I remember reading on one of the many synthetic oil threads where someone said you shouldn't START using synthetic oil if you have too many miles on your RX8. I have almost 30,000 miles after 1 year of ownership. I would like to hear some viewpoints on this issue.

I recently decided to try doing my own oil changes and thought I might like to try Royal Purple or Red Line or whatever.

 

It should be okay to switch over to synthetic (if you want to) since after the mileage you've covered, the apex seals would be well worn in and "lubricated".

 

This is what alnielsen said in the Red Line Synthetic Motor Oil thread:

"I work at BP/Amoco. And while I am not a Chemical Engineener, I take care of the computers of a few. Including the ones that specialize in lubricating oil. I brought up the question about synthetic oil in the combustion chamber and the answer I recieve is they burn clean and leave no residue and wouldn't harm the apex seals. The only thing that seemed a problem was switching from mineral base oil to synthetic. My car has 4000 mi on it and he said that wasn't too bad, but switching at 20k wouldn't be recomended."

 

Synthetic oil has a higher detergency level than conventional oils.
That is why a synthetic engine is a clean engine. (in general)
A big issue with switching to synthetic oil in a 'used' motor is how clean it is.
If your motor is well taken care of, I believe you are ok.
If your motor is 'dirty', the synthetic oil will mobilize this crap and problems are possible.
Also, never switch to synthetic if there are leaks. They will get worse.

I have run synthetic in all my cars for the past 13 years.
I switched to synthetic at 70k miles in 1 car I purchased with no issues.
It was well maintained prior to my purchase.

Clean engine.. no leaks.. I think you are ok and much better off changing over to synthetic.

Note this is my opinion based on my experience.

-B

 

Awesome. Thanks for the information, TooBig.