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Just got my RX-8, 2011 model R3, I am considering using Shell Rotella 15w-40 T4. It is catless, some people swear by using diesel oils, does anyone else have any experience with the Rotella products or similar?
I use Shell Rotella T6 in all my vehicles but the RX-8, and have for many years, including motorcycles, supercharged and turbos, where it's weight qualifies. It can be purchased at Walmart in 4 liters jugs at reasonable cost. For the Miata, it uses a full container. You'll need two containers for vehicles over four litres.
I do not use it in the RX-8. For my R3 I use Castrol GTX 5-20 or 5-30.
As a side story, my Mazda dealer in Los Angeles is flexible, and happy to do an oil change with 5-30 for the R3. My Mazda dealer in Phila /S. Jersey flatly refuses, and shall only do an oil change with 5-20, so I do not use them for oil service when I want 5-30.
Lucas Oil Semi synthetic 10w40 is A3B4 approved =Mineral based
per my long research for my 09 Rx8 oil I use!
Or 15w40 if you can find it with A3B4 spec.
Last edited by Alain Miller; 05-28-2020 at 10:53 AM.
Reason: update info
Lucas Oil Semi synthetic 10w40 is A3B4 approved =Mineral based... is the go to Oil
per my long research for my 09 Rx8 best oil to use!
Or 15w40 if you can find it with A3B4 spec.
Interesting opinion. Claiming a "best" oil around here is pretty bold. Got data?
I have ran many track days with rotella t6 5w40 and royal purple xpr 10w40 and both oils proven to work well for that purpose. I am not convinced the xpr is worth the added cost but I got a deal on a large quantity of it for about the same price as t6.
Testing on the dyno has shown hotter and thinner oil makes marginally more power. I have ran 0w-20 in race conditions also. Potentially there could be a compromise in wear protection in doing so but I expect the motor would eat the side seals long before the bearings.
oooh an oil thread. My 2 pence is xW40 or xW50. There a bunch of great high quality Walmart Supertech 10W40 to be had if you're willing to wait in the lines at the store. Now that my engine warranty is up - I'm moving to 10W40 for Summer and 5W30 for Winter since there isn't any cheap SAE 5W40 or higher to be had as conventional oil.
If you look around the US EPA's mandate for low viscosity oil to maximize MPG, the RX-8 manuals ex-US recommended this:
for racing I wouldn’t recommend less than xW50 along with a finely balanced rotating assembly, clearanced bearings, and increased pressure mods.
Castrol gtx20w50. I like for street use here in Arizona.Cheap at Walmart for short intervals. I used Kendall 20w50 in my old 1983 sb in the 80s and 90s in Boston and upstate NY year round fwiw.
Walmart has stopped selling many Supertech branded conventional oils like 5W30, 5W20, and the like. All now are blends or full synthetic. So the price of a jug o' oil now has gone up $5-6 to $19. Not sure if a blend is good for the RX-8 but thought I'd point out the changes afoot at the Circle K wrt conventional oil choices.
10-20-2019, 11:43 AM
