Compression judged by starter strength
 

I have a thought that I would like to confirm.

I have a auto 04' rx8 that I bought under the impression was a well kept and maintained car. Which it was to a degree, but after some cooling system issues was wondering if it could have affected my compression. I know a compression test is the way to know, but can the time it takes to start your car tell you the general compression of your car.

Me for example, I have one of the older weaker starters, so if my car takes like 2 seconds to crank would that imply decent compression?

I also happen to use it as an everyday car, and always use premix and high octane although sometimes just run on ho, are their any other measures to try and save the apex seals?

I am a noob so I hope if I am incorrect about any of this information, I can be corrected.

Starter speed will affect engine RPM at start up and thus produce less than ideal compression test results. If you really want solid compression numbers the engine needs to be spinning at 250-300RPM. A good series II starter can make a low compression engine crank right up. We tested that theory on a buddies low compression engine when I purchased a new S2 (09'+) starter. If you are seeing 250RPM at start up and still having long cranking times then it is likely a low compression engine. But, not always, many things can cause cranking issues.

Engine: Troubleshooting

http://foxed.ca/rx7manual/2003mazdarx8/

So does this mean if I still have an S1 starter and it starts up great, then I most likely have good compression?
I understand there is a 5 second start rule, that if it takes longer than 5 seconds to crank then it most likely means bad compression.
So the quicker it starts would most likely means its okay, right?
and I probably have a pretty worn starter because everything was original, so could wd-40 work to give it some spark?