ok im reading the FAQ and its very misleading haha

According to Mazda:

In starting and operating temperatures below 20F, use 5W30
In starting and operating temperatures between 0F and 80F, use 10W30.
In starting and operating temperatures above 30F, use 20W50

Conventional oils 10W40 and 10W50 have been shown to increase deposits in many high reving motors and are generally no longer recommended.

and also

Yes and no. Mazda offically does not recommend the use of synthetic oils in rotary engines, however, it has long been proven that the better synthetics (Redline, Amsoil, Neo, Royal Purple, Mobil1) are perfectly fine to use in a rotary engine, and will generally result in a 1 to 2% horsepower gain. However use of poor quality synthetics (like Valvoline, Castrol Syntec, Havoline, Etc) will result in build up due to high ash content left from these oils when they are burned. That is why Mazda did not recommend synthetics, because the couldn't pick favorites.

I live in l.a. so temps get high, but i dont want build up and i dont want synth ruining my engine i've heard bad things about all synths....

 

20W50 Castrol GTX or Mobile(mineral) are just fine. Synthetics while superior do not pay for themselves. We've done the math before throughout a car's life and you can pay for an engine rebuild with the savings of stick with mineral oil compared to synths. So yes they are worthless in your engine.

Use synths in your diff/tranny.

 

yippy an answer, my dipstick was just below L so i know its time haha.

 

yeah, i run castroll GTX 20w50 and ive never had a problem

 

I call BS on the FAQ because my owner's manual and FSM call for 10w-40 for year round use. No risk of deposits or problems using an oil with a 30 or even 35 point viscosity spread. All 4 stroke oils will create ash when burned via the MOP, if that weren't the case then we wouldn't have 2 stroke oils. With that said, I have never had any carbon problems (or even a blown engine) by 10W-40 year round. And yes, I'm on my 4th FC since 1986.

As soon as it cools down, I'll probably switch from 10w40 to a 5w-40 oil to help with the colder weather starts.

PS All of the dipsticks complaining about fuel economy could probably benefit from an extra 1-2 mpg using a lighter visocisty oil. Castrol GC Synthetic comes in a Ow-30 weight and would be almost ideal year round use if you don't mind paying 5 bucks a quart. Its viscosity is on the upper end of a 30 weight and is almost as thick as some 40 weights. It is a Group III oil and is called synthetic but everybody knows that true synthetics are Group IV and Group V base stocks.

 

you must be new, but Icemark is RARELY (if ever, which i doubt) wrong.

 

I'm not going to disparage Icemark but he obviously isn't a tribologist. I'd get into the details but another postr tried to educate the ignorant masses earlier this year by highlighting the various oil specs was ridiculed for posting about alphabet soup.

No, I'm not new. I am a fairly competent individual when it comes to repairing vehicles but I do like to boast that I never had joined the brotherhood of a blown rotary engine and do not intend to do so anytime soon. I do know that the majority of folks here have some unexplainable and unhealthy obsession with 20w-50 weight oils for their rotary engines. Kinda makes me wonder why Mazda calls for 5w-20 oils for the RX8.

 

I am one of the 20x50 obsessors and after 45kmi and 1yr of driving my FE I am not likeing the 5w20 synthetic treatment that Mazda is using in the FE or how mine has been doing with it. If I don’t sell it I will rebuild it and switch to RP 20x50. I kinda have this deal thing where the dealer pays for my oil changes :-/ Actually they robed it out of me on paper work.

 

I feel another oil debate brewing......I always get a little rumatizm in my left knee when a big is coming....

*looks over shoulder for Icemark*

 

I just bought an 89 GXL the other day and the previous owner only used 5W-30. I live in Nor. Cal so it gets pretty hot, can I keep using Castrol GTX non-synthetic 5W-30 motor oil or should I do an oil change soon and switch to 10W30 or 20W50?

 

haha oh no looks like i started a war haha. I got some 20-50 to put it up to full until i have time for an oil change.

