When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The UOA from 6/19/23 at 41k miles was the one I was talking about.
The final 2 are VR1 20w50. All of these are 20w50. The one with the high lead was Walmart ST. The rest are GTX 20w50 SP.
I had thought that the Mazda rotary bearings were happy as long as there was sufficient PSI and oil viscosity. The difference with the VR1 was unexpected.
GTX had been getting more and more weak with an anemic add pack and I thought switching to the cheaper ST was an easy move. Wrong, I was.
This is a rebuilt engine with all used bearings, rotors and shaft.
Something which recently came to mind was the variety of jdm specific rotary oils offered by RE, Fujita, Mazdaspeed, etc available from the 90's-10's. It seems they're NLA but I was wondering if there was anyone here who has direct experience and in what type of environment and for how long. I personally would also be really curious to see how these oils perform by today's standards and what the analysis results would yield.
Currently using millers ee performance 5w-40 (mostly because im a fan of the nt technology) will use it for one, maybe two more intervals so i can see how the wear metals stablize.
engine was rebuilt in 2016 by rotary revs in the uk. The car has since done about 20k kilometers. I think the car had been sitting for a while before i bought it. aswell as the previous oil being used for a really long interval.
First oil is from previous owner, not sure what it is. Was suspicious that the magnetic drain plug might have caused elevated iron and chromium readings, as it appeared to have corroded. got a new plug with the new oil.
Car already had sohn adapter installed. currently using motul 710 in sohn + premix in tank. as it's jaso fd spec and catalytic + oil injection safe.
Heres the kicker. after im happy the wear metals have stablized. i'll probably swap to a motorcycle oil! Why? Well atleast on paper they're safe, as they have both the right viscosity and specs for the rx8. But they are also formulated for gearboxes. So im hoping it could prove benefitial for the bearings and stationary gears.
Specificlly thinking about using rymax motrax 4t fs 5w-40 api sp. wich is supossedly also suitable as a premix oil?!? and claims to be catalytic and oil injection safe. wich makes it sound like the ideal oil for a rotary with omp. i've sendt a email to rymax asking if it's really suitable as a premix, but have yet to hear anything from them.
Thoguht you guys might find this intresting. i asked blackstone labs if they could show me their universal averages for each of the mazda rotaries.
Samir was very helpfull and put together this spreadsheat. After looking at most if not all uoa posted online. i suspected that kevin's philosophy of following the mazda recomendations prior to the stricter emission laws taking place. (so rx7 spec basiclly) might be spot on for that the renesis need. And the numbers from blackstone seem to confirm this
There isnt really a huge sample size, for either engine. and the rx8 is by far the most represented. but it's intresting to note that it is also the highest in wear.
if we disregard the winter number (0w 5w 10w 20w etc) and focus on the viscosity at oppreating temps. Then (and i'll make a bold assumption here) the average for the rx8 is somewhere around 35.
Black stone wasnt able to share and average of viscosity for all their samples. and i assume one would have to go through all of them manually in order to get an average.
regardless, it is still the case that you must analysie your own oil to find out if your oil theory works.
PLEASE NOTE: im not sure of the average oil interval for each engine. but i belive on average the rx8 intervals are slightly longer than the 13b.
Last edited by DailyDrivenrx8; Feb 22, 2025 at 05:27 AM.
Was concerned about fuel dilution, considering the long time but they say it’s looking good Engine is a Mazda Reman with 15K miles. Chromium and iron ok?
Was concerned about fuel dilution, considering the long time but they say it’s looking good Engine is a Mazda Reman with 15K miles. Chromium and iron ok?
just curious but how is your pcv setup? i founf both my rx7 and rx8 was venting to atmosphare, once i rerouted back into the intake. i noticed i had much less fuel in my oil
Was concerned about fuel dilution, considering the long time but they say it’s looking good Engine is a Mazda Reman with 15K miles. Chromium and iron ok?
No. Too much chrome and iron in my opinion. Should be single digits or in the case of chrome noise only (1ppm) Silicon too is high. K/N or other than stock filter?
If this were mine I would:
Premix (heavily) and 20w-50.
