rotarhead

Just switched to synthetic mobil 1 15w 50 which has resulted in a better idling smoother running fd with increased oil pressure. I highly recommend the switch. Researched thoroughly before going through with it. Mobil 1 and other synthetics provide much more cushioning or protection for moving parts, less residue or ash from burn of than dino oil, and of course higher temps before breakdown. I do not race and rarely autocross but I think the extra protection is worth it. Another big plus I forgot to mention is the thinner your oil is the easier it can move through all your engine parts lines ect...which means lower operating temps. The site that infuenced my decision the most was: www.vtr.org/maintain/oil-overview.html

Cap'nWankel

Always wondered about the rumored synthetic issues. heard it doesn't burn as well. Any problems yet?

Cap'nWankel

with rotarys that is. I know the stuff works great with pist-ons. Nice choice w/ the Mobil 1 by the way. Thats the only way to go, if you do choose synthetic

Rotaree

It is said that Mazda branded all synthetics as non-compatible with their rotary engine because of one manufacturer in particular, during some research performed by Mazda, that did not perform well with the rotary. This is not to say, however, that all synthetics are not compatible with the rotary. It is trure that the synthetics do not burn quite as clean as the fossil form, especially since the rotary purposefully burns a small amount to lubricate and cool the seals on the rotors. Some problems with catalytic convertors clogging up are the only cons I have heard of to using synthetic oil in a rotary. I would much rather replace my convertor every 15,000 miles and have the extra protection the synthetic provides than not to have that protection. Many race teams and independent car owners have successfully used synthetics for many miles with no problems excpet the afore mentioned. Just a thought.

Falcon

You might want to consider Valvoline VR1 20-50 wt, its organic and burns better. If you change your oil every 2k miles it will hold up and doesn't have a chance to break down. Just a thought......

Happy Holidays,
André

JspecFD

iTrader: (2)

What proof do you have to corroborate this statement? Everything I've seen points to it being inferior in *EVERY* way to Mobil 1 at the same wt and it doesn't even come close to burning cleanly.

Falcon

Proof??

I don't have anything, like a report that says "its the best" but I know that "syn" oils don't burn well adding to rotor carbon. So all I did was suggest it, and by the way thats what Pettit suggest also, didn't mean to change your mind. Syn oils are great, hold up to higher temperatures, thats what I ran in my C5 Corvette, but if you change your oil every 2k do you think you have the breakdown problem. Only a thought.......

Happy Holidays,
André

rotarhead

Thanks for your comments but please read the site that I referred to and do not go by who said what there are some others I have read that were very helpful I will see if I can find them. Everything I have read says that
good synthetics burn very clean (like almost 0% residue or ash left behind) no dino oil can compare so stop worrying about clugging up this and that. Not just a thought but scientific research.

Falcon

Just a thought to you, I had a racing 2 stroke jet ski, and I ran Torko R50 because it had a flash point of 525 degrees, almost as high as bean oil with 530 degrees. It left a subsatntial amount of residue in the triple pipes. The uniqueness about synthetics is their ability to handle high heat loads and retain their viscosity and lubrication. I am not trying to change your mind, but the essence of syn oils is not to breakdown and burn. Use as you wish and take care.

Take Care,
André

dis1

Arg... another oil debate. Well I just switched and couldn't tell a difference. Sometimes I wonder if synthetics are working like placeboes on some people Anyway the link you listed doesn't seem to be working but here is one I often list to support some of my views. It suggests to me that synthetics and dino oils have similar ash content and although the flash points of synthetics are higher they will all burn. http://www.vtr.org/maintain/oil-overview.html Also before somebody makes themselves look stupid by telling me to go read my own link because many of the synthetics have 0% ash, "---" means the data wasn't obtained. I have also never seen any conclusive evidence one way or the other as to the benefits or destructive powers of synthetic oils. I have even seen comparison tests in piston engines where different oils were used in a fleet of taxis over thousands and thousands of miles and no noticeable difference was observed when the motors were torn down. I would suspect that a rotary engine would benefit even less from synthetics because there are fewer moving parts. The only part I would be particularly worried about are the apex seals and since regular oil will protect them just as well as synthetic oil I'm wondering if there is any benefit at all. I say this because the seals sort of hydro plane on the oil film and there are only two conditions where they don't. One is at start up, where no oil is there regardless of type and under sudden vacuum where the OMPs are sucked dry or something to the effect. People cite smother idles and lower temps but for the life of me I can't see how an oil could produce lower temps. Less friction sure but where? The shaft? The turbo bearings? Or maybe better heat transfer at the oil cooler? Unless somebody can give me a solid theory as to why I'm not going to believe a hand full of people when I personally didn't notice any difference. Lastly I submit the following forward, which I have listed before. It suggests to me that the entire "unclean burning synthetic oil" thing might well have been a nasty rumor that became gospel.


