"it had mobil one synthetic on it before... my recent oil change (which was castrol gtx)... can i go back to mobil one synthetic? and is there different performance? or different like on my engine by using one or the other?"
You can put Mobil 1 synthetic in your car this week, regular Castrol in it next week, Penzoil (sp?) in it two days after that, and then change it back to Mobil 1, and your engine wont care. In fact, when doing engine flushes (Im not talking about with a machine, just add in flushes like CD2) you have to use dino oil, unless you like throwing away expensive synthetic oil. I ran Mobil 1 Synthetic in my Cougar even though it ran dino oil for 14k miles. I put another 14k miles on it with synthetic and it ran just fine. Ended up going back to dino oil for a few changes when I did an engine flush, and went right back to synthetic without missing a beat. Is there different performance? Perhaps, depending on your definition of performance. Will your car gain 2/10th's in the quarter? Probably not. Will your engine be quieter with synthetic? It very well could be. Will it run smoother? It just might. If it was my car, Id go back to Mobil 1. Its a great oil, and IMHO your engine will last longer with it.
"they said synthetic is useless after 50,000"
People like those guys are why no one touches my car except me, and maybe my dad and brother. They dont know what they are talking about. If your car was running fine for 50,000 miles on organic oil, and you decided to run synthetics for the rest of your engine's life, guess what? Your engine would run just fine from here on out. If fact, it might just run a little better, smoother, quieter, and last longer.
After this first oil change in my Prelude, you can bet Ill be putting Mobil 1 in it from here on out.
