Full synthetic motor oil or no?
 

Hey guys just seeing if you guys think I should run a full synthetic motor oil in my FD or just conventional.

use whichever type of oil you wish. it's up to you.

keep the cows at College!..please!
Diabolical1's Advice is about the best advice you can get really as it is a highly debated subject that Guys have varying opinions on.Six of one and half a dozen of the other.
You can use whatever you want or wait for a "real answer"..when the "cows come home"..!!

What I did was, I went w/ Idemitsu Racing Engine Oil 10W-30 from
MAZDATRIX for Mazda RX7, RX8, Rotary Engine Parts and Accessories

boom....there is a "real answer"... use specially designed oil =)

- Bob is the Oil Guy

Has got to be the best site for engine oil related questions. No doubt.

Boom? Not hardly. :rolleyes:
To the OP....
diabolical and misterstyx are right. Make your own choice... there are good arguments for both sides.
Stock or mildly modded, well cared-for street-driven FD's rarely have oil related failures. In fact the majority will require coolant seal replacements before anything else. It's the price of forced induction.
ALL rotaries tend toward oil contamination and some fuel dilution. They also leave a significant amount of oil stranded in the rotors and oil cooler(s) during changes. What that means is that oil change intervals should be a little closer than most piston engines. And what that means is using higher priced (synthetic..and especially magic rotary oil like Indemetsu) is going to cost you alot more. You could argue that putting that money away for the inevitable coolant seal replacement makes more sense. Added into this is the fact that a working OMP injects a small amount of oil into the combustion chamber. Synthetics tend not to burn as cleanly as conventional oils. IIRC, those are most of the major arguments for conventional oil...but there might be more.
The argument for synthetic is that high temperature peformance of synthetic oil is far superior to convential oil. Your turbos are a high temperature enviroment. Carbon build up is common for ALL rotary engines, regardless of the type of oil. Synthetic formulations have also improved over the years (in many synthetics, not just Indemetsu), so that carbon deposits aren't as much of a concern over that which you would see using conventional oil. And most FD owners don't use them as DD's, so mileage is lower and so are the number of required oil changes. That means they don't worry about spending at least a little more for synthetic. Additionally, many owners, like myself, have added inexpensive auxilary injection systems. These not only reduce carbon deposits, but assist in cooling both the IATs and and engine temperatures while lowering knock values.

Learn about your car, learn about the rotary and search in the 3rd Gen. section for oil related threads. Then decide for yourself.

Thanks guys for the advice

I'm learning what I can, but everywhere I look people seem to vary on this subject. Some make scary assertions on both sides, so it's hard to feel confident with my decision. I recently acquired an '87 turbo II with 25k miles on it, and my first oil change was a top-shelf synthetic, against the advisement of my owners manual (which I believe was accounting for the quality of synthetics 26 years ago). The guys who did the oil change & inspection for me seemed enthused and knowledgeable about the car, but it wasn't until I left that I saw the shop's oil sticker recommending a change in 10,000 miles. I am going to take it in sooner than that for sure, but how much sooner is something I'm uncertain about. I will try to find answers to these questions elsewhere, but I'd appreciate your input too.

1 - You mentioned coolant seal replacements as a problem for FDs. Are you familiar with any parallel/recurring issues in the FC?
2 - Pretend this Turbo II is yours for a second. What oil would you put in it (considering that the last change was synthetic), and how often would you get it changed if money was not an issue?

This car is driven daily, but doesn't necessarily qualify as a 'daily driver' as I am unemployed and do not have any substantial daily commutes.

I'm new here, so I apologize if these questions have been asked and answered a million times. This is my first post, I'm only beginning to comb through the depths of this forum.

there is no magic or mystique involved here. i will make two statements that may hint at contradiction, and while i will state them as opinions, neither of them are really conjecture.

1. tit for tat, synthetic oils are better than mineral-based oils. they are created to be better. period. there is a reason that break-in takes longer using a synthetic. :)

2. engine oil is engine oil! period. just as synthetic development has come a long way (including the combustion residue issue), the refinement processes for mineral oils have come a long way. oils are better than they used to be and they do a great job when used within reason. repeat ... when used within reason. :)

the key to oil changes is not a time or mileage interval so much as it is learning to read your oil when you check it. you should also become sensitive to using weights that are appropriate for YOUR car and the context of how you use it, not just whatever is "recommended." however, let me not digress.

where do i stand? i use both, depending on my situation at the time. as i said, the choice is yours on what to use, but until "we" can all have a discussion on oils of the here and now, AND not include the old arguments and old thinking, the choice will continue being much harder than it has to be.

