Which is better? Redline or Royal Purple?
 

Gonna be changing my tranny and differential fluids soon... so, So which is better? Redline or Royal Purple? Anyone?

Royal Purple 'Max-Gear' is very highly rated, but mostly by racers, who care more for performance than longevity.

Redline is, I think, a step above. Best reputation in the oil business, bar none.

We are blessed with a drain plug, so never have to take off a diff cover to change the oil, but 'domestics' usually do, and you can see an immediate difference on the gears. Check a differential with Redline, even after it has sat overnight - the gears still have a thin red coating of oil on the surface!
Tenatious stuff, and try not to get it on your mitts as you change it - it will stick to skin the same way.
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doc

Most of my friends that have owned RX-7s have used Royal Purple.. they swear that's the ONLY thing to use. :P

I used Royal Purple MaxGear in my RX-7 (tranny and diff) for years with nothing bad to say about it. I never compared it to Redline, however I've never heard of anyone complaining of troubles with it. Or Redline for that matter...I don't think there's a wrong answer here. Either one is good stuff, so if one is significantly more expensive or harder to find...get the other one.

It is a logical fallacy to infer that Redline is better in terms of longevity because racers use Royal Purple and racers are not as interested in that trait.

jds

Yeah, they're pretty similar - I think you're really splitting hairs trying to figure which one's best. They're both lightyears better than plain gear oil.

I usually just get whatever's easiest or cheapest to get - either Redline or Royal Purple. Both are excellent products.

Dale

i have used royal purple on my rx7's
never tried redline before
but some viper guy i knew used it.

Royal Purple user over here. Royal purple Synchromax in the gearbox and Max Gear in the diff. Smoother shifts and less noise from the rear end.

Tony says, "Two thumbs up!!"

Royal Purple makes some good stuff. My overall favorite is Amsoil though.

as you can plainly see, all great products. get the cheapest one.

I already ordered the Redline. :D

I've got redline on the way too :)

I put Red Line (it's two words people and here's the link http://www.redlineoil.com/) in transmission / differential.
rx8cited

I got Royal Purple in both DIff and tranny. Got rid of that whirring noise the car made when cold, adn feels nice and smooth.

Tony: Acording to the guys at RP, do NOT use Synchromax in the RX-8's diff. Let me quote:

"The differential needs a gear oil - like our MaxGear 75W90.
DO NOT USE Synchromax in the differential. It is the fluid consistency of an ATF and your differential will not last."

According to:

David Canitz
Tech Services Manager
dcanitz@royalpurple.com

Ok, my understanding is to use Royal Purple MaxGear 75W90 in both DIff and tranny.

What is the exact Red Line product(s) to use? MT-90? 75W90 Gear Oil? I went to their website and got myself all confused...

Thanks for the tip Genom, but re-read my post:

I appreciate your concern, though. :)

https://www.rx8club.com/attachment.p...chmentid=26627


BTW gear oil stinks :D

For Red Line, use MT-90 in the tranny, and 75W90 Gear Oil in the diff.

Edit: Or do what I did and use the RP MaxGear 75W90 in the diff, and Red Line MT-90 in the tranny...

Ok, thanks guys. That's what I kind of thought. Good to know for sure. :D

Thanks again!!!!!

And agreed, gear oil stinks big time!

as anyone used redline water wetter..?

I added some (small bottle) and noticed no difference

I used a 12oz bottle and notice no difference in the temperature guage or performance of the car.

I wonder how many degrees each tick mark on our temperature guage corresponds to?

BTW it is Red Line (two words) if you care ;).

rx8cited

If your using water wetter you need to purge your cooling system first to get the right mix since it uses way less antifreeze than normal. You also wont see a difrfernce in the gauges, but the car should run better in high heat stuff like autocrossing and HPDE events.

Not necessarily for my use. 50/50 is okay as I'm not trying to maximize the temperature drop.

Here are the directions from thier data sheet:

"USE DIRECTIONS
One 12 ounce bottle treats 12-16 quarts of water or a
50% ethylene or propylene glycol solution. In smaller
cooling systems, use 4-5 caps per quart. Add directly
through the cooling system fill cap into the radiator or
into the overflow tank. Do not open a cooling system
while hot. For best protection for aluminum, replenish
or replace every 15,000 miles. The anti-scaling ingredients
in Red Line WaterWetter® allow its use with
ordinary tap water. However, using with distilled or
deionized water will accomplish some scale removal
in the cylinder head area. Plain water with or without
WaterWetter® should not be used in cooling systems
containing magnesium - antifreeze should be used -
with WaterWetter®. For maximum temperature
reductions use the most water and the least
antifreeze possible to prevent freezing in your climate.
Even in summertime the use of air-conditioning
can blow freezing air through the heater and cause
freezing of the heater core unless approximately 20%
antifreeze is used. Red Line WaterWetter® is available
in 12 ounce containers."

rx8cited

Hey guys.. here are some measurements that I took from my CANScan regarding the coolant temp.. I just so happened to also be tracking my air temp at the time. I plan on adding water wetter and then running the test again to see if there is any difference...

