well spyder I went thru the same thing your doing now. I switched to synthetic at 100,000 miles, I still have my original motor 128,988 miles and even uped to a 14b on 18psi daily and NEVER EVER had engine problems sence mile 1 of my car. And yes I do appove of moble 1 full synth because I personally want to protect my older mile engine. Just make sure you change EVERY 3k or so. Actually im going on 5k miles without an oil change atm but I know my good ol mobile 1 is rdy. Ive heard all the bs on how changing will cause leaks etc etc etc. Im 5k miles into my oil and my oil is as CLEAN as I just put it in(well mostly). But before that ive went thru 10 oil changes EXACT on the 3k mile change and my car is treating me well. My spyder is a living testamony of a DSM that has ALWAYS been ABUSED and NEVER had a $1000+ fix ever. Most to date was when my 2nd gear chipped a tooth and thats because I went 120,000 miles before EVER changing the fluid.