Hey fellas,
I just got an 85 GSL-SE w/ 108k on the original engine. From what I can tell, it doesn't have any oil leaks, and the engine runs as strong as I could ask a stock engine to, but I'm still afraid to switch over to synthetic on account of the mileage. I've heard three brands for dino oil over and over - Castrol, Havoline, and Valvoline - but I don't know the slightest difference between them. Anyone had a particularly good (or bad) experience with any of them? Thanks guys

 

Been running 20w50 castrol in all the rx's i have owned and never had a problem. rx7doctor

 

castol 20-50 also. can't go wrong.

 

ditto

 

I think that most on here run the Castrol. I use Valvoline 20-50 high milage in my 85 SE.

 

I heard someone mention about how you should not use the high mileage oils in a rotary because of them making the seals swell up and possibly causing a problem. I cant remember if it was here or another forum but I am sure I heard it. Anyone else heard this also???

 

DO NOT go to synthetic. Just use good ole normal moter oil. Synthetic does not burn and will not work very well at all in a rotary engine.

 

I knew it.....could have called it before I even wrote it. Damn . Hey, I have been using the stuff for going on two years now, I haven't had any trouble! The only oil that anyone has ever blasted is synthetic.

 

wal mart oil works good

actually not, castrol 20w50 but the wal mart oil is good to have for back up oil in the car, plus its 80 cents a quart

 

I use quaker state peak performance 10W30. I've never had a problem with it in any engines I have put it in. All 4 of my families vehicles have it and not a single problem. I live in a cooler climate so I need an oil that is a little thiner. 20W50 is too thick for fall/winter use.

 

lol, i have supertech or whatever oil in my car right now I need to do an oil change

 

...and on the other end of the cost spectrum is VC oil. Its lubricating properties are the stuff of legends. The smallest amount completely eliminates friction from bearing surfaces. It exists, yet can't be found anymore. Don't even bother looking for it. Oh, by the way... VC = virgin crotch

 

^^ lmao ^^

I'm using Valvoline 20w50, but I guess when my case runs out I'll switch to Castrol.

 

I've used synthetics (Mobil 1 and Royal Purple) for 7 years in multiple engines upon the advice of Rob Golden at Pineapple Racing. He has used sythetics (Mobil 1) in all his vehicles for over 15 years and recommends them to all his customers. Racing Beat also recommend synthetics (previously Amsoil, now Royal Purple) to their customers. In fact, the only people who seem adamant that synthetics are bad are people who have no experience whatsoever. These parrots simply repeat the same bullshit as if it were fact, including the absurd claim that "synthetics are not engineered to burn" (and thus leave deposits). In my experience and those of people I trust (respected engine builders, etc.), synthetics leave fewer deposits and are far superior in reducing wear and resisting viscosity breakdown. Why Mazda continues to state synthetics will void the warrantee is a complete and utter mystery to everyone in the industry. Some think this is a legacy of an incident of twenty years ago relating to a single product and, for liability reasons, could not ban a particular brand by name...so they nixed them all. I don't know, but it makes little sense given all the advantages proven over all these years both on the track and the street. That said, nobody is recommending anyone switch a high-mileage engine to synthetics because, at that point, it's too late to take advantage of the benefits and there is a possibility that seals swollen from use of mineral oil could "un-swell" and cause leakage.

 

Mobil 1...10W-50......the "dangerous synthetic oil" thing is an urban myth, aka., as a lie...

 

...here we go again...

 

I have read both sided of the argument on synth VS. dino and it seems to me the only way to really work this out once and for all is if we stop talking about it and test it. It seems to me that if we get 2 large aluminum pans an subject it to a dino oil and the other to a Synth and hit them with a torch until they break down and then look at the deposits left, we could get a clear understanding on which is better. If the belief is that more additives cause deposits then no one based on that should run Castrol. I know that for a fact as they get there supply from the cheapest sources and then add a **** load of stabilizers to thier supply to make a very consistant oil ( I would think this would be better) but for the sake of this way too ongoing discussion and the vast statements that anything added to oil makes it not burn as well, then castrol would be the worst based on that.
I know that the pan Idea isnt the best of test environments but it should give a base line at the very minimum.

Let the flamage begin!

 

Just don't use bleach

 

Objective testing of something like this can be very arbitrary and overly simplistic, not providing useful information to those wanting to make an informed decision. Seriously, how do you model a test to simulate the temperatures, pressures, AFRs, gas flows, etc.? Objectively it can be proven that synthetic oil can withstand higher temperatures before breaking down. But, that doesn't tell you how well it "burns" in the combustion chamber. Nor would burning some oil samples replicate what's really happening in the chamber because of so many variables...how does it burn near the point of ionization? How does it burn near the apex seals? What if you advance or retard the timing, dramatically affecting "cylinder" pressure? AFR? Octane? Are unconsumed particles carried out in the exhaust stream or does it build up in the chambers?

