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?

 

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

 

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

 

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.

 

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.

 

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.

 

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)

 

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.

 

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.

 

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

 

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

http://www.bobistheoilguy.com/

 

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

 

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.

 

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.