anybody can give me some advice on the idemitsu rotary-speific synthetic? i read it in rx-tuner, available in july. i'm a proud new owner of an FD ('93) she has a new rebuilt motor ~1300 miles, w/ a bonez downpipe. i'm going to keep her stock/original barring any other reliability mods. owner's manual calls for 10W-30. anybody usese idemitu's 10W-30? recommend it? should i switch to this or go w/ mineral? what brand/kind of oil do you guys use?

 

Nothing but marketing to get your money. Use any good synthetic like Mobil 1 or Motul. Do a search and you'll find tons of threads on the subject.

 

haha, I did a search for idemitsu and this is the only one that came up, I also am curious what their prices are n all...

 

< i use castrol, friends use : mobil 1 , amsoil

 

i use castrol 20w50

 

Redline 20w50 rules all........

 

My stock twins lasted 125,000 miles (and actually their seals and bearings are still fine; the primary's center housing cracked) and my original motor blew an apex seal at 98,000 miles. Car has never had synthetic in it and I continue to use Castrol 10w-30 and change it every 3,000 miles. I average 15,000 or so miles a year and race constantly.

I see no need for the added expense of synthetic oil in these cars as their engine life is related to coolant and apex seals, not oil. You can't use the life advantage of synthetic either because the oil in a rotary tends to dillute with fuel over time. The real advantage to synthetics are their useful life. If you have to change oil constantly anyway I don't see the need to spend the money on synthetic when the next engine will still die from puking coolant or an apex seal...

I do use synthetics in the tranny and diff though.

 

yes castrol 20w-50 is a good way to go

 

Valvoline VR1 20W50.......Florida weather.

ALI

 

Dino oil beads up and has an affinity for itself at high temps.

Redline doesn't

Redline has a higher film strength.

For example, their 5s30 is higher than the best dino oil at 10w40.

 

I agree with DamonB. Of the ~15 motors I've built, I've yet to come across one that died due to an oil failure, or had signs of any oil problems. Bearings were fine, etc. Rotaries just aren't as hard on the oil as piston engines are - bearings on a piston engine are under a LOT of stress, whereas a rotary the parts are just spinning - no hammering loads.

I use Castrol GTX 20w50 - it's cheap and you can get it anywhere. Change it every 3000 miles, and you're just fine.

Dale

 

Redline and some synthetics are suppose to have a little less Cd.

That equates to a little more HP.

A couple years ago I paid redline oil's site a visit. They did some dyno tests on a Vette and memory serves me right it showed that it added 5 - 10RWHP over Dino oil.

 

I don't doubt it but that's an awful lot of money to pay over the life of the car for just a few horsepower...

ps Cd is a derived aero coefficient, not a "slipperiness" term.

coefficient of drag= the ratio of the drag on a body moving through air to the product of the velocity and the surface area of the body

 

Ur intelligent to know what I mean.

 

Well, not to prolong yet another debate on motor oils, but I disagree. If anything, the rotary is harder on engine oil than a piston engine, mostly due to its high heat output. Bearing loads do very little to break down an oil; heat, shearing loads (the stationary/rotor ring gear mesh), and fuel dilution will.

While the cost/benefit debate will rage on, I for one would rather use a good synthetic due to its friction reduction and grade quality.

 

I don't argue for a moment that synthetic isn't a better product but for me I don't feel the return for my much higher investment in synthetic oil pays off economically.

The rotor bearings and stationery gears on these engines have no real wear problems except in extreme applications and the journals on the eccentric and the rotor bearings are very generous compared to a piston motor. IMO rotary engines really are not any harder on oil except for the fact that they dillute it (and that will happen with no matter what you put in the pan), especially when you consider the rotors are only turning at 1/3 of the engine speed.

 

I used to change my Redline 20w50 in my FD every 10,000 miles.

No ill effects. It was on it's original engine that manage to hit 250,000 miles before finally dying.

With the FD, I did the same. Every 10,000 miles no ill-effect. I must admit that by the time I changed the oil it was really dirty and must have diluted from a 20w50 to something closer to a 5w30.

Never lost an engine due to oil failing.

However, I've dropped that down to change intervals of 5,000 miles.

 

It's not that there are any "wear problems" with the stationary/rotor ring gears, or any other moving parts that are lubricated with the engine oil; if there were, I doubt that just using synthetic oil would solve such a problem. I stated that the shearing action of the gears breaks down the oil, because they aren't made for that type of abuse. And again, the journal loads and clearances really have no major effects on oil breakdown. You didn't address the heat aspect of the rotary. Its engine oil has much more exposure to higher temps (due to the total surface area of the rotor face being exposed to the combustion flame front, and there is no other real way for the rotors to get rid of that heat than by transfer to the oil, hence the need for oil cooler upgrades when tracking the car).

Nonetheless, as I said before, the cost/benefit debate can rage on endlessly, and there are so many good points (both objective and subjective) on both sides that belaboring this subject is pretty "pointless" IMO.

 

If we could just spend somebody else's money on upkeep of our cars we'd never have to worry about such things