No. Too much chrome and iron in my opinion. Should be single digits or in the case of chrome noise only (1ppm) Silicon too is high. K/N or other than stock filter?
If this were mine I would:
No. Too much chrome and iron in my opinion. Should be single digits or in the case of chrome noise only (1ppm) Silicon too is high. K/N or other than stock filter?
If this were mine I would:
Premix (heavily) and 20w-50.
This was on a k&n filter 10w-40 and idemitsu premix. 20 months and 3,600miles on oil.
running stock cat so not sure I can premix too much, been about 120-150cc per 12-14gal fillup
This was on a k&n filter 10w-40 and idemitsu premix. 20 months and 3,600miles on oil.
running stock cat so not sure I can premix too much, been about 120-150cc per 12-14gal fillup
The Idemitsu premix will burn clean, don't worry about the cat. The stock OMP/sump oil degrades it more than 2t oil.
Too little premix in my view, 1oz per gallon at least with OMP. I prefer 2oz per gallon though, especially on a new engine you would like to preserve. Most will say that is too much. I say it's not, at all. Going to that ratio is still very lean compared with the rest of the world of total-loss engines. The OMP delivery is minimal for street driving, so that can be ruled as "extra". These engines don't "lose compression"-- they wear out. Lack of lubrication (which also means cooling) is a primary reason for this in my opinion.
Put the K&N away and go back to stock airfilter. You will thank yourself later.
Thanks. I will look into increasing premix, but have to ask do you have long-term experience with an RX-8 with cat running premix?
just to clarify, though, I am using a stock air filter(btw who knew that the RX-8 uses the exact same air filter as a Dodge Viper). A K&N oil filter only.
SoCal can get extremely cold. This oil sample was from when I lived in the high desert where fall/winters would regularly drop between 29 to 35°F.
Originally Posted by DailyDrivenrx8
just curious but how is your pcv setup? i founf both my rx7 and rx8 was venting to atmosphare, once i rerouted back into the intake. i noticed i had much less fuel in my oil
Thanks. I will look into increasing premix, but have to ask do you have long-term experience with an RX-8 with cat running premix?
just to clarify, though, I am using a stock air filter(btw who knew that the RX-8 uses the exact same air filter as a Dodge Viper). A K&N oil filter only.
SoCal can get extremely cold. This oil sample was from when I lived in the high desert where fall/winters would regularly drop between 29 to 35°F.
Right, get rid of the K+N, this is likely where the silicon (sand is coming from).
I run 20w-50 in AZ and it gets to low 20s.
The Aussie oil chart for the RX8 shows 20w-50 down to 20 degrees F, if you need to see it. This is the same chart for all rotaries going back to the beginning.
That 2t oil will not foul your cat. I have miles on it this way but not as much as you would like to feel confident. If you look up the properties of this oil it has much less inorganic and metallic AW compounds than regular 4t motor oil. It cant ruin the cat. Like I said the OMP does more to degrade the cat than 2t oil at 15:1 would do. These are things people have been misinformed about and traded info back and forth since the early days. I believe this is a 300k + mile engine when maintained correctly, which does not mean factory recommendations.
Last edited by kevink0000; Jul 30, 2025 at 01:57 PM.
here is my latest oil analysis. this is from the winter months. where i also ave been having an issue with stuck brakes. i belive this increase in resistance might have had an increase in wear. winter is also harsh on engines here in norway.
my plan is to get 3 oil analysis done on millers 5w40 ee performance. (i have sample 3 sitting on a shelf ready to get shipped) and to then switch to a motorcycle oil (wich i have last oil change) i choose motul ngen 7 as it meets jaso ma-2 is 5w-40 and the website listed it as api sp (was infact api sn so i got a rebate) i would not recomend api sn in any rotary, as the high calcium content will compete with the zddp. (althoug it is uncertain exactly how much zddp a rotary needs)
Why motorcycle oil? motorcycle oil is formulated for engines that share their oil with the gearbox, and thus must tolerate extreme pressures. such extreme pressures can be found in the stationary gear of a rotary. motorcycle oils must (as part of the jaso ma2 spec) meet one of 14 other oil specs (for example api sp) so since it meets a relevant spec for the rx8 and is formulated for extreme pressures, it might be able to reduce wear from the stationary gear.
obviously i have to do 3 samples of motorcycle oil to determin if there is any benefit. but so far my car seems happy with it. then again i also just fixed and exhaust leak right infront of a o2 sensor so that could also explain why it runs better.
