After EXTENSIVE reading on the subject on this forum, I have decided that sythetic is okay for my car, and have learned that the oil weight is set in stone via some fed mandated BS. Still leaves me with a couple key questions though:

1) I live in Seattle. Never gets truly hot. Will I see a benefit from 5w-30 in any arena? (what most people seem to run) Do I lose hp/economy? Is it appropriate for the climate? Or should I stick w/ 5w-20?

2) Royal Purple or Amsoil? Most people here seem to prefer RP, but no one complains about Amsoil (I will not do Redline). Anyone have good reason to pick one or the other (I accept science and relevant experience, not idle conjecture or blind brand loyalty!) I am picking one and doing it for all fluids because I'm at 30k.

Thanks!
-flomulgator

 

They said 5w20 because thats what Ford use, to get better emission and slightly better mpg.

5w30 can protect your engine parts better.

I use RP, never had any EXP with Amsoil. You can ask speeddemon32, his sponsor is Amsoil.

 

I'm more worried about the heat of the engine vs. the climate, even living in Houston. I'm running 5W-30 in the winters and I may switch to 10W-30 in the summers.

In your case, I think 5W-30 is a good all around choice.

 

Thanks for the reply! I had heard that about Ford. The fed thing I was referring to was that you had to recommend the type of oil that you used in the vehicle for emissions and EPA MPG ratings, and it had to be printed on the oil cap. Thus the one (wrong) weight. On a side note I wonder if they are pulling that w/ diesels. If I put anything other than 20w-50 in my old diesel it would Asplode.

Also, you have pics of your car w/ the MS v.2 wheels posted anywhere???

 

5w = viscosity when cold
30 = viscosity at operating temp
In your case you want to increase the last number, not the first. My cousin in Houston has the same issue w/ his BMW 330. I think he runs Xw-40.

Thanks for weighing in! Sounds like no one serious about this car actually recommends 5w-20 under any climate! Oh and like your avatar.

 

Let me be the "one" who would recommend 5W20.

Don't be too quick to bash that oil, just because Ford recommends it - the new SM rated 5W20 oils are a great product. The specs are very hard to achieve with old fashioned dino oil, it needs the temperature stability of a synthetic, and most name-brand 5W20s are a blend, even Motorcraft, Fords own.

That first number IS measured "cold" but the cold is a relative one, and well above room temperature, 40 degrees C! (100+F) and only gives a general idea of "thinness".

The major worry about saying "you can use 10W30" (which you absolutely can) is that the 10W30 spec is readily achievable by the lowest cost components, from dino oils and with a minimal/cheap additive package.

Thousands of real-world studies and analyses have proven that a 20 weight oil is NOT "too thin" - the results show excellent protection. Tribologists are fond of the saying "....no oil is too thin at cold startup".

In general terms a thinner oil will provide -

quicker flow to parts
faster oil circulation
less filter differential pressure
faster filter bypass closing
more cooling

if you can also achieve good wear protection, it's a win-win.

S

 

I read that about 5w-20, that it is essentially already a synthetic at least in part. Your answer slightly confuses me though. I agree with everything you say about the 5w part of the weight and think it applies very well to brillo's situation. Hell if I lived where it sounds like you do I would run 0w-X.

However, it is the 20 part I am most curious about. What temperature is it tested at? (shocked that they test the first # at 40 rather than something applicable like -5 C). Does it offer an equal level of protection to 30 at a given engine temp? What real world temp do these oils diverge in protectability in an renesis rotary? Can we draw a Mason Dixie line on the map and say, "it's too hot down here to run 5w-20 but up north go ahead and get that extra 0.5 mpg"?

 

I am with you Stealth!!!!

Some more data on this topic here

https://www.rx8club.com/series-i-tech-garage-22/oil-mixing-q-110594/

 

So I read that whole thread, and all your posts in it. So the flow thing makes sense, but then again we have two oil coolers (and I live in cool weather where the would work well). If it can be assumed that oil temp can be maintained.....

That's all kind of a tangent though (how well the oil itself holds up at high temp). I'm more curious about how well a given weight (2nd number only) of oil protects a rotary at a given temp. Because if a 20 holds up just as well in 90 (max) degree weather and semi-hard driving as a 30 then I would go w/ the 20 for added benefit. If it turns to useless **** like MM worries about then I'm going with 5w-30.

 

as my ramblings in another thread--a 5 w/20 will not let you maintain normal oil pressures using mazda's specs. Pressure IS important. Flow is important also --it has to be a balance between the two. Even the mazda dealership in my hometown does not put 5W/20 in-anymore. they use a 5W/30.
And the debate will continue.
olddragger

 

Oldragger-
I have read your point before (most recently in the thread that Jax pointed to). I'm just going to straight believe that because I've read enough logical and intelligent stuff from you before. The part about your dealer......you do live in Georgia. If I were a Georgia dealer I would run heavier. The question is about location/abient climate the car experiences.

All that being said, I am trying to get this done today. So I am going to go w/ 5w-30 Royal Purple. I figure the advertised increase in lubrication and flow that you get out of going high end synthetic will offset the weight increase. Unforunately I have no baseline data so any reports from the field will be given by the offensively inaccurate butt dyno.

I do not, however, want this thread to die w/ my one oil change (I do plan on changing the oil again!). I've seen some good points but they all attack the oil from a different angle. Some measured data would be really cool to see. It would also be neat to see what RotaryGod vs. Zoom44 would have to say since they both seem to know a fair amount and they live in vastly different climates.

Also I got very little in the way of Amsoil/Royal Purple. Why do you guys choose what you do?
-flomulgator

 

availability is one reason-amsoil is a little harder to get here. RP has an excellent rep.
Have you changed the transmission oil yet? If not do so. You will be surprised at the difference it makes in your shifting--thats a change that is very obvious. It is the same way in your engine.One just can't experience it as well.
I can actually feel the difference(performance wise) between a 5w/20 RP and a 5w/30 RP. I can feel a stronger improvement from dino to Rp.
One hint-- jack your car up on the drivers side before you drain your oil--do the drain thing leaving you car jacked up higher on the drivers side. let it drain for approx 45 mins or so--it will be a very slow drain! But this way you can get a lot more out---over 5quarts (with filter change also).
Another hint i will give you--place high powered magnets on your new oil filter. dont laugh--have you ever dissected an oil filter that had those on it? It is like having a BIG magnetic drain plug. It will capture a lot.
olddragger

 

I was already going to get the gear oils in RP, that was an easy one!
I had heard drain both coolers by jacking up both sides? I had not tried anything but level yet. I had done a 1 quart "sacrifice pour" where I leave the plug off. Made a big difference in color between the start and the end of the extra quart. Now I hear of people doing one or more total flushes with throw away oil to clean all the gunk out.

How do I do the magnets? What kind/size of magnet should I get and how should I mount them?

 

look at sumnmit racing site and just type in oil filter magnets or if you have an old computer hard drive lying around just bust it open and us the magnets that hold the hardrive.
OD

 

If you worry about the heat, use a 40 weight oil. 5W30 and 10W30 behave the same at engine temp W stands for winter, and 5W is less viscous at low temperature than 10W, hence you engine starts easier).
BTW - I run 5W-30 in winter and 10W-40 in summer.

 

bx40--have you measured your temp difference between those weight oils? I am curious as to the difference it makes. I do know that when I change to royal purple i had a 10 degree drop in overall temps.--impressive.
olddragger

 

Got about 4.7 quarts. Probably couldn't jack it up as high. Still, that's way better than the normal 3.7! Also did a sacrifice quart, which also helped clean out the old stuff. Thanks for the excellent tip!