Well even if its not ive been using it with good results so far.So heres the deal.During the summer I was using 5/30 and 10/30 oil.But it was just too thin.The engine ate like half a quart a week and it ran way hotter than I remember it running.I talked to a friend of mine who happens to know a lot about cars.He suggested i get thicker oil.He said it would stand up to the heat better.Especially when he saw how hot the rotary gets.He said in theory that the thicker oil should last longer and should also cool the engine better.So I bought a quart of 10/40 synthetic and put it in.The car runs better,stays cooler,and ive checked my dipstick numerous times to see if the engines been eating up oil and the dipstick barely changes.I already know about the oil injection into the combustion chamber and that its perfectly normal.My question is this.Im not running full 10/40.More like a mix of 5/30 and 10/40.Im coming up on an oil change and I wonder if running full 10/40 will change the results of my findings and also if it will be detrimental to my engine.

 

Most peope don't recommend 10w-40 because of the additives. Use either 10w-30 or 10w-50.

 

hmm.well ive tried to use 10/30 already with somewhat questionable results.What additives are in 10/40 thats bad for the rotary? Basically what does it do to the engine thats bad? you also mentioned 10/50.So I take it that 10/50 is thicker than 10/40 and no harmfull additives? if thats true then 10/50 is for me.The thicker the more protection for my baby.And the cooler it will probably stay.Right?

 

The thicker the oil, the longer it will take to warm up. If you are in Colorado, you should run 10w-30 during the colder months. Then, if you want to switch, switch to 20w-50 during the warmer months or on tracks days if you put the car on a track.

 

I normally run 20w50 Castrol dino juice during the hot seasons, and during the cold, run 10w40 dino. I have recently switched to 15W50 synthetic since I removed my OMP.

 

No, its not ok.

 

so synthetic 10/30 in the winter and synthetic 20/50 in the summer.sounds good to me.

 

I use 10/30 syn year round. 10/30 is all my car has ever seen. At 85K, I have no complaints so far.

 

what is wrong with 10/40? Ive been running it all winter?

 

Read the above statements for your answer.

 

I read and see that it says it has harmful additives... but why would it be worse than 20/50 or 10/30 dont they have the same additives? I thought the only difference was in weighting and viscosity?

 

No

Wrong again. Not all motor oils are the same.

 

so im not supposed to run 10/40 because it has some special additive that all the other weights dont? does anyone have any information what this additive is or why it shouldent be used? does it eat seals or bearings or something?

 

For what ist worth,I have been using Pennzoil 10-40 for over 20 years in all ( except my 8) of my trucks, cars and motorcycles and have never had an engine(rotary or piston) failure.

 

this is why im asking, i see ALOT of misinformation on these forums and I want to see if anyone has any real facts to back it up or if its just hearsay

 

Here is a good link for you to read. It will answer all of your questions. It is more then you ever wanted to know about motor oil.

http://www.vtr.org/maintain/oil-overview.html

Quoted directly from the site.

 

BYW, On my cars & trucks I change the oil every 3 months or 3000 miles. I change the oil every other ride on dirt bikes.

 

For a start, it's considered a bad idea to use any kind of synthetic oil in a rotary. IMO you should be using a mineral based oil. Any of you that say you shouldn't use 10w-40 because of the additives should check the kind of crap used in synthetic that won't fully combust, leaving lots of ***** in your housings.

I recommend Castrol GTX 10w-40 (Don't think Castrol make the 10w-30 anymore!)

But hey, what would I know :P

 

What does Mazda recommend on the FD 1999+?

I have been using 10W - 30 since this is what Mazda & my mechanic recommends. However, as in Greece it gets really hot I was wondering whether I should be using something else...

 

Well while we are on the subject how about straight 30 weight in the summer? I am guessing it would have no additives at all since it doesn't need to morph or whatever the 10wXX does.

 

No don't run it, everytime you do god kills a kitten!
That and it's the $hit oil.

 

I use Mobil 1 15W50. Mobil 1 synthetic is all my 13,000-mile KDR street-ported motor has used since Jan 2003.

 

maybe the discussion of the additives maybe a myth??

not sure...

but my BMW M3 uses 10-60 (yes it is a real weight and only castrol makes it and cost $8-9 aquart!!) and the oil change recommended by BMW is around every 15000 miles!

 

Mazda's ONLY recomended Oils for the FD are 10-30, for most regions, and 5-30 for climates w/Average temps BELOW 32degF (0c) they do not recomend anything heavier than 10-30 for any climate range - I run Castrol GTX 10-30.

 

here is a group of people studying Mobil1 (on the same site they are currently comparing Mobil1 vs. Amsoil)

http://neptune.spacebears.com/cars/stories/mobil1.html

the interesting thing about the analysis of the data and oil is that they concluded 8-15000 miles between changes and that "topping off" the oil and changing the filter was just as good and that changes every 3000 miles actually caused MORE wear on the engine...