Synthetic or not
 

I've been reading my owner's manual (i just got an 1986 NA rx7) and it says, concerning engine oil, API Service "Fuel Efficient" SF grade (Do not use synthetic oil).

why shouldn't i use synthetic?

Mazda has always recommended against synthetic motor oils, despite overwhelming evidence that synthetic oils are perfectly safe and effective in rotary engines. The stance has caused a lot of misguided people to invent fiction about the supposed inability of synthetic oils to burn or burn cleanly, and thousands of little parrots to repeat that nonsense ad nauseum. Synthetic oils do burn and (in my opinion) the quality ones burn as clean or better than mineral oils when the car is operated as intended (not driven like a grandma; seeing the occational redline). The real question isn't if synthetics are better or safe (they are both) but an economic issue of whether it makes any sense to pay the premium. Mineral oils are extremely good and relatively cheap. The benefits of synthetics are mainly to be seen in the very long term and they cannot undo wear already present. So, unless you have a relatively new engine (ideally, just broken-in), synthetic oil will be a waste of money because it's like closing the barn door after the horses are out...you can't un-wear a worn engine. Another matter to do with economics is the oil change interval. Synthetics do simply last longer, which is a potential benefit, but it won't stand up to fuel contamination any better than mineral oil. In turbo cars, especially, this can be a big factor due to all the blow-by into the oil system. In that case, you need to change synthetic oil just as often as mineral oil. For non-turbos, however, a healthy engine can actually get away with extended oil changes for synthetics...often 6 months to a year, provided you still change your oil filter at the usual frequency. Again, this is only a benefit to NAs that are still relatively fresh; not your typical 100K+ engines that are getting tired.

To recap: Synthetics are good but may not pass a cost/benefit analysis unless you have a fresh but broken-in engine, and even then it's not a slam dunk economically. I don't use it in my daily driver with 144K miles because that would be stupid. I will use it after break-in of the new motor waiting to go in its place, however.

^^Knowledge^^

ive got barely 28k miles on mine, think it would be a good idea?

rx7 do burn oil as they go so i think it will end up being extremely expensive as i burn oil i must add oil so it's almost as if im pertually and slowly changing the oil... until i actually change it around 3000-4000 miles. i think mineral is the way to go

mine burned a little more than half a quart over about 1300 miles under mildly spirited driving

Wow, Blake just taught me something new. Thanks.

Royal Purple FTW! Check out racingbeat.com they have a long article on the site. Synthetics are fine on Rotary engines, and they give you a 2% hp gain.

Blake, you left out that synthetic oil has changed quite a bit since the FC came out. Some of the cheaper ones of the day did have an increased rate of carbon buildup, but, like you said, if the motor sees redline a minimum of once a day, this is a non issue.

And for the fact behind what is in your owners manual...

Mazda had neither the time nor the money to test the motor using synthetic oil, so they simply avoided any potential issues that may have caused by putting that in the owners manual to have a crutch to fall on should thousands of people become rendered pedestrians because they used the "wrong" oil in their cars. Simply, they couldn't test and approve it so they tried to avoid it all together.

I suggest synthetic now, but please stick to a high quality. It might not unwear a worn engine, but it sure as hell can slow it down.

If you still feel hinky about using synthetic, go premix and then you have no reason not to, since it won't be getting into the combustion chamber anyway.

-Maniac

cost analysis aside.....I have used RP synthetic on my periport and never had a problem as a matter of fact I was sponsored by Royal Purple and they asked us to analyze the engine when finished racing , which we did with great care..taking measurments all the time...NO wear was present ....it seems to work to our benifit
as for horspower gains nothing was noted, however in extreme temp the oil did seem to thin but never lost its lubricity properties.

Having said that I have also used local mineral based oil (their best ones) and had great results too...so it is mostly based on your own budget, as the engine will meter your oil unlesss of course your using a blocked offf metering pump and runnning pre mix, which is fine for you to use a expensive oil......I think the benifit to your engine is worthe the cost offset.....

I was also sponsored by Royal Purple back in 2001-2003. David Canitz, Engineer and Product Rep, is a friend of mine. He has been racing rotaries for years using his own products, so the company has 1st hand knowledge of rotary engines. Every product they make is awesome, in my experience. Motor oil, gear lube, grease, premix...the only one I have not tried is the assembly lube. RP's main customers are other oil companies who use RP's industrial products to lubricate their plant machinery. I find it quite remarkable that big companies making lubricants themselves buy lubricants from another, smaller company for their own use! The automotive line is just a secondary market for Royal Purple, but they are the best products there too, IMHO.

When running synthetics, I use RP exclusively. Rob, however, has been using Mobil 1 for what seems like forever (15 years?) and is content to stick with it. I haven't used Amzoil for years, but I never liked the crap when I did. Just my opinion.

HAHAHAHA your right the rep told me the same thing....that RP is used by all the big bou=ys to lube their oil platforms....In Trinidad oil industry is huge and that is where it is used mostly..............but in our race car at 100 F it stood up just as well

:icon_tup: sweet, I was just about to ask about using royal purple in my fresh engine (just turned 5k miles) but this answered my questions. amazing what a search can do, huh?!?

There is a small amount of truth to the not burning cleanly thing. Back about 10 years ago my friend and I asked Valvoline, Mobile1, and Amsoil to send data sheets for their oils. The ash content in Valvoline synthetic was astronomical! I am talking several times greater than their mineral oil. Amsoil was pretty much 0 and Mobile1 had a little more. I believe Royal Purple is also pretty close to 0 as well but I havent seen a data sheet. Who knows if Valvoline has changed, but I still stick to the RP and Mobile1.