I talked to a guy a Mazdatrix who sells the Idemitsu, and one of his comments was that they’ve had good luck with the Castrol.  Maybe I’ll stick with it and change more often; I can change it about 5 times for the cost of one change with the Idemitsu.  Besides; I always have some around because I’ve used it all my other vehicles for years with exceptionally good results.

 

Al

The Jap oil is probably every bit as good as they claim it is.

 

 As far as oil goes, the bearings are huge compared to the loads involved. That is one reason that you can overheat the oil repeatedly and get away with it. I have lost 4 rotor bearings since 1980. In the first case (Valvolene 40 weight racing) the radiator got a chunk of tack through it and we lost all of the coolant. The engine finished the race (it happened close to the end) and then could not be shut off. With the battery disconnected and the ignition switch off I had the driver select 4th gear and release the clutch while holding the brakes. The engine stopped, never to turn over again. The distributors and front cover were fine. The rest was scrap metal.

 

 

Oil brand not a factor.

 

 

Not to long ago, maybe 7 years, we bought two real racing engines from the top builder for our kind of racing. One complete for $14,000.00 and an identical short engine for $7,000.00.

I installed the complete engine and went to Mid Ohio. Lost the front rotor bearing housing and front iron (broke the bridge) in the first practice session at about 7,000 RPM, right in front of me. Not even on the power, just warming it up. The following week at Gingerman we lost the backup engine in the first qualifying session. Lost the rear rotor, housing, and rear iron (broke the bridge).

 

Mazda had changed suppliers for bearings and not said anything about it. The new bearings were junk. Thank you very much Mazda. Both were on Redline 40 weight racing oil. Not overheated.

 

Oil brand not a factor. 

 

Castrol invented multi weight oil. Just fine in the crank case. A high quality 2 cycle oil for the OPM would be better. Plus you can run longer between changes because it is a street oil with the correct additives for acid control.

 

The heavy weight oil is right by the door there. The medium weight oil is behind the counter.

The light weight oil is beside the Franklin stove.

 

Lynn E. Hanover