Good day,

Anyone else using 15W-40? My shop told me to use 15W-40 every 2500 miles, problem is all the 15W-40 oil that's available are for diesel engines. Can someone provide some insight on this? I have a 93 FD single turbo street port.

Thanks!

 

Yes Rotella T4 15W40 Diesel Engine Oil, as recommended by my engine builder (IR Performance).

 

+1 Rotella 15-40

 

Been using it for years both as breakin oil and regular use. Its relatively cheap and easy to find. The only downside is they changed the formula and removed the zinc additives some time ago but we have seen no issues. For higher hp or those wanting a premium oil we recommend Idemitsu.

 

whats the difference in the oil with the diesel specification?

 

^ My understanding from a diesel truck friend is that it’s some better at removing deposits left behind by the less refined fuel.

 

Thank You All!

 

here is the factory manual blurb, imo going from 30 to 40 at high power is probably not a bad idea. ideally you'd want to keep the 10w, but you do what you can.
the API spec is SG/SH which is old, they are past SN now, and it is backwards compatible, so you want the current stuff.
Also the newer cars are doing away with the temp chart, the engine runs at the same temp all the time, so it doesn't matter.

oh and this is for the 1993-1995, for all we know the later cars used something else

 

I use the Mazda designed oil; Idemitsu 20-50 down here in hot Houston. I run up to 18+ boost.
https://www.idemitsulubricants.com/p...-20w-50-rotary

My OMP uses the Rotary Aviation adapter which uses an external tank to run Idemitsu premix oil.
I also run some premix in the tank, .5 oz per gallon of gas.
https://www.rotaryaviation.com/store..._Adapters.html

https://www.idemitsulubricants.com/p...-rotary-premix

 

Has anyone done an oil test from Blackstone or similar on the Idemetsu?
I'm a little wary of using racing oil in a street setting. The additive package usually doesn't have much in terms of cleaners and such.
Shaeffer's used to have a 10-40 synthetic but doesn't seem like they have that in a street oil anymore. I use their 30 weight race oil in my Spec Miata.

 

Excellent idea... will start on my first oil change!