I stick with the stock weight 10w-30. Got 135,000 miles on my FC driven to 7000 daily with that (I bought it with 44,000 mi). Don't forget that heavier weight slows down the oil flow rate. You need to keep the flow rate up to transfer heat away and to the oil cooler(s). And higher viscosity does not mean that it does not break down as fast. Just means that it is thicker. If you have your oil passeges ported and run higher oil pressure to compensate, then ok...



You can buy Royal Purple direct from them on eBay.

 

I have documentation from Mazda sepecifically warning against use of synthetics. The arguement is not a protection issue, more that synthetics cause shrinkage of seals and minerals do not. Who knows for sure?

That said, synths are better oils not doubt, and a lot of guys use it. I use a cheap SF monograde, but I have 2 coolers, 10 litre capacity & change the oil very regularly! The engine comes apart soon after 5 years of track, drags & street thrashing 2 years of which was daily in traffic as my only car. I'll let yas know what its like inside.....

 

As we don't have 10W-30 Mobil1 here I'm thinking to switch to Mobil1 5W50 Formula Rally. It's a fully synthetic oil especially for high performance and racing. Do you know it? Does anyone uses it?

Thanks Dom

 

I'm sure it's quality if it's Mobil 1!

 

I switched to synthetic about a month ago. The car did seem to idle a bit smoother. Synthetic has so many advantages over dyno oil. Plus, from what I've heard from some engine builders, rotarys running synthetic had much less wear on them. I guess I'll see next time I blow my engine.

 

I just ordered 5 qts of Royal Purple, I'll see how it compares to the Mobil 1 I was using. I've used synthetics both oil changes since buying my FD.

 

Yes, it's Mobil 1! So I'll switch next week and let you guys know

 

I switched like a month ago and I drive my car daily. My mobile1 oil is not even dirty. its still carmel color. That cant be bad news.



David

 

Same here. Doesn't break down nearly as fast as the old ****.

 

I'll stick to regular oil cuz I change it every 2K miles anyways. $1.xx/quart. Synthetic is $3xx/quart. If I were to use synthetic, I would still change every 2K miles, so that's a big waste of money.