I'm curious to know if anyone else has done this. Obviously there are numerous parameters that must be taken into account when selecting an oil change interval, generally based on UOA, but I believe oil pressure can provide a useful, qualitative assessment of oil shear. I use this technique in my RX-7, which shears oil much faser than a normal oil because of fuel dilution, among other factors. When the pressure begins to drop below 60 psi at 3,000 rpm (factory spec), that's a good indicator it's time to change it.

 

That seems like a horrible idea to me. You could have ice water in the system and get pressure - all pressure shows is pressure, it has nothing to do with the quality of the oil or its remaining life. What gave you this idea?

 

Can you tell me where you sourced this? I assume this spec for the 2.2?

 

[QUOTE=Saki GT,Mar 27 2009, 01:15 PM] That seems like a horrible idea to me.

 

that's for an RX-7, not an S2000...I'm not sure what the oil pressure spec for the S2000 is

 

You'll spend a lot of time recording data to get repeatable data for oil pressure vs temp vs RPM.

The 13B/12A is a totally different animal when it comes to oil consumption and dilution.
I know of a few FD owners that run 2 stroke premix and delete the oil injection, and run them like a 2 stroke.

I'd rather go with a UOA, which would be more accurate, as the oil pressure on a higher milage engine is going to be lower than a new one with tighter bearing tolerances.

Stock oil pressure runs anywhere from 15-25psi @ idle to 125psi @ WOT, with higher idle pressures when cold.

 

after reaching operating temps, I don't know why oil pressure would significantly change from one drive to another

yes, that's what I do, but injecting two stroke oil in the gas at 125:1 isn't going to impact oil pressure

UOA is the best way to determine OCI, no question, but this could be used as a useful analog, in my opinion

 

I used to do somewhat of the same on my LT1 camaro. Watch the gauge @ idle when warmed up. I always did oil change before 5K miles, but if I noticed the oil pressure gauge went lower, I'd change it with a fresh batch. Right after a change, the pressure would go back to its original position, so I knew it did do something - by the way, my LT1 was old and lots of unburnt fuel probably went past the rings.

The only problem was when the idle would change...

 

Ohh. and the S2K has no oil pressure gauge so its hard to do..unless you have one wired for turbo or something

 

Right, you have to install a sender and gauge, but it wouldn't be that tough. I'm a little surprised the S doesn't have one because it's very handy to tell when the oil is warmed up, it takes longer than the water temp, generally.