Diesel oil (15 w 50 has a lot of detergent in it because diesel fuel is nasty. it takes a lot to keep the oil from breaking down. so If we used this in our cars we might not ever have to use the atf anymore.
I know how we can test this. If anyone is a racer and is frequently tearing down motors, then we can have them only use diesel for the whole life of the motor. then when they break it down again, they can let us know if it worked. How much carbon was on the apex seals. They make synthetic too.
Or if anyone is planning on a rebuild in the next 10,000 miles or so. you can start usiging the oil now. and see what happens.
any one up for this?

 

Interesting idea. I wonder if the detergent would harm anything. People say 20w50 is best, well, some cases, i forget what circumstances. Does that much of a difference matter?

 

If diesel oil was best Mazda would have recommended it. One reason diesel oil is different to gasoline oil is the amount of soot generated by diesel combustion which gets into the sump. The dispersant in the diesel oil additive package prevents the soot from clumping together. I don't see any advantage for using such an oil in a rotary.

 

good bump for a 6 year old thread


There are several of us old timers that have used diesel designed oils, and as long as they meet the SM requirement are perfectly fine to use in a rotary or gasoline engine