Have a rebuilt engine running on Castrol 20w50 for about 10k miles. I have no omp [just premix], no cats and I was thinking of switching to synthetic oil. I drive maybe 5k mile a year. any suggestion on what grade and brand synthetic oil should I run. so far the researches that I made doesn't give me a straight answer. I want to know from first hand people what you guys are using.
Note: car is running on gt35r at 15psi if that matters.

 

I'm also not running an OMP and only premix. I used to run Castrol 20w50 but recently switched to their synthetic Edge 5w50 but I did it around the end of last summer, went to one lapping and one autocross day then stored the car afterward so I can't really comment on long term use. Made around 1200mi since I switched but so far the car was a bit easier to start on colder days otherwise I feel like fuel dilution is still the biggest issue with oil in these engines and the reason for closer oil changes requirement.

While lapping, my oil temps where the exact same as with 20w50. Also the Castrol Edge 5w50 had good concentration of zinc !

 

Other than the extra cost, there's really no good reason NOT to run a high quality synthetic oil in a rotary that exclusively runs premix. I made the switch to Mobile-1 Advanced synthetic 10W30 on the brand new 13BT that I built up for my FC after the initial 500 mile break-in oil was drained. Can't give you any feedback regarding rotary specific longevity & wear yet, as I only have about 5K miles on that motor now. This motor dynos at 350RWHP/330Ft-Lbs, and I'm running premix via a separate tank thru the RA adapter & stock S5 electronic OMP, controlled by my AEM Infinity ECU. Motor & turbo seems to be happy with this oil. Despite going synthetic, I still change my FC's oil & filter at the traditional 3K mile increments, but that's only because I'm concerned about fuel dilution.

FWIW, I've been using the same Mobile 1 synthetic oils in all of my piston engine cars since around Y2K, most of which I kept past 100K miles with zero oil related problems. Typically changed my synthetic oil on 5~6K mile schedule on those. Two of those cars remain in the fleet and are still running strong, not burning a drop of oil after being passed down to my kids - an '03 Mazda Protege5 (2.0L, 190K miles) and an '03 Nissan Sentra (1.8L, 152K miles)

 

 

 

what grade Valvoline Vr1 high zinc are u using?

 

I am running 20w-50 Vr1 conventional oil. I am not a chemist nor do i have any background in oil analysis. Valvoline claims to have anti foaming properties and I CAN say.. When i'm cruising down the highway in 4th gear at 4500-5000 rpms my oil pressure does not drop like it did with the Castrol...

-M

 

I guess im gonna try the vr1, advanced auto got them locally...

 

I've been running only synthetic since the late 90's and I have never removed the OMP or premixed. I've owned 5 RX-7's and have never had a single engine go out.

 

Iv'e been using synthetic oil for over 30k miles on my rebuild. I still have the OMP running with no issues. I was using Royal Purple 10w-30 for the longest until I made the switch to Idemitsu. I am also using premix.

 

 

thanks man, the store wanted like 42 bucks....

 

also I noticed when I got the oem oil filter from mazda it used to be black, now its white anyone noticed that?

 

I do not run synthetic in any of my 7's.Not against it honestly, but I've been using Castrol GTX 20W50 since the late 90's with zero issues.

 

Personally I run 20W/50 Castrol GTX with Mazda oil filters. I buy filters in bulk from Atkins Rotary or Rotary Performance.

Also, currently on Amazon it's like $17.50 shipped for 5 quarts of Gastrol GTX.

Easy to buy filters in bulk when the RX-7 and Miata use the same oil filter.

 

I've been running Shell Rotella T6 Full Syn for years, not sure about wear or tear, engine is still running since its last rebuild (about 8 years ago). Shell Rotella T6 can be found at Walmart, it used to be cheaper, price has gone up; but still not as expensive as the other leading brands. I would run Valvoline Vr1 if it was easily accessible. In this area, finding Vr1 locally is NOT an easy task, and when you do, its like $7-$9 per quart!!

 

I ended up getting vr1 with oem filter.

 

You'll be happy with the Vr1.