I think you are totally missing what the definition of cold is. Freezing and below. That is when you run into substantial startup viscosity issues with 20W-50.

 

The only reason to use a 20w-50 is for heat dispurtion. If you are running two oil coolers then heat dispurtion isn't an issue.

Your engine will last longer on 10w-30, trust me, I know this.

Ask me how you say? Read below.

More then you ever wanted to know about motor oil:
http://www.vtr.org/maintain/oil-overview.html

 

10w30 all day all long.

 

10w30 all year for me also.

 

ok i think i will listen to the manual as well as the majority of people here and stick w/ 10w-30, unless someone has some info on why 20-50 would be beneficial

 

Castrol GTX 20-50 in all the rotary cars I have ever had, and never oil problems. No hard data but years of good results..

 

If thicker is better, lets all start running straight stp or motor honey

 

Most of the Texas RX-7 shops recommend 20/50. It's hot here, + fuel dilution issue.

The real issue here is, has anyone ever had an oil related engine failure due to running the "wrong" motor oil. I don't think so.

 

well in fl sometimes after a long day on a hot highway or stop and go you may not get 50 psi at 3,000 rpm. if that happens then 20-50 will up the press to spec. it is all about function. you want the lightest oil that meets the pressure req. if it happens to be 5-30 like most newer cars so be it. and yes something else usually gets our cars before any oil issues do.

 

if you change your oil frequently....fuel dillution should not be an issue.........mazda says use 10w-30....thats all my 7 see's......and im in florida..

 

rotary engine burns oil while it burns fuel. Someone who owns rotary specialty shop told me Castrol 20w 50 is completly burned through combustion. I use 20w 50 during the winter and 10w 30 during the summer.

 

Good point. I use "good" oil, but I still haven't heard of anyone losing an engine from bad oil.

I hesitate to post this since I don't want to open the old can of worms, but... I have been using synthetic since I think the rumors that it is bad for the engine are false. There is another good reason not to run synthetics (cost), but I basically do not believe that it gums up the seals. However, being certain of that is a difficult state to achieve. I recently had my engine torn down (broken apex seals from running too lean -- NOT oil related) and after 25K hard miles (street/circuit car with 370RWHP) of running Royal Purple (20W-50 and Racing 51), I don't see evidence of gummed up seals or any other problems. That isn't necessarily proof, but it reinforces my belief that synthetic is just fine for use in rotaries.

-Max

 

Mobil 1 10W30 in Ohio.

 

Mobil 1 synthetic motor oil.

10W30 fall/winter/spring; 15W50 in the summer

Drain intervals range between 4000 to 5000 miles.

The synthetics allow longer service between changes.

I live in central IN.

 

Good info Max!

 

10W30 Mobil 1 full synthetic here.

I used to change the oil every 1k-1.5k miles and at 80k my motor poped anyway.
I still change it around that mileage, will se how long this baby will last

 

I usually end up running 10w30 in the winter because if I don't, I'll get ridiculously high oil pressures at start up. The local rx-7 shop (mazcare) puts castrol 20w50 in though during the summer months. They generally know what they are doing.

 

Thanks for the link, former porsche. If everyone here would read that, synthetic would justify its higher cost just because of no ash or zinc that would cause deposits in our oil injected engines

 

in the mazda manual it said "synthetic oils WILL damage rotary engines. be sure to use only nonsynthetic oil in your RX-7." oh ya and it also reads "using oils of viscosity besides those recommended for specific temperature ranges could result in engine damage" is also reads " the quality designation SG must be on the lable" the chart in the book recomend only 5w-30 for freezing and below temps and 10w-30 for about 0 def F to over 120 deg F

thats strait from the manual that came with my rx7 and im sure mazda spent millions on finding out what oil is best to run it their car

me personaly im going to run 10w-30 and just change it regularly like what mazda said to do I also have an r1 so ive got an extra oil cooler so heat isnt as big of a problem

 

FD3SR1, I respect what you are saying as a motivation to choose an oil for yourself. But the reality is that there is a lot more to the story than what it may seem from those statements in the user manual. The manual includes a lot of disclaimers to cover Mazda's ***. It isn't quite the "optimum care guide" that it may at first seem.

-Max

 

You know, even though I run 10w-30 myself, and stay away from synthetic, that's more of a personal preference and a scaredy-cat approach that I take. The you-can't-go-wrong way haha.

But the synthetic argument like Max said, people claim it can leave deposits, but this has never been proven, in so much that I've seen or read. On the contrary, however, I distinctly remember reading WHY Mazda wrote no synethetic use. (Where I read it I can't remember, but I'm sure Mahjik can work his magic haha and come up w/ a link for us! )

When Mazda was testing rotaries, they used a host of different oils, and it just so happens that one particular brand of synthetic that they used caused problems. Due to legality issues of excluding a single brand by name (which would have been a lawsuit mess), Mazda simply said NO to ALL synthetics, despite no evidence of any problems from any other synthetic oil. So that's the story on that.

Any manufacturer will tell you using this or that oil that isn't what they recommend can damage your vehicle cuz they're covering their butt, again like Max said. And in fact that runs for almost every fluid you put in your car.

Example: my 86 accord manual says use ONLY genuine honda power steering fluid. You know that EVERY honda they make uses the EXACT same power steering fluid, irregardless of year, model, or engine size? Talk about "specifically designed for your car's needs" hehe. It's simply a liability and revenue issue. I assure you my steering won't all of a sudden go shot if I used generic brand power steering fluid lol. And the same goes for oils. Granted, if you drive a Viper and use the low-end oils, you may have an issue. But I'd venture to say even Castrol Syntec natural (not the synthetic) - being the best non-synthetic oil you can get - would be just fine mechanically in a Viper. But again, liability and revenue come into play (here moreso that Mobil One has an exclusivity contract with them lol)

 

whats the final verdict?

 

Jason, I know that article very well. Sometime in 02, I think, when this discussion, came up, I was quoting it extensively in regards to ash content.

 

In So Cal, my motor is going to fail from cooling issues LONG before it fails from running the wrong type of oil.


Tri-Point told me to run Mobil 1 20w-50 when they rebuilt my motor. It's hard to argue with their expertise.