Hello. Can anyone tell me if synthetic oil will hurt a second generation rx7. I just bought a 89 convertible and the original owner replaced the engine, however he said he uses only synthetic oil.. SHould I continue to use synthetic or regular oil?

 

i have always heard that synthetic oils dont function good on rotary engines. since it doesnt breakdown the same way as conventional oils.. in its burning process since the rotors need some oil to keep the seals wet.. but check around on other post to ensure ur fancy ..

 

Good quality synthetic oil (Mobile 1, Royal Purple, etc.) is absolutely fine, despite much parroting to the contrary. It does burn cleanly and will not cause any damage or excess deposits. What you won't get is the benefit of extended oil change intervals that is usually one of the big selling point of synthetics. So, it costs more and you still need to change it every 3K. It's still better than mineral oil, but only marginally when changed frequently. I use Royal Purple in my race car, but not in my daily driver (yet). Changing over entails draining the oil cooler, which is just a PITA, so whenever I just happen to need to remove the oil cooler, I'll consider switching to synthetics on my GTUs. Any car getting flogged, however, I would not hesitate to switch. And, once a car has been switched over (as yours has), then I'd definitely stick with it.

 

Can I change from synthetic to regular oil without a problem?/

 

Sure, but why? Synth is better, but often not worth the effort to make the switch. Mineral oil is a definite step backwards and just as much of a PITA to switch. Personally, I'd just pay a little more for the better oil once every three months and rest easier that my engine was getting the 'good stuff' (TM). How much more does it caost per mile? Compare that to gas, and all the misinformed people who pay extra for the dubious benefits of "premium" fuel (which does nothing for a non-turbo rotary).

 

I keep reading that synthetic oil wont lubricate the apex seals, or something to that extent, is this something I shouldnt worry about. I am just paranoid, I dont want the engine to go, the new on only has about 27k on it.

 

I heard that Mazda never tested the use of Synthetic Oil in our engines before, that's why they don't recommend it. But nowadays the NEW AGE synthetic oils that are on the market burn cleaner then ever with no residue. That is why it is being recommended more and more by top rotary engine tuners. Racing BEAT highly recommends using ROYAL PURPLE Synthetics in their Rotary Cars. I have been using Pennzoil Pennzane Synthetic in mine with good results, so I don't see why everyone else shouldn't use it!

 

I bought a '90 convertible 3 months ago. I found , with the original paperwork on the car, a Mazda brochure covering oil usuage. It's titled "THE FORMULA FOR SAVINGS" on the front side. On the back side, it gives recommended oil types and intervals for changing. At the bottom, it states:

"IMPORTANT: Rotary engines are designed to consume a small amount of oil under normal conditions. Be sure to check the oil level occasionally, and never use synthetic oil in a rotary engine."

As this notice suggests, the rotary may have been designed to burn some oil. I believe it is harder to burn synthetic than dino oil. So, maybe Mazda had some internal tests with better results from dino than synthetic. Though, I haven't seen anything published yet.

The original owner of my car used dino oil. I plan to use Valvoline, 20W-50. If you're going to continue using any synthetic, you may want mix it light (20% or 1 qt.) with dino.

 

I dunno where you heard that crap, synthetic lubricates the same as mineral. It's just much more stable at high and low temps, and (in simplistic terms) holds itself together a lot better and for longer.

I which everyone would stop dragging out that old "sythetics won't burn in a rotary" crap. Old synthetics used to burn OK, but leave some deposits, new ones burn perfectly. Mazda don't want to invest the considerable sums of money required to be 101% sure synthetics are OK, so they won't recommend it. Please give this one a rest!

 

it last longer, takes more of a beating, tranfers heat better, protects better and gives better peace of mind....at least for me it does.

synthetic oil in the engine and premix in the tank....my rexy loves it!!!


myron stay with full synthetic dude and use certified premix, go with 8 ounces to every tank full. that will give your apex seals the extra protection you want.

 

That total crap!
Mazda doesn't recommend them because when they were heavy into racing 30 years ago, there was one particular synthetic that didn't burn completely. If they said synthetics were fine except for one, they'd have a legal battle on their hands, so they just said don't use it at all.

I read this in a car mag (Turbo or SCC) 7 years ago. It was an interview with a Mazda exec discussing the future of the rotary after the demise of the 3rd gen in the US.

 

you have to disconnect the oil cooler and lines to drain it ?

 

Synthetic oil does not burn off completely and leaves somewhat sticky residue on the rotors. When I used Amsoil through 20,000 miles and did a rebuild, I went back to regular Castrol20w50. I thought I would have cleaner internals but rather the other way around. Engines that inject oil into the combustion should not use synthetics. If you have totally disabled the oil metering then yes, synthetics would be ok. Engines that have a lot of miles will not benefit from it either because of the smaller molcules. You will have oil blow by.

 

OK guys, the facts are all you need:

1) Pure mineral oil burns. Synthetic oil burns. Hell, even titanium burns (at high enough temps ). But the difference is "AT WHAT TEMPERATURE ?". Agreed, the new synthetics do burn cleanly, but at VERY HIGH TEMPERATURES. I used to use a "common" synthetic oil in my Honda (VTECs need only good synthetics), which caused oil consumption due to oil burning in the engine. Switched over to Motul 300V racing oil, and -until I sold the Honda- I didnt notice any oil burning inside the engine, because the best synthetics burn at very higher temperatures than minerals. So, why take the chance wondering if the temperatures inside the rotary are high enough to completely burn synthetics, when you know that minerals will burn no matter what ?

2) Synthetics do lubricate better, do "hold up" together better, but at a higher cost. Since the only reason most of the synthetic lovers out there use synthetic is to save up on oil money, and since the rotary MUST have oil changes every 5K km, why bother ? The better lubricating effects will be hardly noticeable, but your pocket will sure feel the hit !

3) And yes, if you want to change over (even from one brand to another), you need to remove everything "oil-related": pan, filter, lines, pump, drain everything, put it back in, and drop in the new oil.

 

Contrary to earlier posts you CAN switch from dino oil to synthetic without emptying the oil cooler, taking off the drain pan or any of the other things. All that will happen is for the first change you will have a mix of 85% new oil, and 15% old oil, after 3000 miles when you do your second change you will have only 3% old dino oil and after the third the percentage of dino oil will be too low to matter! The oils are completely compatible.
The only risk I know about swithcing to synthetic on older engines relates to the oil seals - on high mileage engines you will have a degree of oil residue on the oil seals, this residue tends to be dissolved by synthetic oil and can lead to oil leaks.