As working in a oil distributor, i really cant believe this.
So the base is a mineral oil. What kind of additives are added into the base mineral oil? Mineral oil has better lubricating elements than a synthetic oil due less use of additivies (synthetic oils use very high additivies to make the oil withstand longer servicelimits). But the actual lubrication suffers from the additives used in Synthetic oil partly because the very high surfacepressure. Its great that we can start the engines in -25 degrees and the oil still keeps its formation in over 100 degrees plus we can drive almost 20000miles with the same oil. But oil cant do everything.
Main question; How long can you use your mineral oil in the engine between the services?
I understand the use in Engine, transmission and differential. Since the RX-7\'s diffrential doesent need LS additives.
Sorry not sure what you don\'t beleive, if you ask specific questions I will get the answers from Prolong for you.
This should also answer some of the above questions,
A Rotary is different to a piston engine and you would never leave the oil in for 20,000 miles because of the slight petrol contamination you get, indeed if the oil gets to smelly it\'s best to change it,
Yes a lot of RX-7 guys change oil at 3,000 but Mazda recommends the RX-8 service intervals at 12,500 miles or 1 year in essentially the same engine, however the same as mentioned above Prolong is also able to withstand longer service limits.
My personal recomendation would be extend the milage interval if you wish just make sure the oil does not start to smell too much of petrol or if you see "mayonase", change it.
Don\'t forget that with this oil you get a full oil system warrenty that includes the apex seals (tips) if they wear and as far as I know no other oil on the market offers this.
I have even asked if the warrenty applies if the compression is low and the answer was "Yes" because whilst the oil will not mend low compression it will stop the compression getting and worse due to wear.
Hope this helps