Not off-hand. I've never owned a TII, but can guess that a turbo, but nature, increases combustion temperature/pressure. That will add stress over what you will see iwth an NA. That inferes that it would suffer similar issues...but maybe not quite to the degree of an FD. Regardless, cooling should be a bigger priority than what kiind of oil you use.
Every situation is different. But I use synthetic in my FD for reasons I outlined above. No worries. You're in the right section and that's why I tried to cover both sides..hopefully fairly. But know that once you move out of this section...say to the 3rd Gen. Section, you're expected to search. Asking this same question there would attract groans, grumbles and likely some flamage.

Yes

The standard oil change interval for your car is 5 months / 5,000 miles for normal driving conditions, or 3,000 miles / 3 months for unique driving conditions (dusty or salty environment, high-performance driving like autocrossing, extended idling like a police car or taxi, etc.). The synthetic will last longer, but it is difficult to know when that is unless you send it out for analysis, which will cost more than an oil change. Also, the typical oil consumption rate for your engine is 1 qt per 3,000 miles due to the engine's oil injection system. This is why most people use regular mineral oil and change it every 3,000 miles as opposed to adding a quart and driving out to 5,000 miles.

I see that Sgtblue answered, but I will also respond as an FC owner of 25 years... The FC does not tend to have this problem. At some point either the coolant seals, apex seals, or side seals will fail due to old age, but there is no telling which will fail first. The best way to keep the engine from blowing a seal is to rebuild it every 100,000 to 150,000 miles. Otherwise, just drive it until it blows up, then replace parts as necessary and hope that the apex or side seals do not damage the rotors or housings too much.

I would use synthetic engine oil for a race car, or for a street car driven in the dead of winter. I prefer the Group V base stock oils like Idemitsu and Red Line for maximum protection (racing), although the Group IV base stock oils like Royal Purple and Amsoil are nice and slick for extremely cold weather and they also work very well on the race track. It is my opinion that the Group III "synthetic" oils and blends are currently in a no-man's-land that should be avoided by sports car owners. If the car is not driven on the track or in the dead of winter, I would just use a good mineral oil like Castrol GTX. The factory service manual specifies the oil grades appropriate for outside air temperature.

I highly recommend synthetic oil in the FC manual transmission and differential, regardless of outside air temperature or the type of driving. The transmission is very notchy unless you use synthetic, and the longer drain interval of the transmission oil makes it more affordable. Mobil One has been known to eat synchros, but any other brand would work fine.

You can't accurately read oil unless you send it out for professional analysis. While there are some telltale signs that you can eyeball, no human being can look at oil and assess its viscosity and contamination level. This is why fleet vehicles and race cars use oil analysis to determine their oil change intervals.

Otherwise, I agree with everything that you wrote above.

Castrol gtx 20w50

What about idemitsu? Anyone running that?

^They must be selling it to someone. But it's still stupid expensive, before shipping, even if it is 'magic' rotary oil.

For my turbo based cars I have used 15w40 or a 20w50. I may be a bit of a snob as I run amzoil in my 950rwhp G8

I run Baby Oil in my 140 hp N/A..lol!

Yeah? I run Whateverisleftover brand 10w 30 in my 4 rwhp Honda mower. ;)

Is it safe to use synthetic oil on FD rx7 with e85 and pushing 500hp as a somewhat daily driver? Or should I just stick to castrol conventional ?

^Did you read the thread?

Safe? Yes

Better? Yes

Expensive? Yes

Necessary? No

Your choice.

As a Group IV (PAO) base stock oil, Amsoil is actually 2nd place on the snob totem pole. However, it is a very close second, and with modern technology many experts question whether Group V is any better than IV, and even some of the Group IIIs are pretty darn good. Below is a list by base stock if you want to be a real snob, although the brands are not in any particular order.

Group V - Red Line, Idemitsu, Motul
Group IV - Amsoil, Royal Purple
Group IV/III blend - Valvoline SynPower, Mobil 1
Group III - Amsoil XL, Rotella

Snobbery aside, I would suggest using whatever seems to run best in your highly-modified engine. ;)

that is a Great site with tons of good info.

Ya idemitsu is pretty expensive.

I've heard from some rotorheads that running synthetic is not good in a rotary engine because when it gets burned it leaves a chemical residue that can shorten the life of the apex seals. Can anyone confirm or deny?

Up until the 1980s, many brands of synthetic oil would not burn properly, and the residue caused striations on the rotor housings. Some of them would also cause problems with the seals of all types of engines, resulting in swelling, shrinking, or deterioration. Some brands throughout the world still have these problems, which will cause carbon buildup and oil seal deterioration in rotary engines.

Although Mazda recommends against using synthetic engine oil in their street cars, the Mazdaspeed Motorsports Development catalog does recommend synthetic engine oil to their race teams. This, combined with the price, is why I tend to recommend mineral oil for street driving and synthetic oil for racing.

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