After many years of discussion on this topic, I finally ran across
something from a manufacturer that addresses the history of the
issue directly.

My source was, believe it or not, a wall in the office at Sun Auto--a
junk yard specializing in 1st and 2nd gen RX-7s. It is in the form of
a letter written on Amsoil letterhead, and signed by someone in the
Technical Services Department. The letter was written to a private
individual, but it looks like a form letter, and I saw it in a public
place, so there should be no harm in paraphrasing it here. I am
working from a copy.

The letter says the reason Mazda did not recommend synthetic
oils was due to problems with the rotor seals (part numbers 0820-
11-341 and 1202-11-343). The problems were apparent with "at
least one" synthetic oil.

Amsoil had been sponsoring RX-7 racing since the '70's, and thus
had always been concerned with this.

When Mazda came out with their caution in 1988, Amsoil tested
for seal compatibility.

The letter implies that the seals in question were designed to swell
as a means of replacing worn material and maintaining component
integrety. The idea was to control this swelling within an
acceptable range, which Mazda specified as being between ten
and twenty percent.

Amsoil used Pennzoil 10-30 as a reference and measured an 18.5
percent swell rate. Several Amsoil multi-weights were tested and
found to range in "swell rate" between 14.5 and 17.3 percent.

The following line is a direct quote:

"Since that time, Mazda has rescinded their recommendation not
to use synthetic oil in the Rotary engine."

End of paraphrase.

Now, this letter is dated September of 2000, and the notion that
Mazda didn't caution against using synthetics until 1988 was
enough to send me scurrying to the owner's manual for my 1985
GSL-SE. No mention of synthoil there--nor in the shop manual.
The only requirement is an SD, SE, or SF oil.

The last line--that Mazda had recinded their anti-synthoil stance--
was also a shocker. I would have assumed any information like
that would have hit this list like a clap of thunder. Of course, I am
in no position to confirm the assertion, or to argue with it.

Nothing above is going to change anyone's mind about the issue,
but it does tend to reinforce some of the points made in past
discussions, and to put things in historical perspective.

If anyone has a direct source to verify the notion that Mazda
currently has no prohibition against using synthetics, I would like to
know about it. Last time I saw a Mazda reman in a crate, I
THOUGHT I saw a tag on it with a warning that using synthoil
would void the warranty. (Note: these engine seem to have about a
dozen tags tied on them when delivered. You'd think someone
would save time and energy by supplying a detailed instruction
sheet instead.)

And, of course, there are no rotary cars currently in the United
States with original engines still under warranty, so the point is
moot from that perspective. We'll have to see what happens when
the new rotary cars hit the showrooms.

Best wishes,
David Lane
'85 GSL-SE (CarTech turbo)
Info on the car at:
http://www.wankel.net/DavidLane/

Rotaree

[Quote]And, of course, there are no rotary cars currently in the United
States with original engines still under warranty, so the point is
moot from that perspective. We'll have to see what happens when
the new rotary cars hit the showrooms.


There are companies that warranty the rotary engine...just not original factory warranties (i.e. extended automotive warranties). Would be interesting to see if they prohibit the use of synthetic oil in them...actually...they probably wouldn't know what a rotary is much less care about the oil used in them.

juliof

If you change youre oil every 2k or less mineral based oil will not be in youre motor long enough to really be stressed and heated enough to really break down any ways? And with the 13BREW infrequently lasting past 100K synthetic oil is not going to extend engine life, I havent read about any one rebuilding a motor because it failed from using mineral based oils, sythetics are better but I dont think so in this application.

machinehead

Well, I just had my engine rebuilt about 2,000 miles ago. I am running Royal Purple synthetic... I will be sure and post any misshaps. So far so good.
I did read something interesting though. On thier website they recomend with piston engines that you break in your engine with regular oil then change to Royal Purple afterwards. They said if you don't the rings may not seat correctly. I was wondering if this could also apply to apex seals?