In such a complicated scenario, the best tests are "real world", subjectively done over many, many years by top professionals in the field. Suprise...it's been done. Who better than an engine builder to tell you if synthetic oil leaves deposits, either in the crank case or in the chambers? Obviously, it stands up better everywhere excluding the chambers or Mazda wouldn't use it in their own race cars, like the Le Mans 24 Hour winning 787B and all those other championship race cars. Racing proves it's great stuff with significant advantages under the harshest conditions. But race cars don't typically lubricate apex seals using sump oil, so that's as far as that goes. So, the real question involves combustion inside the chambers. For that, any engine builder who has significant experience with synthetics in street cars can definitively tell you if there are excessive chamber deposits. Again, the only answer I have ever heard is "No; there are fewer deposits!" Personally, I don't care why there are fewer deposits; synthetic oil could be the "dirtiest" burning lubricant in the world but if it doesn't stick to the chamber and cause excessive build-up, who cares? The enemy are deposits and all I know is that synthetic oil causes fewer deposits according to my most trusted sources. I also know from personal experience that it ran great in all the vehicles I've used it in over the last seven or so years...can't tell you how the insides looked, because I have never in my life lost an engine. Draw your own conclusions.

For what it's worth, my latest daily driver uses Castrol GTX 10w30. Synthetics, for all the benefits, are still hard to justify economically and mineral oils are still very, very good lubricants if you change them often enough. But, in an engine I really care about, synthetics are usually my choice.

 

Thank you for that wordy explanation but you have yet to explain how heating two different oils past break down point and showing the residue left behind is any more or less accurate than your 15,000 variables that could change the test method. all you have really made clear is that Mazda for what ever reason doesnt use it in their race cars, which has nothing to do with me going to work. Also that all of the afformentioned variables, that only makes it imposible to establish a real base line any how. So it seems I am back to the pans as I will probably be dead and in the grave long before any "real world" testing could be completed. Anyone have a few frying pans that I can use :-) BTW I use Synthetic myself, Just because the only part I really care about is its ability to lubricate. If it burns nasty then let it. I bought a car with really crappy emissions in the first place.

 

Mazda DOES use synthetics in all their race cars, as I clearly stated. It's just not applicable to the issue of carbon buildup inside the chambers since they don't use sump injection. My point was that the issue of carbon buildup on street cars is very satisfactorily addressed by professional engine builders who most definitely see REDUCED carbon buildup. Burning the oil in a completely arbitrary fashion, not the least bit similar to the environment in the combustion chamber, will tell you exactly zero about real-world carbon buildup. As I said, it could burn "dirty" (not that I think it would) and still have no negative consequences in a real engine (as it most clearly does not). Why does arbitrary, oversimplified objective testing appeal to you more than subjective evaluation by professional engine builders for over 15 years? I'm not saying you shouldn't try it for fun, but I would have serious problems with any conclusions you might reach as they apply to the real world...even if they seemed to support my position.

Sorry for the quantity of words in my reply. In the future, I'll find some clever emoticon to "own" those I disagree with, thus avoiding any sustatative argument which might enlighten them. :P

 

My bad on that one. I was remembering that everyone has stated that they do not suggest the use in the street cars and I got lost in 5 other things I was doing at the time. So that is my fault.
The fact that you find the simplest test could never show any real answers is about break down and deposits shows your commitment to over complicating the facts. Say what you will but, it will at least show the oils at their break down point and what’s left in the pan. Each engine being different will produce different results. By eliminating the other variables, it gets you closer to the facts on the oil itself.

Its not a matter of (as you put it) "owning someone" But more a matter that even though you are right to some extent about what you are saying, you still can’t tell me that my method of testing wont get to the point of what oil leaves more deposit when its burned. I am still only talking about the oil itself. I’m sorry you take this so personally or feel that I am trying to argue with you because you feel that your somehow superior to me in your knowledge. I have spent over 4 years studying fluid dynamics. I understand that its still oversimplified but it was meant to provide a baseline for study on the actual break down on the oil itself . Not so much what it does in your engine as you will undoubtedly drive different and your car is set up different than mine or anyone else’s for that matter. I was simply trying to make a point about the oil itself. By discussing this, we are putting the thought process threw its paces. This is what it is all about. I am so sorry that you feel that this is a personal attack against your ego by my not falling for all of your extra noise. I am still waiting on how my test doesn’t provide a baseline on the oil itself and still would like to hear you view on that point and not you spending wasted time turning this into a pissing contest.

 

You are confusing my extra effort to be clear in my statements and support them as best I can with logic as being defensive or argumentative. I'm not taking anything personally but I can't control your perception, so take it how you will. I still don't think you will prove anything remotely relevant, but knock yourself out and let us know how it goes.

 

lol Very scientific. The only proof you need is the fact that engine builders who tear down and inspect these engines daily use and recommend synthetics. The only adverse effect is less money in their pockets due to longer intervals between rebuilds.

Just for the record... Mobil 1 all the way.

 

And to punctuate REVHED's excellent advice, think about this...how many here can say they have had their personal engine die because of the synthetic oil? All "I know a friend", "I heard from a reputable racer" and "I read it on a rotary website" answers DO NOT COUNT. That is exactly how an Urban Myth perpetuates itself. How many engines have YOU lost? YOU...<<<points finger viciously, stabbing at the eyes>>>...Here's my first person experience...It has saved my Rotary Performance 12A Streetport when I had the fuse holder for my electric fan literally melt away. All I had to push air through the radiator was car speed. Of course, this happened on the way home on I-20 in rush hour traffic, so car speed was only there for 40% of the drive home....the temp gauge was just short of the red zone for 10 miles but I got it home, radiator boiling and everything. I jumped a wire past the fuse holder to start the fan and ran water over the radiator until the needle was in the middle and shut it down. The next morning, she started right up and acted like nothing had ever happened. No smoke on start up and no smoke on the drive to work. That engine is still around waiting for the stocker in Furious to die its sweet nitrous death in Kennedale next Spring....

Let's see a conventional oil do that....rriigggghhhttttt...