out. Only in aviation they run pure ester oils and one should never ever use those in cars - seals in cars cannot withstand 100% esters and there is no need for them pure anyway. The additives in those oils are completely different chemically too. Also, oils do not burn inside combustion chambers because the time required for them to vaporise so it can burn is too long compared to the movement of the piston. Oils lubricate moving parts and are mechanically expelled from the combustion chamber into the catalyst. Most does not burn completely in the catalyst either and gets emitted as smoke (OMP injects tool little for us to smell oil in exhaust or see the characteristic blue smoke). Most of the deposits in the engine and the soot on tail pipes are from the gasoline, not the oil. Some premixes modify gasoline combustion to make it more complete, hence the soot is reduced (and is softer/easier to clean).
A fiber-optic videocam that can be used through the spark plug hole for different engines running different oils, at different mileages, would provide good data on the effect of premix, oil type, etc. Not as good as the rebuild photos but much more data can be collected during the engine's life...
I agree with the 10W-40 recommendation. I made it myself years back for NE US: 5W-30 in winter and 10W-40 the rest. I also used 2oz. FP60 and 1oz non-detergent motor oil as premix since after engine break-in, for the last 50000 miles. I did run engine break-in on 5W-20 dino (2000 miles), the rest are all synthetic blends of above viscosities (Kendal GT-1 for 20000, then Valvoline Durablend for 30000 miles). At 55000 miles I'll switch to full synthetic (same viscosities) and go from 3-4000 miles oil changes to 5-6000 miles changes. I ran 80% of the time Purolator PureOne oil filters. I'll keep premixing for the life of the car.
PS people trying to get rid of 5W20: mix it with the same brand 20W50 at 3:1 to get 10W-40 or so. Or 2:2 with 5W40 to get 5W30. Get creative, motor oils are actually compatible and the same brand has the same components in the same line of oils, just the amounts scale up or down, so... :o)