What is the best oil and coolant for a 13b
 

I've got a Rx7 s2 13b carby and it's time for a good service. Does anyone know the best coolant and oil to use for my baby.

Most people I know go with Castrol 20W-50. As for coolant, after my engine debacle and after opening it up and seeing what water does to the coolant passages I am going to use Evans NPG. I guess it is a pressureless coolant system that does not corode things and works very good. I haven't done much research on it though.

Were you running straight water or something? If you mix ethylene glycol coolant 50/50 with water (like you're supposed to) and change your coolant every couple years, you should not get any corrosion.

Evans NPG is propylene glycol coolant that you don't mix with water. But it's like $50 per gallon or something like that... pretty expensive. It's main advantage is that it boils at a much higher temperature, so you can run a zero pressure radiator cap.

As for oil, I also use Castrol, but I use 10W30. I think 20W-50 is way too thick and will cause a lot of wear during cold starts.

Interesting to know. I had not researched the Evans stuff so I didn't know how expensive it was. I think I will still switch to it just because there was enough corrosion in my engine that I do not want to have any of that after I rebuild it. I also wasn't using distilled water so I bet that caused a lot of the gunk in there.

i uses the premixed (50/50) anti-freeze they have at walmart
I cant remember the name, but it isnt crappy at all.
mobil 1 15-50w (premix)

yeah for oil i use 10W30 for coolant i just use like prestone or whatever from pepboys i just flushed out my radiator yesterday

You shouldn't get any corrosion if you use 50/50 with distilled water and change it every couple of years. I've torn several motors apart and have never seen corrosion or deposit buildup from running this mixture. There are corrosion inhibitors in the ethylen glycol to stop this type of thing.

I run 50/50, but might change to 60 water/40 coolant this summer or something like that. Depends on how lazy I am.

CASTROL GTX 20w50 or 10w40... i use 20w50... PRESTON coolant... flush out the old one and just add 100%... and add water in the overflow tank

100% coolant?? Terrible idea! The heat transfer properties of ethylene glycol is *much* worse than water. That is why a lot of people run more water than antifreeze, to make their engines run cooler.

You're not supposed to go over 75% coolant....
Most people use more water to run cooler. People mix in coolant/antifreeze to prevent corrosion and to keep the water from freezing (for people in colder climates).

I use 65:35 water to ethylene glycol (regular green anti-freeze) mix all year round here in south Florida. Also, be sure to use distilled water only.



Mobil1 15w-50 full-synthetic in the engine and 4oz of Marvel Mystery Oil per gas tank.

i use that new coolant they got out, i forget the name but it the orange stuff!! as fo oil i live in Vermont so i use Castrol GTX 10w40 tends to be more suet for VT weather(i dont drive it in the winter either, storage)

well... my car was 100% coolant... but prbably down to about 70% to 30% water... its not all that bad... my GSL-SE ran cooler with 100% coolant...

Thankyou everyone for the words of wisdom. Before I make up my mind I still consult my rotary specialist. I'm thinking though i'll go with the Preston and 10w30.

I spoke to a rotary mechanic today and he claimed he uses Penrite 30-60 or 20-60 on all his rotars. He said it will keep the engine in good working order for a long time. What do you guys think? He also said that the best coolant to use is straight from the Mazda dealers. Now I'm in a little confusion, is he right?

That Penrite gear is way too thick IMO, isn't HPR40 something like 25W-70??? When I was running the OMP I used Penzoil GT. Now I don't run the OMP I run Motul 6100 Fully Synthetic in the sump and TC-W3 Marine outboard 2 stroke oil through the fuel at 180:1 for street driving and 150:1 for track, as for coolant, the Mazda genuine stuff is good, but for a lesser price you can get something just as good, I use Castrol Radi-Cool and it sems to be doing the job IMO

Thanks once again!

preston is fine.... original MAZDA stuff is the same stuff as PRESTON... you wanna spend extra $$$ for the same stuff go ahead... that extra $$$ could be saved for a new RACING BEAT HEADER....

The VR-1 race oil 20-50, and staight water w/ VP coolant additive

I was told not to put synthetic oil in my 13B, i did and the car was acting funny like going to high in RPM when i turn on, also it used to go off so , if u wanna used it go ahead i recomend the Castrol 20W-50 im using that on and its working great