So its been years. What's the best oil and filter, Manuel fluid, differential fluid to use now adays on our FD's? thanks

Here's a pic of my engine bay.

 

Whatever you like as long as it's changed at a suitable frequency.

 

there are 3 parts to picking an oil.
1 is the viscosity. Mazda has a table of temps vs viscosity. most OEMs now skip the temperature table, as the engine runs at the same temp all the time, so its pointless
2. is the API performance level, for gas engines its an S with a letter, and Mazda's spec is old, we're on SN or SM now. there are SN+ or energy conserving ones, and you don't want to use that.
3. if there is a trade name, part number or other qualification. Mazda didn't bother, as the engine doesn't really care, but most other manufacturers have something.
you might also put the mineral vs synthetic in here, Mazda picked a mineral oil.

you need an oil that fits all three of these, and after that you're free to pick anything you want

 

I understand that the forum is much slower these days. But I’d still recommend the faq stickys and/or the search function. This is a bit like asking what’s the best beer. And should I get an import or domestic.

As for filters…if you’re a bit ocd and live near a Dealership OEM filters are always a safe bet.

As usual j9fd3s covered the basics well but I’d emphasize the “might” in picking mineral over synthetic ….unless you have a warranty. That debate can, and has been lengthy with no (imo) clear winner.
As mentioned above regardless of which oil or filter keep the interval for changing short(er) than you DD piston engine and monitor both the level and smell. Most all rotaries I’ve been familiar with suffer some fuel dilution over time.
Regardless I don’t let it get past 3k miles, but that’s just me.
Personally I see absolutely no reason NOT to use a good modern synthetic 75w-90 GL-4/5 gear oil over mineral.

And I think posting multiple threads with the same question is still kind of frowned upon.

 

I started using OEM RX-8 S2 (2009+) oil filters; they have a higher psi bypass setting.

As for oil, Rotella 15w40, VR1 20w50, Idemitsu 20w50, with a bottle of ZDDP+ on top
regardless of oil I change it at no more than 3000 miles to prevent fuel dilution

Trans/Diff I'm using Ford Mototcraft xt-m5-qs

Premix Idemitsu or Amsoil Interceptor or any quality JASO FD 2--stroke oil

 

It doesn't have to be complicated.

-10W-30 or 20W-50 conventional, brand is less important but preferably with higher ZDDP content.
-OEM Mazda filter
-Change every 3k

 

Living in the Miami area, I'd 100% stick with 20w50 engine oil all year round. Valvoline VR-1 is a great non-synthetic oil with high levels of Zinc. If you want to go the synthetic route, Idemitsu 20w50.

I'd never let an FD go 3000 miles on oil, especially if we're talking an original engine that has presumably loose clearances to help maximize blowby

Check your oil frequently to keep tabs on the color, smell (fuel?) and perceived viscosity. Recommend changing every 1500-2000 miles.

Nice tip on the S2 oil filters @neit_jnf

 

If you're running a catalytic converter, I'd avoid high ZDDP oils - they can screw it up.

 

N3R1-14-302 is the Mazda number, not sure aftermarket figured out there was a different filter, so there may not be one.
it ONLY fits the 2009-2011 Rx8.

 

I’ve been using that rx8 filter since early 2020 when my parts guy mistakenly put it in my box of parts. I never new it had a higher bypass pressure. Like some here I won’t get into the oil debate. You can use the search function to find your fair share of threads. I do like lucas hot rod oil which is high zinc, Smurf oil ( Valvoline vr1 ) and of course Idemitsu. I’ve used all three and like them all.

 

since i'm down the rabbit hole this is Mazda's oil spec. they do actually call out mineral oil, which is interesting.


and then the trans and diff

 

Yeah, and for all you new owners…be sure to wait for all 4.9 (or 5.4 ‘R’ model) quarts to drain before refilling with clean oil.
Another reason for short change intervals.

 

N3R1-14-302 Oil Filter By Pass rating is 20.3—26.1 PSI. Others are about 11-17psi.

If buying aftermarket replacements you have to verify the bypass rating, some replacements still have the lower rating.

 

Good info guys, thanks a lot!

 

if that value is hard to find, the application list works too, the Fram looks like this, which makes it actually cross about 3 different Mazda filters. the Skyactive filter is different again, so all of the 2012+ apps are wrong too

 

What does the higher bypass psi do for us? I’m not aware.

 

heavier oils when cold can bypass the filter, higher pressures at higher rpms and also if the filter is becoming saturated / due for a change it can bypass.
The higher bypass pressure setting provides better filtration in these scenarios.