So yeah..., I'm going to do a full oil swap some time next month, and I've been reading around about the oils.

I'm looking to get my car into the best shape possible (I never settle for cheap crap when it comes to the car). Any recommendations?

I need:
-Engine Oil
-Transmission Oil
-Limited Slip Differential Oil

 

RP Engine Oil
Redline Trans and Diff Fluid

 

Agreed, thats what I use.

 

I use Royal Purple for Everything. 5w30 engine, MaxGear 75w90 for Trans/Diff.

 

Question: Is Royal Purple synthetic? As much as I want the best for my car, I really don't want to go beyond "the book".

I read around, and the Royal Purple logo says "Synthetic Oil".

Also, is the Royal Purple XPR Racing Oil any different from the normal ones? I don't use methanol, nitrous, etc. etc., which the product description seems to suggest that the XPR is best for.

 

Racing oils are designed for the track, not city traffic, I read somewhere that they are too thin.

 

^^ they have different additive packs for totally different usages.......

Has nothing to do with viscosity...but more about how well they stand up to crap around town driving conditions.

 

Okay, a little change in my question:

What's the best NON-SYNTHETIC engine oil money can buy?

 

The lines become blurred. The more you refine petroleum, the more you approach and then exceed the definition of "synthetic". Unless you're talking about "building" oil molecules out of individual carbon and hydrogen atoms with nanotech, all of the processes start out with some kind of hydrocarbon feedstock. Some of the fancier ones start out with natural gas, iirc..

You've got the right forum, some searching will give you hours of reading if you're inclined. If you really want to go off the deep end about oil, visit "bobistheoilguy.com". Have fun!

 

Huh what? Best oil money can buy ?

I use Mazola for cooking, Betorili (Spelling) for salad, and maybe some peanut oil for frying.

j/k :P

Well, any name brand oil should do, Synthetic or not. I will stay away from crap like *Autozone blah blah blah* tho. Yeah they're name brand, but not some name brand that I can trust. They're selling them for like 1.25 a quart O_O

True Synthetic should use Group IV or V Base stock. Royal Purple use IV, and Redline use V. Some Synthetics like Castrol Syntec, are NOT true Synthetic, most of them are Group III Hydrocracked oil like Pennzoil. The ONLY "true" Full Synthetic in Castrol Syntec is the 0w30 one.

Castrol GTX is a pretty famouse non-synthetic oil that a lot of people use. but I would suggest to stay away from the 5w20. get at least something with 30 grade. Synthetic or not.

I have been using nothing but Synthetic for a long time. Yeah I got some *not real Synthetic* from Castrol, but I never use it on my car, I used them on my bro and father's car LOL, but I still mix them with some True Synthetic like RP and 0w30 Syntec. Im using the Syntec 0w30 right now. when my stock runs out (maybe another 5 oil change), then Im gonna start using Redline 5w40.

 

CASTROL GTX

 

Having tried many different gear lubes, I always find myself coming back to the factory-type 75-90, usually Mobil1 synthetic. I have had trouble, even in the summer, with the "clinging-type" oils making my tranny synchros slow to spin up. The same phenom resulted in a stiff rear diff when I used RP. Engine oil? I am looking into some new stuff right now.

 

Thanks for the info.

But why stay away from 5w20 when the manual says explicitly to use 5w20?

 

Because 5-20 was spec'd so as to meet CAFE standards. I use 0-30 in the winter, 5-30 in the spring/fall, and 10-30 in the summer.

 

some people believe its too thin. i was running 10w-30 for a while and i didnt really notice a difference. some people even recommend 10w40.

since my dealerships change my oil i get 5w-20. also, i use nothing but castrol gtx. once my warranty runs out i'll be using a synthetic, probably 10w30 or 10w40. very important to let the engine properly warm up before you move the car if you go to a higher weight.

 

+1 for Castrol GTX

5w20 is the one Mazda officially wants us to use so it meets CAFE. Supposedly it gives better fuel economy (but at what expense?!?!?) and is also given to other Ford vehicles in the US.

Other regions of the world recommend much heavier weight oils for the RX-8 (including 40W). 5W-30 has been used by lots of folks here and is the one to go for IMO.

The 5W-20 factory fill is only good for one thing... break-in and drain hahaha.. I drained it the 2nd day I got mine

 

Is there a well documented source that recommends 5w30? Seriously. This vehicle is my everything. If using the wrong oil leads to it going bust, I'll be SOL.

 

Mazda told the rest of the world to use 30 weight oil, is that well document for you ?

and MOST rotary expert recommend heavier than 30, not sure if that counts.

Like I said above, if u ask me I'll tell u to go with at least 30, for me, I will go 40 as soon as my supply runs out.

 

So what do you use right now for Gear box and Rear Diff ?

I kinda want to try Redline 75w90NS for the tranny and the 75w90 for rear diff

 

nycgps, how many miles have you driven with 5w30?

 

about 33K miles.

Just think of it, the rest of the world never got any engine recall, only North America did, and we're the only one thats spec to use 5w20. Does that tell you something ?

 

Woa before you go and destroy your tranny, don't put that 75W90NS in there!

You should be using Redline MT90 / MTL.. personally I prefer a 50/50 mix of MT90 and MTL (MTL is too light and MT90 is a tad bit heavy for cold starts.. and the mix works.. they're designed to be mixed for an ideal application anyway).

Redline 75W90 for the rear diff is correct.

 

Dude, allot of folks here love their 8s too. In my case, 4 years of anticipation, including immigrating to the US just to land a job, and having a strict savings regimen specifically to buy an 8 and keep it for life. 5W30 works.. really.

 

why wont the NS stuff works in the tranny ? it does not contain the slippy stuff for differential. Better for Syncro isnt it ?

I just changed my gear oil yesterday with RP 75w90. For the Rear Diff, well, I dont have enough RP that time, so I put about a quart of 75w90 in there, then the rest is Mobil 1 75w90.

I thought about MT90 and MTL, and I want to try something different. Im gonna play with my new coilover settings tomorrow and will jack the car up most of the time, hmm I might as well just drain the RP tranny stuff and try some Redline MTL + MT90 sucker

 

IIRC, our tranny calls for GL4 spec oil. GL5 (which 75W90NS is) will not work.