I'm confused about which differential fluid to use :(
04-30-2017, 08:56 AM
#26
Enjuhnear
Went back with some slight edits to clarify things here and there.
On engine oils: as strongly as I feel about Castrol GTX for my own vehicle, I have to admit that the owner's manual isn't that strict. All it says the car wants is an oil with the API/ILSAC "starburst" symbol, which AFAIK just means API SM Energy Conserving and ILSAC GF-4. Plenty of good oils carry those approvals -- or better, e.g. API SN/ILSAC GF-5. So, if you chose to just pick up whatever has those approvals, I'm not gonna say you did anything wrong. I'm probably more conservative than most.
Quick caveats here.
Yes, if people can use the product for years without issue, that says something -- though I'd be careful, because "I've never had a problem" is one of the most meaningless statements in the automotive world.
Also, if your engine is breaking the oil down that badly... yeah, changing it frequently will help, but you'd still be better off with something more shear-stable. That's more in line with what Steve was saying, I think; not that RP is bad stuff by any means, but that other products are better, or just comparable and cheaper.
On engine oils: as strongly as I feel about Castrol GTX for my own vehicle, I have to admit that the owner's manual isn't that strict. All it says the car wants is an oil with the API/ILSAC "starburst" symbol, which AFAIK just means API SM Energy Conserving and ILSAC GF-4. Plenty of good oils carry those approvals -- or better, e.g. API SN/ILSAC GF-5. So, if you chose to just pick up whatever has those approvals, I'm not gonna say you did anything wrong. I'm probably more conservative than most.
Quick caveats here.
Yes, if people can use the product for years without issue, that says something -- though I'd be careful, because "I've never had a problem" is one of the most meaningless statements in the automotive world.
Also, if your engine is breaking the oil down that badly... yeah, changing it frequently will help, but you'd still be better off with something more shear-stable. That's more in line with what Steve was saying, I think; not that RP is bad stuff by any means, but that other products are better, or just comparable and cheaper.
04-30-2017, 11:44 AM
#28
Enjuhnear
04-30-2017, 12:34 PM
#29
Registered
On engine oils: as strongly as I feel about Castrol GTX for my own vehicle, I have to admit that the owner's manual isn't that strict. All it says the car wants is an oil with the API/ILSAC "starburst" symbol, which AFAIK just means API SM Energy Conserving and ILSAC GF-4. Plenty of good oils carry those approvals -- or better, e.g. API SN/ILSAC GF-5. So, if you chose to just pick up whatever has those approvals, I'm not gonna say you did anything wrong. I'm probably more conservative than most.
04-30-2017, 03:51 PM
#31
Enjuhnear
Gotcha, yeah I've got an S1 over here with about 80k on the odo.
04-30-2017, 04:17 PM
#32
I'm pretty sure there's a few different versions of the owners manual with different literature in regard to this depending on what year/region/etc. In my 04 the manual was pretty damn strict about using 5w-20. Was quite annoying as I didn't know nearly as much as I do now, and had to search around town for the stuff. I've seen quite a few different versions of what the RX8 manual lists as acceptable after searching through these boards though.
FWIW, mine's strict about 5w-20 as well. That's literally the only grade listed for any temp range.
05-01-2017, 10:04 AM
#33
The SN specs are better than oils in 2003 when Renesis came out.
I still think that this engine isn't nearly as hard on oil as say German cars.
My BMW X1 computer tells the engine to restrict cooling so it can get up to 236 deg for more effficiency; the RX8 will be toast near that temp.
So, I run an easy to find great oil: Mobil 1 0w40; closer to 40 weight at most temps.
Rear differentials are even easier to lube; a synthethic 75w90 GL-5 which lasts a long time since no combustion gases. It has lots of high load pressure additives like sulfur compounds.
We've been over and over this about 5w20 not being thick enough for those stationary gears.
Yeah, 5w20 can work, but something thicker is better.
A guy on here, Squidward, quit oil and filter changes at 50k miles, and ran 80k more miles like that before new engine.
I'm at 5 years and 6k miles; should I change now?
I still think that this engine isn't nearly as hard on oil as say German cars.
My BMW X1 computer tells the engine to restrict cooling so it can get up to 236 deg for more effficiency; the RX8 will be toast near that temp.
So, I run an easy to find great oil: Mobil 1 0w40; closer to 40 weight at most temps.
Rear differentials are even easier to lube; a synthethic 75w90 GL-5 which lasts a long time since no combustion gases. It has lots of high load pressure additives like sulfur compounds.
We've been over and over this about 5w20 not being thick enough for those stationary gears.
Yeah, 5w20 can work, but something thicker is better.
A guy on here, Squidward, quit oil and filter changes at 50k miles, and ran 80k more miles like that before new engine.
I'm at 5 years and 6k miles; should I change now?
Last edited by 40w8; 05-01-2017 at 10:14 AM.
05-01-2017, 10:50 AM
#34
A properly broken-in NA engine from Mercedes or BMW... I'd bet on the Renesis being harder on oil. Some of the recent(-ish) turbo engines definitely might give the Renesis a run for its money though. Thinking of the original N54, the higher-output versions of the N20, the N63, etc. And of course most M engines.
05-01-2017, 10:58 AM
#35
SARX Legend
iTrader: (46)
The oil (M1 0W-40) in my 335i (N55) does about the same (comparing reports) as it does in my RX-8 and it typically runs about 40F higher than it does in my 8. So I would say that the Bimmer is harder on it in that respect, but it doesn't show that in the used oil analysis.
05-01-2017, 05:40 PM
#36
I suspect this depends on which German car you're talking about.
A properly broken-in NA engine from Mercedes or BMW... I'd bet on the Renesis being harder on oil. Some of the recent(-ish) turbo engines definitely might give the Renesis a run for its money though. Thinking of the original N54, the higher-output versions of the N20, the N63, etc. And of course most M engines.
A properly broken-in NA engine from Mercedes or BMW... I'd bet on the Renesis being harder on oil. Some of the recent(-ish) turbo engines definitely might give the Renesis a run for its money though. Thinking of the original N54, the higher-output versions of the N20, the N63, etc. And of course most M engines.
05-01-2017, 05:47 PM
#37
The oil (M1 0W-40) in my 335i (N55) does about the same (comparing reports) as it does in my RX-8 and it typically runs about 40F higher than it does in my 8. So I would say that the Bimmer is harder on it in that respect, but it doesn't show that in the used oil analysis.
I read a report where someone ran oil like 0w40 20k miles, and it didn't look like it did damage, but the vis was a little higher.
I'd do 10k mile oil changes in BMW X1 and RX8, but I'm not doing many road trips anymore.