Falcon

opps.......I guess I stepped into it

Perhaps Mobil and Valvoline etc. would like to sponsor some of us in a long term test. Providing free oil and filter changes for the life of our cars including a meticulous teardown and rebuild, solving the debate.

If anyone has connections with oil exec's, I would like to be the first to volunteer. All these parts are adding up and I could use a break somewhere!

Just Dreaming........

skunks

I use to have a problem changing my oil cuz my car is dropped about 2 inches in the front and has a body kit and it would take me about an hour to get my car up on jacks with out scratching anything. I currently solved that problem and am gonna switch out my oil about every 1 to 2 weeks. im gonna stay with mineral cuz its about 5 times cheaper then the synthetics but even though i know that synthetics are less prone to break down but to quote Falcon, "if you change your oil every 2k do you think you have the breakdown problem." and i highly doubt that i will if i change it that often, thats just me.

rotarhead

I believe lower engine temps come from having a less dense fluid (not as thick as dino) which causes less resistance (less friction less heat) between the moving parts and better faster circulation also reduces heat as the oil moves through the engine and the lines. I was changing oil every 2500 to 3000 before and the oil was pretty dark. I do drive hard at least 3 times a week for an hour at time. I am curious to see how the synthetic will compare in appearance on my next change. Also in regard to heat less break down would mean more cushioning therefore less friction.

dis1

This is what people keep saying but again I ask: what parts are you talking about? Where is there less friction between moving parts? There aren't that many to make that much friction. As for faster moving fluid I also don't see how that can lower engine temps. For that matter I'm not even sure the density is different between dino/synthetic. I would think that the viscosity would make more of a difference here and that is based on the oil's rating, not if it's dino or synthetic.

maxpesce

15w-50 Mobil 1 has exactally the same high temp viscosity as 20w-50 conventional oil. Mazda's recomendation for the 13b-rew (per the factory manual) is 10w-30(much thinner than 20w-50) for all but the coldest climates (5w-20 below 0c).
Because the oil in a rotary needs to be changed at 3000mi or less due to combustion product contamination and NOT thermal breakdown you loose the MAJOR advantage of synthetics - LONGER LIFE - My 93 is my daily driver and I can't afford to be spending $2/qt extra for Mobil-1 (vs GTX) when I am changing oil on a monthly basis ( yes I was driving my fd 2000+ miles/ month I now car pool though)

rotarhead

Two rotars are spinning at incredible speeds with gears at there center turning a shaft and
all that spinning causes lots of friction and heat. That same oil thats protecting those gears is also circulated through the turbos and oil cooler (which is probably the best upgrade to reduce heat) and the quicker it can move the cooler its feet can stay while running around doing its job.

DamonB

Actually the speeds aren't that incredible. Remember the eccentric shaft turns at 3X the rpm of the rotors due to the stationery gearing. So at the 9,000 rpm redline the rotors are humming along at 3000 rpm; hardly incredible compared to modern small displacement piston motors.

That said; my two cents is that oil cooling is very important on a rotary and using a good dino oil and changing every 2,500-3,000 can't leave any advantages to synthetics. Again, synthetics primary attribute is long life; not "better" lubrication. The info on ash could be very relevant, but I have seen no definitive answer.

And as we all know your turbo rotary will more than likely require rebuild due to coolant o-ring failure way before any mechanical wear problems crop up. I have never heard of any longer life due to oil in a rotary, namely because they don't last as long as a piston motor. Fact of life. I am not rotary bashing at all; I love the motor. But if I had to build a simple, bullet proof million mile motor I would build a big, torquey piston engine.

rotarhead

3000 or 9000 whatever there are parts moving really fast causing the oil to get hot and break down. I think my oil has been equally messed up looking if changed at 2000 or 5000. anyway the only oil protecting the 3000 rpm spinning rotors is from the oil metering lines. I am referring to the shaft that is spinning at 9000 rpms and the friction generated from the gears at the center of the rotors. My real test will be when I do my
next change and if the oil is clear or not. I smell what your stepping in when it comes to
whats ruining are engines but heat is also a contributing factor and if we can reduce it should help extend engine life. Better oil less friction less heat.

juliof

The best upgrade to minimize oil break from heat would be to add a second oil cooler, or go with a larger set of oil coolers and install a larger rad to keep engine temps down.If you change oil every 2k or less like I do, youre motor will only see clean oil which is better than replacing worn dirty synthetic every 3k.The truth is what type of oil you use is the least of youre problems with the FD motor.