Most of the long-term independent oil tests are done on Mobil. That'* why I chose it. I run mine 5000 and change it. I had UOA done on my first and second rounds with Mobil1 at 5k miles, and both came out cleaner than 3000 mile dino-juice UOA in my SSEi.

I've used Mobil 1 and have been happy with it. The previous owner of this car used the same stuff ever since the car got it'* first oil change. I haven't tried anything else though.

Thinking about this more.. I think the Mobil 1 is typically used more often due to easy of availabileity over say Amsoil and it being the first syn.

Mobil 1 sells for a cheaper price vs amsoil, that basically drives me to use mobil

I used to use Castrol Syntec before I bought the SSEi. I used Pensoil on the 94 SE and I've started using the Mobil1 with the SSEi. I can't really give an opinion on it yet other than "damn it cost alot more" .

Based on other opinions of people I've asked and read about on the boards here, I'd suggest the Mobil1.

The difference will show when you change it. It comes out the same consistency as it went in...

I run Castrol Synthetic in my Firehawk. As far as good vs. bad, I have no idea! I'm just maintaining what SLP put in it when new.

While on the topic of synthetic oil, what are peoples opinions about switching to syn. after running non-syn. for years?

The only downside is the added detergents could break down any sludge deposits that might be sealing gaskets. However in your case..all the gaskets are new. Go for it.

I switched at about 85k with no problems.

Most people will never notice the difference in oil in the time they own their cars. There'* no obvious benefit to synthetic over Dino convential oil, other than LONG term wear. It cannot be felt or seen, but has been proven in oil analysis over time.