 

lol....i was gunna rock royal purple...so i guess its a bad idea..and no i dont mind spending it but if it isnt going to help me out...then....(i live in San Antonio TX.) usually 90degrees so my best choice?

 

Castrol GTX 20w50 changed every 2,500 miles works for me.

 

I run RP everywhere but I am someone who does not take oils lightly ive spend over 15 grand on parts for rebuilds just from figure out what blend works the best what full synthetic was trashing my motors and why one without molly has kept them together until they needed freshened and so on.

 

Casrtol GTX 20w50 in TII and vert. Both changed every 1500 miles.

 

My engine buildr uses Mobile1 15w50 in every car he owns or rebuilds so thats what i continued using. No problem so far and even though someone mentioned something about heavier oils, it actually seems alot thinner/lighter than the 10w30 in my other cars.

 

nah, I have made my point of conventional petrol based 10W40 and 10W50 oils should not being used for modern high rev'ng vehicles plenty of times before.

Homebrewer, however believes in what he likes. I (and many people that have read/studied oils and how they have changed over the last 20 years) just happen not to like all the extra polymers added to the weight oil he uses. I will not try (the least bit) to change his mind about the oil weights he uses- his mind is not open to the arguments about it.

Nor I will not get into another debate with him on it. He can use anything he wants and if everyone else was a educated consumer (or even had the ability for to search)- there wouldn't be threads like this anymore.

I know what I use in my cars. Since I do all the work on my cars myself (as I don't trust most professional mechanics as far as I can throw them to do the job right/professional) I know what works for me. I can say without any doubts that Castrol GTX 10W30 and 20W50 work without fail or fault in 84-95 rotary motors.

 

I run 20w50 castrol gtx year round. It gets into the 20s in winter, but I rarely drive the car when its cold out anyways.

 

i run castrol syntec 5/50. but then, my MOP is set up different so im not burning it.

before i changed the MOP, i ran gtx 20/50 summer, 10/30 winter

 

5W when starting above 0F is a little thin... you may be having increased wear depending on the shear stability when cold.

 

I think its funny how many people say synthetic isn't worth the price difference, but they change their mineral oil twice as often as they need to.
I change mine every 3000. There has never been a time that the oil didn't come out of the car exactly the same as it went in, color and (at least the apparent) viscosity. I have 120k on it and my compression is still perfect. I know I don't have the boost monster setup like some of you guys do, though. But still I think lots of people just like doing it, so they change it alot. Like the guys who run premium through their NAs because they perceive a benefit in paying for more expensive gas. If the oil hasn't lost viscosity, the additive package is still doing its job, and the oil is still physically clean there isn't any reason to change it any more often than necessary, just to throw away perfectly good oil.

Only my opinion.

 

hmm if someone could contest that your point (not saying ur wrong wanna see the other side of that battle..)..cuz yea its been 2k coming close to the oilchange time and my oil is PRISTINE. it does feel cult like to follow this golden rule of changing the oil every2.5k ill do it no problem i guess but if it isnt detramental to the car in anyway...then i wont do it...BUT currently im not convinced that i shouldnt until some pro tells me so......im still in limbo as to what i should use(average local temps of 90degrees or so...) so i mean right now im using quakerstate...i dunno ill use mobil 1 synthetic next time around and see how things go....

 

20w50 will be just fine, used for 12 plus years in delivery in tennesse and kentucky wih high temps, never had a problem, changed oil about every 3 to 5k and never had a problem with the engine, mazda says to change at 7500 so even thats a little early, plus if you burn a quart every 1k, then really all you need to do is change the filter every three, and keep going!

 

I actually recommend oil changes of 3K for Turbos and 5K for non turbos and anytime the engine is flooded, when using good quality conventional oils like Castrol.

Any more than that is a waste of money, and no added protection.

Now if you are using some of the bargin basement brand .99 a quart oils- well then you probably would want to change more often.

 

heh good luck finding $.99 per quart oil anymore :P

even the cheap stuff around here sells for ~$1.20