What oil should I use in my FD? The manual says mineral and the oil companys says syntethic. What are you using?

 

There are good reasons to use both types. Mineral works fine and is cheaper to change often. Synthetic offers more protection and (supposedly) lower operating temps, but costs more and you should still change it nearly as often in rotary applications.

Synthetic works fine in rotaries, counter to what the owner's manual says, as proven by millions of oil-trouble-free miles driven by your fellow forum members. Mazda even recently said it was okay to use synthetic in rotaries from one report I heard.

Use 10W-30 in the winter or if you live somewhere that gets cold. Many people run 20W-50 when it is warmer out. I used Havoline mineral oil and now use Royal Purple synthetic (in the quest for lower temps and better protection). Mobil 1 is another good choice for synthetic and many people use Castrol GTX mineral oil, too (though I have heard a few rumors about Castol not being that great). Pennzoil and Quaker State are supposed to be the worst mineral oils, and 10W-40 is generally a bad weight -- avoid these.

Change the oil often (every 3 months or 3000 miles or less). Use a good filter like the ones from Mazda, Purolator, or AC Delco (or the fancier Purolator PURE-ONE, K&N, or Mobil 1). Use the larger filter from earlier rotaries because they are bigger and easier to find.

I am sure you'll hear more opinions. These are my opinions after reading the opinions of many others, and various reports on the topic.

Here are my recommendations in a nutshell:
- Mineral: Havoline 10W-30 or 20W-50 (hot climate) & Purolator PURE-ONE filter
- Synthetic: Mobil 1 oil & Mobil 1 filter
- Synthetic #2: Royal Purple Racing oil & PURE-ONE filter

-Max

 

i say find the cheapest 10w-30 you can and change it every 500 miles. change the oilfilter every 1000 miles.

 

I use Castrol or Mobil one.

 

The manual recomends 10w-30 for all but the COLDEST climates (5w-20 for say Nome Alaska in winter) and nothing heaver than 30w - I started w/ 20-50 after my rebuild but have since changed to 10w-30 because of excessive oil pressure - the guage would be pegged at 120psi by 3000rpm even when hot. Now after warmup I get 60-80 psi at 3000rpm and actually loose less oil through my leaky turbos (due to the reduced pressure I believe)

 

I use 20-50 Castrol GTX I replace it every 4 months thats less than 150 miles on the FD.I figured its over kill but I will insure the motor only gets fresh oil and a new puroilater filter.Dosent make sense to use synthetic if you replace youre oil sooner than 3K, plus the 13BREW will not last any longer you have a better chance of failer from o-rings.I would worry more about better cooling that type of oil?

 

You are wasting your money.. spend a little more on a better oil and filter. There is no reason to change your oil that often unless you live in Hazard and drive on dirt roads all day.. it is just overkill IMO.

Matt
93 SSM

 

Im using Castrol GTx right now.. can i just switch to Moble 1 syn? is that gon be a problem?
Its also getting warm in here... so i should use 20W 50.. correct?

Thanks

 

Yes, you can just switch. I don't know how the rumour started that mixing mineral with synthetic is harmful. The oil companies even sell mixed blends. BTW, I believe Mobil 1 comes in 5w-50. The advantages of a full synthetic.

 

Ive heard that synthetic doesnt work well when its mixed with fuel like in the rotarys, so the apex dont get their protection against the rotorhouse. Have you that use synthetic notised any more rotorhouse-damage?

 

Hey Max...

Why do you say "Stay away from 10w 40"?

What's wrong with this weight?

I stay away from Castrol myself... It was fouling plugs
every few months...

jc.

 

Conventional (mineral) 10W-40 oils have more viscosity enhancers in them, and this has given them the reputation of not performing as well as other weights. No car manufacturer that I know of recommends this weight for any of their new cars, which might also be an indication that it isn't good oil. As with most information available about oils, this is more of a rumor than a substantiated fact.

-Max

 

Im about to change oil and CAN'T DECIDE!!!!

Moble 1 or my good ole GTX??!!!

AHHHHHHHHHHHHH

 

I'll decide for you.....GTX.

 

Why dont you try an inbetween oil like VR-1 Valvoline 20w-50. In texas I HAVE to use that. Nothing but good things from valvoline. Mobil 1 if I go synthetic.

 

gzon -

In Sweden do they sell 10w-30? In Denmark they do not or haven't found it yet. We have Mobil 1 synthetic 5w-50. (4 ltr. - $72.00) no thanks.......... now they have Mobil 1 tri-synthetic 0w-40 for the low price of (4 ltr. - $85.00) for now, I am using Mobil 1 10w-40 (4 ltr. - $24.00) unfortunately, I only drive around 1000 miles a year and change the oil yearly as well. What are you paying in Sweden for oil? Just wondering........

 

The "don't use 10W-40" rule might not apply to synthetic oils.

-Max

 

valvoline or havoline is better?

 

I use regular mobil 10w-30.

 

hello Max -
The Mobil 1 10w-40 I use here is not synthetic. I might not have stated that clearly. The other two I posted are synthetic (5w-50 - ow-40) The only synthetic 10w-40 I have seen was Royal Purple from Racing Beat - and to think I used to live 20 minutes from Racing Beat.

 

im using castrol syntec blend right now and will probably go with full syntec when i get my car back up. . . im changing the fpd and decided to revamp my fuel system. anyways, i steer away from mobil 1 oils because i believe they are mixed with teflon. i dont think teflon burns very well . . . ya know. hehe. i know royal purple and amsoil are good, but they are too expensive for the importance of oil change frequency for an rx-7. i just like syntec. . . if anybody can tell me why i shouldnt use it then let me know. another thing about teflon . . . im in army aviation and i have seen what old teflon does. its pretty hard stuff. it is used like a bearing on the rear stabilator on apaches. itll chip up an what not. the particles of teflon in mobil 1 are more than likely tiny as hell so that wouldnt really be a problem. . . but what if those tiny molecules of teflon build up on your vital areas. i may be too cautious or maybe even wrong about mobil 1 using teflon, but i dont think that all that is very good if the do use it. ill check up on that. . . the teflon usage.

 

Aren't all Mobil 1 oils using the Tri-Synthetic formula? That's what I use. I get a box of 6 10w-30 Mobile 1's for 28 bucks.

 

Well. Im alergic to the mobil 1. My friend used it in his 323 GTR, and his valvelifters was making noise all the time cause of the low oilpressure it caused.
the GTX3 is 35 $ per 4L here, in my other cars I use Q8/OK 10W40 full synthetic and that I bought for 4$/litre. I reasenly bought castrol super plus 15W40 for my 323 GT and paid 2.5$/litre.

I think I will go for the castrol GTX 2, but then I have to buy a whole set, I will check out price today.

 

Martin - thanks for the prices. Magnus also talked about the GTX3.

 

what in the world is gtx3?