bbullsj

i have an 83 rx7 limited edition. i read in my owners manual that the engine take just normal 5-30 or 10-30. i was wondering if i could use a synthetic oil or not. i also read that for the transmission to use API Service GL-4 or GL-5 and for the rear diff API Service GL-4. what are API Service GL-4 and GL-5?

Kentetsu

My own personal choices:

Engine oil: Castrol 20/50 with about 1/2 quart of Lucas Heavy Duty Oil Stabilizer
Manual Tranny: 50/50 mix of standard gear lube and automatic tranny fluid
Rear end: Royal Purple, with an extra tube of limited slip addative

axle

synthetics don't burn properly I also use castrol 20/50 best for older motors of any type and the 50/50 mix for the tranny remember rotaries burn a little oil by design and synthetics aren't made for this check the faq page it explains this

bliffle

Synthetics burn just fine. In fact, synthetics leave less ash than dino oil.

I use the OEM recommended weight of oil 10W-30 because I can think of no reason to use another weight, and I can think of reasons not to.

I use a high quality transmission lube, Redline MTF, because it improves shifting noticeably, and it provides a more durable oil film when the car is stored.

I also use Redline LSD gear lube in the differential.

Many of us use a fuel additive to supplement combustion chamber lubrication and to keep the fuel system clean. Marvel Mystery Oil and 2-cycle oil both seem to work good.

PercentSevenC

I've been using 10W-40, but I'll probably switch to 5W-30 non-synthetic (only because I can't afford to buy 0W-30 synthetic all the time :P) when I run out of my current supply, because my oil stays pretty cool. Engines with beehive oil coolers tend to run higher oil temps.

Fatman513

Engine: Castrol GTX 10w-40
Tranny and Rear diff: Royal Purple 75w-90

I'm gonna give the MMO a try on my next fill up.

FirebirdSlayer666

iTrader: (3)

I would not recommend using anything lighter than a 10w-30 oil. I use Pennzoil 20w-50. API Service GL-4 and GL-5 are different grade gear lubricants. You can use anything from 80w-90 to 75w-140. This reminds me that I have to check my trans and rear end fluid in my SA, I haven't since I got it(I know I'm bad LOL)

PercentSevenC

I don't know whether you are referring to my post, but I assume you are, since oils lighter than 30 weight aren't very common. Lest the misunderstanding be perpetuated, 0W-30 is not lighter than 10W-30 under operating conditions. All are 30 weight oils and have the same viscosity when warm, but when cold, 0W-30 is much closer to its operating viscosity than 10W-30 is. This means less wear on startup (which is when most engine wear occurs).

Simply put, there's no reason why you shouldn't use 5W-30 instead of 10W-30, and plenty of reasons why you should. 0W-30 is even better, but is only available as a synthetic, and is thus considerably more expensive.

cpa7man

iTrader: (2)

GL-4 lubricant is better suited to the tranny where high sheer forces are not a problem. The GL-5 lube is too slipery for the syncros and can cause premature syncro wear. My advice use Amsoil MT (GL-4) or Red line MT in the tranny and a GL-5 75-90WT in the rear end.

Seems to me our motors are not very hard on oil, if you change it often I don't think it matters what you use. In high stress applications such as racing use a synthetic as stated above.

rearviewmirror

Read this regarding oil weight... http://www.ferrarichat.com/forum/faq...=haas_articles

Fatman513

The Ultimate "everything you wanted to know about oil" website:

http://www.bobistheoilguy.com/

vipernicus42

iTrader: (4)

My choices:

10w30, whatever brand my parts store has cheapest in non-synth (the frequency of oil changes and which filter you use are much more important in my mind)

RedLine MT-90 in the transmission, since you only do it once in a blue moon you might as well use the GOOD stuff

Since I don't have a Limited Slip Diff, I just use a Synthetic 75w90 Gear Oil, again whichever brand my parts store has available.

Jon

rx7learner

Wow.... I was just thinking... not another oil thread...

BUT then I started reading that ferrari link that you put up rearviewmirror and it really clears up much of the oil confusion.

Now... I can try to find what weight will give me a 10psi raise in pressure for every 1k in RPM increase.

AND

I know that its flow... not necessarily pressure thats key to the effectiveness of the lubrication.

Im 3/4 finished reading it...

Thanks.

Rogue_Wulff

I don't agree. Many cheaper brands do not have the additive packages found in the higher quality lubricants. In the end, you get what you pay for.

Personally, I use an oil that is approved for use in airplane engines. In everything I own. If it's good enough for FAA and US Military approval, it's good enough for me. One benefit to this oil, it is designed in a way that any carbon left after it burns will be soft and flakey, not hard as a rock. An added bonus for a Rotary, since carbon deposits can kill them quickly.
I do use synthetic lube in both the trans and diff. The synthetic I use has the LSD additives in it, so it's safe for use in my LSD.