As usual, I run an oil analysis on a sample of my oil around every 5,000 miles.
Below are the results.
(Note that Sample #1 is Royal Purple, the rest are Amsoil's Signature Series)
This most recent sample I didn't run it as long because I wanted to send the sample in at 100,000 miles. There's also a longer time period between samples since I bought a second vehicle back in August (2007 Yamaha R6).
No major issues so far on the car. Nothing had to be repaired yet. Fuel dilution was a bit worse but I had my car idling a LOT this oil change, so not a concern. I replaced my spark plugs at 90,555 and it seemed to help the fuel dilution a bit.
Next oil change: 15,000 miles!!!
Now that Amsoil has released their Ea (15,000 limited warranty oil filters) for Toyota applications, I'm totally going to try it out and be the guinea pig for the Celica community. (Current sample is with a WIX filter, previous ones were using a MANN filter)
Previously they withdrew their original EaO 25,000 mile filters for Toyotas due to some cars filling the filters before 25,000 miles. After some research they modified them and are re-releasing them for 15,000 miles / 1 year. (Link for anyone interested
, the GT-S uses the Ea15K10)
I'm going to continue running samples at every 5,000 miles and posting them for anyone's interest. I take the sample from the dipstick with a small hose and fluid pump.
If I can keep my fuel dilution to a minimum, I should be able to make it until 15,000 miles. (Seems the 2ZZ-GE is susceptible to fuel dilution in extended oil changes though)
My average MPG is about 31 MPG. If I drive economically I can achieve 35 MPG (most recently). Typically though I drive fairly aggressively.