Here are my results so far..

The temperture was 58 to 60f.

The spike that you see after 10 minutes was me pulling over for a few minutes to test how hot it would get just ideling.. Gets darn hot :)

After this brief stop, it returned to normal.

I am hoping to see my car run at 170 or lower consistently.. we'll see :)

Cool, Dave. If it works, then I'm gonna get Water Wetter, too.

I used the Red Line MT-90 in my gearbox (and 75W/90 in my diff) and noticed no difference at all actually, my first to second shift is still a bit notchy. BTW, before using Water Wetter, read this thread and follow the links to another few threads. Some cars will run too cold with Water Wetter.......

Gomez.

Gomez,

I forgot about that thread. I think that is a totally different issue that even piston engines have. I was going down a snow mountain last year in my other car (piston engine car) and I was surprised to see the engine temp way down low for over 30 minutes. So it's not something specific to the rotary.

This may be applicable

https://www.rx8club.com/series-i-tech-garage-22/100%25-better-shifting-44847/

I have royal purple in the engine and red line in the tranny and LSD. Couldn't be happier.

I use Royal Purple 5w20 in the engine, Red line MT-90 in the tranny, and Red Line 75w90 in the LSD..

Make sure you DO NOT get the Red Line 75w90ns since it's for non-limited slip differentials and you'll hurt your 8 ;) Most places have both right next to each other and it's easy to pick up the wrong one off the shelf.

Thanks Gambit, I had read that thread before but you've prompted me to do a bit of digging deeper into the "bob is the oil guy" forum. There's definately a core theory on that forum that a 50/50 mix of MT-90/MTL is the way to go for notchy transmissions in moderate climates. Straight MTL for those who have a lot of snow about......

Must track myself down a bottle of MTL....

Gomez.

No prob...I had that one saved in my subscribed threads for when it comes time for me to change my fluids...only got about 1500mi on it now

I had talked earlier in that thread in response to StealthTL that I might try the 50/50 but it seems my MT90 is coming around, loosening up in the mornings as I put more miles on it.

Maybe there is a better thread for my results.. If you guys suggest one I'll put it there.. if not.. then i'll just post my new graph tonight here.

thankx!

dave, I think your results are important enough to warrant a new thread. Maybe you can put the before and after in BOTH threads.

The operating temp of the Rotary Engine is regulated by the coolant and oil thermostats at 180 F, unless the Renesis has a different thermostat. Adding Water Wetter will not change that, what it's supposed to do is improve the transient temperature changes. For example, it may make that spike go down to 180 faster.

Ohh ok.. I'll test it out tonight and run the same pattern that I did and we'll see how it effects it..

Should be interesting... I'll create a new thread if it's that amazing :) Maybe I will anyway just to let people know it didnt help me that much....

Yeah, it would be awesome to see that peak go down faster on a graph. Sorry but I get excited about graphs and science.

Dave, probably better to post your results in this thread . The data will be overshadowed in this thread about Red Line oil....

Gomez.

OK.. I updated that other thread.. doesnt look good for wetter so far..

Sorry to resurrect this thread, didn't want to start a new one unnecessarily. My car just ticked 30k miles and I'm going to get the trans and diff fluid changed. My best friend is a master mechanic and they use only BG fluids at his shop, so it's going to be Synchroshift 2 in the trans and UltraGuard for the rear. I know BG Ultraguard comes in 75w90 but it may be available in other weights, i called Mazda and asked them what they use for the rear and they said Mazda's factory rear diff fluid is 75w140 but 75w90 or 75w120 would work just fine. I've read countless threads on which fluid is better but it usually involves Redline and RP and mentions nothing of BG fluids (minus a member that sells it apparently), so i wanted to see if anyone had any experience with synchroshift 2 and its cold and warm weather properties regarding the RX8. I had synchroshift in my audi and i remember it being really tough to shift in extremely cold weather but once the trans was warm things got really smooth and this was with an original trans/flywheel/clutch with 150k miles on it. I can only imagine that with a practically new transmission i shouldn't have any problems, but i figured i would proceed with caution since i would like to avoid replacing the trans in the future if i can.