Using motorcycle oil sounds interesting. Meanwhile motorcycle guys are using diesel oil 15w-40
i belive that might be because of the misconception that diesel oil always has more zddp in it. Not to mention that to much zddp will cause excessive wear. Where as my theory is that Jason ma2 oil will either have base oil blends or addetives to deal with the gearbox. Mobil 1 often has alkylated naphetelene in their base oil blends. And I wonder if thatbmight be the reason the mobil 1 0w-40 is showing such low wear metals in the reports shared here
i belive that might be because of the misconception that diesel oil always has more zddp in it. Not to mention that to much zddp will cause excessive wear. Where as my theory is that Jason ma2 oil will either have base oil blends or addetives to deal with the gearbox. Mobil 1 often has alkylated naphetelene in their base oil blends. And I wonder if thatbmight be the reason the mobil 1 0w-40 is showing such low wear metals in the reports shared here
I would be looking for different oil/premix amount. Too much iron and chrome in my view. Your engine is taking itself apart, like most of these do when set up/run close to stock.
Try a 40w min automotive oil, (generally better film strength and AW additives than MC oil, due to wet clutch concerns in MC oil), and premix 2oz per gallon min.
i belive that might be because of the misconception that diesel oil always has more zddp in it. Not to mention that to much zddp will cause excessive wear. Where as my theory is that Jason ma2 oil will either have base oil blends or addetives to deal with the gearbox. Mobil 1 often has alkylated naphetelene in their base oil blends. And I wonder if thatbmight be the reason the mobil 1 0w-40 is showing such low wear metals in the reports shared here
I personally think m1 0w-40 is a good oil for most normal engines. The Mazda rotary needs something better(for it).
Using motorcycle oil sounds interesting. Meanwhile motorcycle guys are using diesel oil 15w-40
Yes to this. I've been using both Shell Rotella 15W40 T4 (conventional; https://rotella.shell.com/en_us/prod...rotection.html ) or Delo 15W40 (blend and API-SN grade; https://www.chevronlubricants.com/en...sb-15w-40.html ) in both my 2000 Honda ST-1100 and 2001 Kawasaki KLR650 since 2002-ish timeframe. 10W40 is specified for both but sing this for two reasons: (1) higher zinc ZDDP levels as both do not have a catalytic converter and (2) cheap.
I would be looking for different oil/premix amount. Too much iron and chrome in my view. Your engine is taking itself apart, like most of these do when set up/run close to stock.
Try a 40w min automotive oil, (generally better film strength and AW additives than MC oil, due to wet clutch concerns in MC oil), and premix 2oz per gallon min.
i've been using 5w40 for every oil change. (first report appears to be 5w30 from previous owner) i only just put in a 5w40 that meets jaso ma2. so i dont have any numbers on it yet. your suggestion about increasing the premix is intresting thoug. i might try it after the next oil change. so i dont introduce another variable to my motorcycle oil experiment
Yes to this. I've been using both Shell Rotella 15W40 T4 (conventional; https://rotella.shell.com/en_us/prod...rotection.html ) or Delo 15W40 (blend and API-SN grade; https://www.chevronlubricants.com/en...sb-15w-40.html ) in both my 2000 Honda ST-1100 and 2001 Kawasaki KLR650 since 2002-ish timeframe. 10W40 is specified for both but sing this for two reasons: (1) higher zinc ZDDP levels as both do not have a catalytic converter and (2) cheap.
higher zddp then what? loads of engine oils will have zddp levels above 1000ppm. but you mention that you use api sn grade? api sn hast the highest calcium content of any api grade. calcium competes with the zddp, clacium can also cause low speed pre ignition. wich is why they made api sn+ then later api sp (both with lower clacium contents.
also. if you compare the zddp contents and wear metals from all of these reports. there doesnt seem to a strong correlation between wear and zddp levels. (for the rx8 oil reports in this thread atleast)
